e Aviation Theory Course for
rline Transport Pilot Compiled by Li Weidong Hao Jingsong He Qiuzhao
THE AVIATION THEORY COURSE FOR
Airline Transport Pilot Compiled by Li Weidong Hao Jingsong He Qiuzhao
Southwest Jiaotong University Press Chengdu, China
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CONTENTS Chapter! Regulations······ ·· · · ·• ·••••••· •· •••••••• •·•••••••••• •••· ••· ••••••••••••••••••••••••• ••· •••• •· • 1 Section A Applicable Regulations •••••• ••• ••••·• ••• ••• •·• ·• · ••• · •• ••• ••• ••• ••••••••• ••• ••• ••• ••• ••• I Section B The ATP Ce.rtificate· •• · · · •••• •• •· · ••• ••• · · · · •• · •• ••• ••• · •• •• •••• ••• ••• • •• •· •• •• · •• · ········ I 2 Section C Flight Engineer Requirements SectionD Flight Attendants···························································· •·•··· ··· ··· ··· 3 Section E Experience and Training Requirements ••• · · · .. •••• •• ••••••• •••... · •• •••·•• ••• ••• •·• ... 4 SectionF Flight Crew Duty' Time Limits •• •· •• ••• •· •••• ••· · · · •· •••••·• •·• ••• ••• · · •••• ••· ••• ••· ·•• 6 SectionG Dispatching and Flight Release······················································ ···19 Section H Fuel Requirements····································································· ···20 Section I Carriage of Passengers and Cargo···································· ·••· ·••·••••· · · •••21 • •••• ••••••••••••• I l l ••••••••••••••••••••••••••••••••••••
Section J
Emergency Equipment and Operations ... •••••· · •••••••.. •••.. •••· ••.. •••• •••••....... 23
Chapter 2 Equipment, Navigation and Facilities · ·· ··· ·•• · •· · •• ••• ••• · ·· ••• · ·• · ·· · ·• ••• ·•• ••• •• · ••• 27 Section A Inoperative Eq_uipment ••• •••••• ••• ••• ••• ••• ••• ••• ·•• ••• ••• ·•• ••• ••• ••• ••• ••• ••• ••• ·•• ·•• 27 Section B Pitot-static lnstrllments············ •••·•• ··•·•· ·••·•• •••••• •••••• ••• ••• ••••••••• ••••••·•• 27 Section C Safety of Flight Equipment ••· ••• •••· •• ••• ••• · •• ••• ••• ••• ••· ••• · •· · ·• · ·• ••• · •• ••• ••• ••• 30 SectionD Communications ••• ··• •• •••• · •• ·•· ••• ••• •• ••·• ••• ••• ••• ••• · •• ••• ••• · ••• •· ••• ••• · •· ••• ••• 32 Section E Navigation Equipment ••·••••••••••••••••••••••••••• ·•••••••••••••••••••• ···············32 Section F Horizontal Situ.ation Indicator ·•• ••• ••• •· · •· · · · · ·•· ••• ••• ••• ••••• •••• ••• ••• ••• ••• •·• ••· 34 Section G Radio Magnetic Indicator (R.MI) ••••••••• ••• ••••••••• ••••••••••••••••••••• ••• ••••••••• 37 Section H Long Range Navigation Systems ••• ••• ••• ••• ••• ••· ••• ••• ••• ••• ••• ••• ••• ••• •·• ••• ••• •·• 38 Section I Approach Systems··· ·····································································39 Section J Global Positioning System ••• •••••••••••••••••••••..••••.••••• ••••..••..•••••••••••••• 43 Section K Airport Lighting an.d Marking ••• •••••• •·••· •••· ••••••· •••••••••••••· •••••••·• ·••••••••44 Section L Approach Lighting ........................................................................ 47 Chapter3 Aerodynamics •••· •• ••• ••• ••• ••• ••• ••• ••• ••• · ••••• ••• •· · • •• ••• ••• •••• •• ••• ••• ••• ••· ••· •• · · •• 49 Section A Lift and Drag .••.••••••••••••••••••.•••••••.•••••.••.•.••••••••••••••••••.••••••••...••• 49 Section B Stability···················································································· 53 Section C Flight Controls · ·• ··· ··· ··• · ·• ·•• ••· •• · ••• · •• ••• ·•• ••• ••• ••• ••• •••·•• · ·• ••• · •• ••• ••• · ·····54 SectionD High-lift Devices ••• ••• ••• ••· •••••• ••• ·•• ••• ••• •••••• ••• · •• · •· •·• •·• · •· ••• ·•• •· •••• ••• ••• 56 ..•..•.•••••.••••.••••••.••.•••••.••.••..•....••......•••••••.•••••••.••.••••••••.••••• 57 Section E •••••••••.••.••••••.••.•.•••..••••••••••••••••••.•••••••••••..•.•......•..••••••••••••• 58 Section F
SectionG High Speed Fligh.t· •• ••• ••• ••• ••• ••• ••• · •• •• · ••• ••• ••· ••• ••• ••• •· •· •• · ·• · · · · · · ••• ••• ······59
Chapter 4
Perfonnance · · · · · · · · · ·· · · · · · · · ·· · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· · · · · · · · · · · · ·· · · · · .. · · · 6 I
Section A Section B Section C Section D Section E
Engine performance ... ·· · · · · · · · · · · · · · · ·· ·· · · · · · · · · · · · · · · · · · · · · · · .. ·· · · · · · · · · ·· · ·· · ·· · · · · Take-off Perforn1ance ·· · · · · · · · · ·· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·· · · · · · · · · · · · · · · ·· · ·· · · · Climb Performance · · · · · · .. · · ·· · · · · · ·· · · · · · · · · · · · · · · · · · · · · · · · · .. · · · · · · · · · · · · · · · ·· · ··· ·· · Cruise Perforn1ance · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · .. · · ·· · · · · · · ·· · ·· · · · · · · · Landing Performance ............ ......................................................
61 64 78 90 91
Section F
Miscellaneous Perforn1ance ......... .......... .. ............................ ........ 103
Section G Engine-out Procedures · .. · .. · · · .. · · · · · · .... · · .... · · · · · · · · · ·· · · · .............. ·· · · · · · · 108 Section H Flight Planning Graphs and Tables · ·· · · · · · · .. · .. · · · · · .. · .. · ............ · · · · · · ·· · · · Ill Section I Typical Flight Logs ............ ·· .... · ........... ·.... · ...... · .... · .. ·.... ·.......... 115 Chapter 5 Weight and Balance ...................................... · .......................... · ... 132 Section A Introduction .................. ......................................................... 132 Section B Weight and Balance Principle ................................. ..................... 133 Section C Center of Gravity Computation and Stabilizer Trim Setting"· .... ·········· ... · 137 Section D Changing Loading Condition ......................................................... 148 Section E Floor Loading Limits ....... .. ............................................. ............ 150 Chapter6 FlightOperations ...................................................... .................. 151 Section A Section B Section C Section D Section E
Airspaces .. · .. · .............. · .... · · · · .... · .... · · .. · .. · .. ...... · .. ........ · .. · · .... · .. · NOTAMs (Notices To Airmen) ....................... · .................. · .... ·...... Items on the Flight Plan .................................................... ........... Selecting an Alternate Airport ......... .................. ........................... ATC Clearances.................................... ....................................
151 152 154 156 158
Section F Take-off Procedures ........ · .. · .. · ........ · ..................... .... · .... .. · .. · .. · .. · 159 Section G Instrument Approaches ............................................................... 161 Section H Landing..................................... ............................................ 168 Section I Section J Section K Section L
Communications ..................................................................... Speed Adjustments . .. ............................................................... Holding ...... · .. · .... · · .. · .... · .. · .... · ...... · ........ · .. · ........ · ........ · · .... · ·.... · Charts for Instrument Flight .... · · .......... · .................... ·.... .............. ·
168 169 170 173
Chapter 7 Emergency, Physiology and Crew Resource Management...... ·................. 196 Section A Flight Emergency and Hazards...................................................... 196 Section B Flight Physiology · .... · .. · .. · · .. · .......... · ........ · ...... · .... · · .... · · ........ ··· .. · 209 Section C Situation Awareness, Communication, Leadership and Decision Making .. · .. · 224 Chapter 8 Aviation Meteorology .. · .... · .................. · ...... · .. · ................... · ...... ...
236
Section A Basic Theories ...... · · ................... · ........ · .............. ...... · .... · .. · ·.... · 236 Section B Hazard Weather. .. · .... · .. · ... ·.................... · .......... ·· ........ · ........ · .... · 256 Section C Aviation Weather Services .................... · .. · ............ ·........ ·........ ... 275 Appendix ..................... ............ .................................... ...... .....................
315
References .. · · .. .. · .. · ·· · · .. · .... · .. · .. · .............. · ...... · · · .. · .. · .. · · .. · · · .. · .. · ·.... · .............. · 319 2
REFERENCES 1 fiii~•.~ Et!.-TW:-l\.d: wm30!*~wJt&tl. 2002 2 .:£1jl!l.~~.d: wm30i*~iliJt&l±, 2001
3 4 5 6 7 8 9 10 11 12
13 14 15 16 17 18 19
~Ni;.~filjmNi:RJ . tJ:I IE ~ffl~ HNi:1Jl1lt~tJ?-: ~IN ~Aiitlill&tl
Airbus 320 FCOM. Airbus Industry/Flight Safety, 1998 Airline Transportation Pilot test Prep 2004. ASA, Inc, 2003 Instrument Flying Handbook. ASA, Inc, 1980 Boeing 737-300 Operating Manual Boeing Company, 1996 China Civil Aviation Regulations. Dale R Cundy, Rick S Brown. Introduction to Avionics. The Prentice--Hall, 1997 EHJ Pallett Aircraft Instruments & Integrated System. Longman Group UK Limited, 1992 FAA. Airman's Information ManuaL 1994 Harry W Orlady, Linda M Orlady. Human Factors in Multi-Crew Flight Operations. Ashgate Publishing Ltd, 1999 Ian B Suren. Aeroplane Perfonnance, Planning & Loading for the Transport Pilot. Aviation Theory Centre Pty Ltd, 1998 J Powell. Aircraft Radio Systems. Pitman, 1986 Instrument/Commercial Manual. Jeppesen Sanderson. Inc, 1994 Private pilot manual. Jeppesen Sanderson. Inc, 1988 K D Campbell, M Bagshaw. Human Perfonnance and Limitations in Aviation. Second Edition. Blackwell Science Ltd, 1999 Martin B Bshelby. Aircraft Performance Theory and Practice. American Institute of Aeronautics and Astronautics, Inc, 2000 The Pilot's Reference to ATC Procedures and Phraseology. California: Reavco Publishing, 1992
319
PREFACE Congratulations on you to continue your pilot training and welcome to The Aviation Theory Course for Airline Transport Pilot. This book is designed as a textbook and a reference for the Civil Aviation Administration of China (CAAC) knowledge Test about Airline Transport Pilot License (ATPL). The important points are summarized in the course; it is based on the study/review concept of learning. So, it has been helping pilots prepare for the test with great success.
MAIN CONTENT All of the knowledge for the ATP is included here, and has been arranged into 8 chapters based on each subject matter. They are Chapter 1, Regulations; Chapter 2, Equipment, Navigation and Facilities; Chapter 3, Aerodynamics; Chapter 4, Performance; Chapter 5, Weight and Balance; Chapter 6, Flight Operations; Chapter 7, Flight Emergency and Hazards, Flight Physiology and Crew Resource Management; and Chapter 8, Meteorology and Weather Services. Each chapter includes main knowledge about the subject
USE OF THE COURSE Airman knowledge about ATP requires applicants to understand it. All of the knowledge is faced with ATPL examination. It is designed that user will have two sets of learning, understanding and reviewing the basic knowledge appropriately. The intent is that all applicants keep on eye on basic concepts, procedures and methods made from the whole chapters. These are important to ainnan for transport aircraft fly. Some of the information may seem basic. There are two reasons for this: Many prospective private and commercial pilots and instrument rating knowledge are learned before, so some review
is helpful; also, the airline transport knowledge is based on them but deeper than them. However, we are not going to cover all of the information, because the pilot's basic knowledge for initial pilot would be presumed up to know. If it has been a long time since you reviewed the knowledge requirements of the initial information, it might benefit you to review the Aeronautical Theory Course for Pilot (Chinese Edition, pressed by Southwest Jiaotong University Press, March, 2004).
This course is the key element in airman knowledge materials for ATPL. Although it can be studied alone, we still suggest the user to join the teaching training. You may get many more understanding from your instructors. You may learn from other materials such as CAAC aviation regulations, Flight courses and other teaching materials provided by ATP training organizations. Then, you will be excellent to pass the theory test for ATPL.
This introduction has implied a heavy emphasis on knowledge exams, but that is not our style as an instructor. What you need to know for the knowledge test represents less than the course text -
the rest is solid information you must study from the Chinese Civil Aviation
Regulations (CCAR, i.e. CCAR 61, CCAR 91 , CCAR 121 and so on) and other reference books. You will also note an emphasis on computer-based training system (CBT). Most pilots are to some extent technically oriented, and it is estimated that well over all pilots use airline computers for flight planning, acquiring weather information, maintaining their logbooks, etc. Accordingly, we have included access information wherever it is appropriate. As CBT surfers know. if you can find one-by-one question showed on the computer, then you choice only one correct answer for the question with clicking the mouse button. And then you will get hold of all of the ATP knowledge gradually. Finally, we shall give thanks to the writers of this course; they are Ma Zhigang, L uo Jun, Hao Jingsong, Wei Lin, Liu Duhui, Xiang Xiaojun, Yang Junli, Fang Xuedong, Jiang Bo, He Qiuzhao,
Li Weidong, Mou Haiying, Huang Yifang, Zou Bo and Chen Huizhi. This course is compiled by Li Weidong, Hao Jingsong and He Qiuzhao. All of the writers are the experts about a\iation theory and come from the Civil Aviation Flight University of China. We believe it is a great contribution for CAAC. We wish this book will provide a good reference to you. We are confident that \\ith proper use of this book, you will score very well on any of the Airline Transport Pilot tests.
CHAPTER 1 REGULATIONS SECTION A
APPLICABLE REGULATIONS
"CCAR" is used as the acronym for "China Civil Aviation Regulations". Those regulations or rules are very important for operations of aircraft, and other aspects in that field. The regulations change frequently, and answer all questions in compliance with the most current regulations. Two different China Civil Aviation Regulations can apply to operations of aircraft covered by this chapter: CCAR 91, 121. CCAR 91 encompasses the general operations and flight rules for all aircraft operating within the Peoples' Republic of China. Often the rules of CCAR 121 supplement or even supersede CCAR 91. When an aircraft is not operated for compensation, only the CCAR 91 rules apply. For the test, assume CCAR 121 rules apply unless the question specifically states otherwise. CCAR 121 applies to air carriers (airlines) engaged in China or overseas air transportation. Carriers which operate under CCAR 121 are engaged in common carriage. This means that they offer their services to the public and receive compensation for those services. CCAR 121 operators are subdivided into three categories. Carriers authorized to conduct scheduled operations within China are domestic air carriers. Flag carriers conduct scheduled operations inside and outside China A supplemental carrier conducts its operations anywhere that its operations specifications permit but only on a non-scheduled basis. There is a fourth category, commercial operators of large aircraft, but they must comply with the rules covering supplemental carrier and the distinction is unimportant to this discussion. Other parts of the regulations apply as well. CCAR 61 governs certifications of pilots and fl ight instructors. CCAR 67 covers the issuing and standards for medical certificates. CCAR 65 prescribes the requirements for issuing certificates and associated ratings and the general operating rules for the holders of those certificates and ratings.
SECTION 8
THE ATP CERTIFICATE
The pilot-in-command of an air carrier flight must hold an Airline Transport Pilot (ATP) certificate with the appropriate type rating. The co-pilot on an air carrier flight that requires only
two pilots need only hold a Commercial Pilot certificate (with an Instrument rating) with the appropriate category and cl$5 ratings. A person must hold a type rating to act as pilot-in-command of a large aircraft (over 5 700 kg gross take-off weight), or of a mrbojet-powered airplane. Any type rating(s) on the pilot certificate of an applicant who successfully complete an ATP checkride will be included on the ATP Certificate with the privileges and limitations of the ATP Certificate, provided the applicant passes the checkrjde in the same category and class of aircraft for which the applicant holds the type rating(s). However, if a type rating for that category and class of aircraft on the superseded pilot certificate is limited to VFR, that limitation will be carried forward to the person's ATP Certificate level. An airline transport pilot may instruct other pilots in air transportation service in aircraft of the category, class and type for which he/she is rated. However, the ATP may not instruct for more than
8 hours in one day. A person who has lost an Airman's Certificate may obtain a temporary certificate from the CAAC. The temporary certificate is valid no more than 120 days. A crewmember is a person assigned to duty in the aircraft during flight This includes pilots, flight engineers, navigators, flight attendants or anyone else assigned to duty in the airplane. A flight crewmember is a pilot, flight engineer or flight navigator assigned to duty in the aircraft during flight No person may serve as a pilot on an air carrier after that person has reached his/her 60th birthday. Note that this rule applies to any pilot position in the aircraft, but it does not apply to other flight crew positions such as flight engineer or navigator. To exercise ATP privileges (such as pilot-in-command of an air carrier flight) a pilot must hold a First-Class Medical Certificate issued within the preceding 6 or 12 calendar months. To exercise commercial pilot privileges (e.g., co-pilot on a two-pilot air carrier flight) a pilot must hold either a First- or Second-Class Medical Certificate issued within the preceding 12 or 24 calendar months. The applicant is not required to hold a medical certificate when taking a test or check for a certificate, rating, or authorization conducted in a flight simulator or flight trainillg device.
SECTION C
FLIGHT ENGINEER REQUIREMENTS
Many air carrier aircraft have a flight engineer as a required flight crewmember. The aircraft "type certificate" states whether or not a flight engineer is required. On each flight requiring a flight engineer at least one flight crewmember, other than the flight engineer, must be qualified to provide emergency performance of the flight engineer's functions for the safe completion of the flight if the flight engineer becomes ill or is otherwise incapacitated. A pilot need not hold a Flight Engineer's Certificate to perform the flight engineer's functions in such a situation.
2
SECTION D
FLIGHT ATTENDANTS
One or more flight attendants are required on each passenger-carrying airplane that has more than 19 passenger seats. The number of flight attendants is determined by the number of installed passenger seats - not by the actual number of passengers on board. Each certificate holder shall provide at least the minimum number of flight attendants on each passenger-carrying airplane. For airplanes having a seating capacity of more than 20 but less than 50 passengers: at least one flight attendant. For airplanes having a seating capacity of more than 51 but less than 100 passengers: at least two flight attendants. For airplanes having a seating capacity of more than 100 passengers: at least two flight attendants plus one additional flight attendant for each unit (or part of a unit) of 50 passenger seats above a seating capacity of 100 passengers. If, in conducting the emergency evacuation demonstration required under CCAR 121, the certificate holder used more flight attendants than is required under the paragraph above of this section for the maximum seating capacity of the airplane, he may not, thereafter, take off that airplane in its maximum seating capacity configuration with fewer flight attendants than the number used during the emergency evacuation demonstration; or in any reduced seating capacity configuration with fewer flight attendants than the number required by the paragraph above of this section for that seating capacity plus the number of flight attendants used during the emergency evacuation demonstration that were in excess of those required under the paragraph above ofthis section. The number of flight attendants approved under the paragraphs above of this section is set forth in the certificate holder's operations specifications. During take-off and landing, flight attendants required by this section shall be located as near as practicable to required floor level exists and shall be uniformly distributed throughout the airplane in order to provide the most effective egress of passengers in event of an emergency evacuation. During taxi, flight attendants required by this section must remain at their duty stations with safety belts and shoulder harnesses fastened except to perform duties related to the safety of the airplane and its occupants. At stops where passengers remain on board, and on the airplane for which a flight attendant is not required by CCAR 121, the certificate holder must ensure that a person who is qualified in the emergency evacuation procedures for the airplane as required in CCAR 121, and who is identified to the passengers, remains on board the airplane, or nearby the airplane, in a position to adequately monitor passenger safety; and the airplane engines are shut down; and at least one floor level exit remains open to provide for the deplaning of passengers. On each airplane for which flight attendants are required by CCAR 121, but the number of flight attendants remaining aboard is fewer than required by CCAR 121, the certificate holder shall ensure that the airplane engines are shut down, and at least one floor level exit remains open to provide for the deplaning of passengers; and the number of flight attendants on board is at least half the number required by CCAR 121, rounded down to the next lower number in the case of fractions, but never fewer than one. The certificate holder may substitute for the required flight attendants
3
other persons qualified in the emergency evacuation proced:!:res fir th:!:t .,.;- ~t'a.l.~ as required in CCAR 121, if these persons are identified to the passengers If~ roe :.~ a:tendant or other qualified person is on board during a stop, that flight anendant or 0
SECTION E EXPERIENCE AND TRAINING REQUIREMENTS For these definitions of training, aircraft are divided into two "groups". Group I aircraft are propeller driven. Turbojet aircraft are Group ll. Initial training is the training required for crewmembers and dispatchers who have not qualified and served in the same capacity (i.e., flight engineer, co-pilot, pilot-in-command) on another aircraft of the same group. Transition training is the training required for crewmembers or dispatchers who have qualified and served in the same capacity on another aircraft of the same group. Upgrade training is the training required for crewmembers who have qualified and served as second-in-command or flight engineer on a particular airplane type (e.g., Boeing 737) before they can serve as pilot-in-command or second-in-command, respectively, on that airplane. Differences training is the training required for crewmembers or dispatchers who have qualified and served on a particular type of airplane before they can serve in the same capacity on a variation of that airplane. For example, a crewmember who is qualified on a Boeing 737-300 would need differences training to serve on a Boeing 737-400. For a person to serve as pilot-in-command he/she must have had a proficiency check within the preceding 12 calendar months. In addition, within the preceding 6 calendar months the pilot-in-command must have either passed a proficiency check or completed an approved simulator training course. No certificate holder may use any person nor may any person serve as pilot-in-command of an airplane unless, within the preceding 12 calendar months that person has passed a line check in which he/she satisfactorily performs the duties and responsibilities of a pilot-in-command in one ofthe types of airplanes to be flown. Pilots other than the PIC (pilot-in-command) must have either passed a proficiency check or completed "line oriented" simulator training within the last 24 calendar months. In addition, the co-pilot must have had a proficiency check or any other kind of simulator training within the last 12 calendar months. Whenever a crewmember or aircraft dispatcher who is required to take recurrent trainings, a flight check, or a competency check, takes the check or completes the training in the calendar month before or after the month in which that training or check is required, he/she is considered to have taken or completed it in the calendar month in which it was required. When a pilot has not made 3 take-offs and landings within the preceding 90 days, the pilot 4
must make at least 3 take-offs and landings in the type of airplane in which that person is to setve or
in an advanced simulator. These take-offs and landings must include: A. At least 1 take-off with a simulated failure of the most critical powerplant; B. At least 1 landing from an ILS (Instrument Landing System) approach to the lowest ILS minimum authorized for the certificate holder; and C. At least 1 landing to a full stop. No pilot may act as pilot-in-command under IFR (Instrument Flight Rule) unless he/she has, within the preceding 6 calendar months in the aircraft category for the instrument privileges sought, logged at least 6 instrument approaches, performed holding procedures, and intercepted and tracked courses through the use of navigation systems, or passed an instrument competency check in the category of aircraft involved. A pilot may log as instrument flight time only that time during which he/she operates the aircraft solely by reference to the instruments, under actual or simulated instrument flight conditions. If the pilot-in-command has not setved 100 hours as pilot-in-command in operations under CCAR 121 in the type of airplane he/she is operating, the MDA (minimum descent altitude) or DH (decision height) and visibility landing minimums in the certificate holder's operations specifications for regular, provisional, or refueling airports are increased by 100 feet and 800 m [or the RVR (runway visual range) equivalent]. If the pilot-in-command has not setved 100 hours as PIC under CCAR 121 operations in the airplane type, the MDA or DH visibility minimums are increased by 30 m and 800 m above the published minimums. If a flight goes to an alternate airport, the minimums do not have to be raised by 30- 800 m, but they can not be less than 100-1 600 m. In addition, Category II (CAT II) minimums and the sliding scale do not apply. If a pilot has at least 100 hours PIC in another aircraft under CCAR 121 operations, he/she may reduce the current restriction by 1 hour for each landing, up to 50 hours maximum. To be eligible for Category II authorization, a pilot must have made at least 6 ILS approaches since the beginning of the 6th month before the test These approaches must be under actual or simulated instrument flight conditions down to the minimum landing altitude for the ILS approach in the type aircraft in which the flight test is to be conducted. However, the approaches need not be conducted down to the decision heights authorized for Category II operations. At least 3 of these approaches must have been conducted manually, without the use of an approach coupler. Upon original issue, a Category II authorization contains a limitation for Category II operations of 1 600 feet RVR and a 150-foot decision height. This limitation is removed when the holder shows that since the beginning of the 6th preceding month he/she has made 3 Category II ILS approaches to a landing under actual or simulated instrument conditions with a 150-foot decision height No domestic or flag air carrier may use any person as an aircraft dispatcher unless, within the preceding 12 calendar months, he/she has satisfactorily completed operating familiarization consisting of at least 5 hours obsetving operations from the flight deck under CCAR 121 in one of the types of airplanes in each group he/she is to dispatch.
5
SECTION F
FLIGHT CREW DUTY TIME LIMITS
The time limits in this section count all commercial flying done by the crewmember in any flight crew position, not just the time flown with the air carrier. Besides the limits on flight time, there are required periods of rest based on the amount of flying done within a 24-hour period. There is also a requirement that a flight crewmember be given at least 36 consecutive hours of rest in any 7 consecutive days periods. A person cannot be assigned to any ground or flight duties during required rest periods. The term "deadhead" is used to describe the transportation of crewmembers by the air carrier to or from their flight assignments when that transportation is not local in character. Time spent in deadhead air transportation cannot be considered part of a required rest period. No pilot of a supplemental carrier may be on flight deck duty for more than 8 hours in any 24 consecutive hours. If three pilots are assigned to a flight, the crew can be aloft no more than 16 hours in any 24 consecutive hours.
PILOTS' DUTY PERIOD LIMITATIONS AND REST REQUIREMENTS Two Pilots Crews A crewmember's total duty period should not exceed 14 hours, and the flight time in the duty period should not exceed 8 hours. The flight time may be extended to 9 hours if there are no more than 2 segments in the flight After the duty period the crewmember must be given a scheduled rest period of at least 10 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case of any delays happening in the operation, the rest period may be reduced to 9 hours, if the actual duty period doesn't exceed the 14 hours' limitation. ln case of any delays happening in the operation, the duty period may be extended to 16 hours at most, but the rest period there after must not be reduced.
Three Pilots Crews, Including a Second- in-commander Pilot A crewmember's total duty period should not exceed 16 hours, and the flight time in the duty
--
period should not exceed 10 hours. The flight time may be extended to 9 hburs if it is a nonstop /
flight. After the duty period the crewmember must be given a scheduled rest period of at least 14 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case of any delays happening in the operation, the rest period may be reduced to 12 hours, if the actual duty period doesn't exceed the 16 hours' limitation. In case of any delays happening in the operation, the duty period may be extended to 18 hours at most, but the rest period there after must not be reduced.
Three Pilots Crews, Including a Second-in-commander Pilot, and an Approved Area of Sleep for Crewmembers During the Flight A crewmember's total duty period should not exceed 18 hours, and the flight time in the duty
6
period should not exceed 14 hours, provided each crewrnember could have chances to take a rest in the approved area of sleep during the whole flight After the duty period the crewmember must be given a scheduled rest period of at least 18 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case of any delays happening in the operation, the rest period may be reduced to 16 hours, if the actual duty period doesn't exceed the 18 hours' limitation. In case of any delays happening in the operation, the duty period may be extended to 20 hours at most, but the rest period there after must not be reduced.
Four Pilots Crews, Including a Second-in-commander Pilot, and an Approved Area of Sleep for Crewmembers During the Flight A crewmember's total duty period should not exceed 20 hours, and the flight time in the duty period should not exceed 17 hours, provided each crewmember could have chances to take a rest in the approved area of sleep during the whole flight. After the duty period the crewmember must be given a scheduled rest period of at least 22 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case of any delays happening in the operation, the rest period may be reduced to 20 hours, if the actual duty period doesn't exceed the 20 hours' limitation. In case of any delays happening in the operation, the duty period may be extended to 22 hours at most, but the rest period there after must not be reduced.
DUTY PERIOD LIMITATIONS AND REST REQUIREMENTS: NAVIGATORS, FLIGHT ENGINEERS AND BATMEN Duty Period Limitations and Requirements for a Crew with One Navigator, One Flight Engineer, or One Batman A crewmember's total duty period should not exceed 14 hours, and the flight time in the duty period should not exceed 9 hours. After the duty p'!riod the crewmember must be given a scheduled rest period of at least 10 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case any delays occur during the operation, the rest period may be reduced to 9 hours, if the actual duty period doesn't exceed the 14 hours' limitation; the duty period may be extended to 16 hours at most, but the 10 hours' rest period there after must not be reduced. A certificate holder may assign a navigator, a flight engineer, or batman to a scheduled duty period of more than 14 hours, but no more than 16 hours. The fljght time during the duty period should not exceed 12 hours. After the duty period the crewmember must be given a scheduled rest period of at least 14 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. In case any delays occur during the operation, the rest period may be reduced to 12 hours, if the actual duty period
7
doesn't exceed the 16 hours' limitation; the duty period may be e::-..'tended to 18 hours at most, but the 14 hours' rest period there after must not be reduced.
Duty Period Limitations and Requirements for a Crew with Two Navigators, Two Flight Engineers, or Two Batmen A certificate holder may assign navigators, flight engineers, or batmen to a scheduled duty period of more than 16 hours, but no more than 18 hours. The flight time during the duty period should be no more than 14 hours, provided each crewmember could have chances to take a rest in the approved area of sleep during the whole flight. After the duty period the crewmember must be given a scheduled rest period of at least 18 consecutive hours. This rest period must occur between the completion ofthe scheduled duty period and the commencement of the subsequent duty period. In case any delays occur during the operation, the rest period may be reduced to 16 hours, if the actual duty period doesn't exceed the 18 hours' limitation; the duty period may be extended to 20 hours at most, but the 18 hours' rest period there after must not be reduced. A certificate holder may also assign navigators, flight engineers, or batmen to a scheduled duty period of more than 18 hours, but no more than 20 hours. The flight time during the duty period should be no more than 17 hours, provided each crewmember could have chances to take a rest in the approved area of sleep during the whole flight. After the duty period the crewmember must be given a scheduled rest period of at least 22 consecutive hours. This rest period must occur between the completion ofthe scheduled duty period and the commencement of the subsequent duty period. In case any delays occur during the operation, the rest period may be reduced to 20 hours, if the actual duty period doesn't exceed the 20 hours' limitation; the duty period may be extended to 22 hours at most, but the rest period there after must not be reduced.
FLIGHT TIME LIMITATIONS AND REST REQUIREMENTS: FLIGHT CREWMEMBERS No certificate holder conducting operations may schedule any flight crewmember and no flight crewmember may accept an assignment for flight time in scheduled air transportation or in other commercial flying if that crewmember's total flight time in all commercial flying will exceed 1 000 hours in any calendar year, or 90 hours in any calendar month, or 35 hours in any 7 consecutive calendar days (this period of time may be extended to 40 hours, provided each crewmember could have a chance to take a rest in an approved area of sleep during each period of flight).
ADDITIONAL DUTY PERIOD AND FLIGHT TIME LIMITATIONS: FLIGHT CREWMEMBERS A flight crewmember is not considered to be scheduled for duty time in excess of duty time limitations if the flights to which he is assigned are scheduled and normally terminate within the limitations, but due to circumstances beyond the control of the certificate holder (such as adverse 8
weather conditions), are not at the time of departure expected to reach their destination within the scheduled time. In this case, the duty period and flight time limitations should also be consistent with those stated in CCAR 121, and the excess part of duty time should not in any circumstances exceed 2 hours. A flight crewmember is not considered to be scheduled for flight time in excess of flight time limitations if the flights to which he is assigned are scheduled and normally terminate within the limitations, but due to circumstances beyond the control of the certificate holder (such as adverse weather conditions), are not at the time of departure expected to reach their destination within the scheduled time. If a flight crewmember is assigned to serve for more than one certificate holder, or is assigned to serve in more than one type of flight crew, the total duty time and flight time limitations should be consistent with those stated in CCAR 121. Time spent before departure due to delay is considered part of the duty time.
ADDITIONAL REST REQUIREMENTS: FLIGHT CREWMEMBER No certificate holder may assign a flight crewmember to perform any duty with the certificate holder during any required rest period. The rest period stated in this section may be included in other rest periods. Only when a delay occurs in an operation, may a crewmember's rest period be reduced according to those stated in CCAR 121. The reducing must not be assigned ahead of time. Each certificate holder shall relieve each flight crewmember engaged in scheduled air transportation from all further duty for at least 36 consecutive hours during any 7 consecutive days. When a certificate holder assigned other duty for a flight crewmember, the time spent in the duty may or may not be considered as part of the flight duty time. When it is not considered as part of the flight duty time, the flight crewmember must be assigned a rest period of at least 8 consecutive hours before commencement of the subsequent duty period. If there is a jetlag of 6 hours or more between the time zone where the flight operation terminates and the time zone where the flight crewmember's home station locates, the certificate holder should assigned a rest period of at least 48 consecutive hours for the flight crewmember after he or she is back to the borne station. This rest period must occur before the commencement of the subsequent duty period. The home station stated in this section refers to the place where flight crewmembers are stationed, and flight crewmembers' duty times are assigned there. Time spent in transportation, not local in character, that a certificate holder requires of a flight crewmember and provides to transport the flight crewmember to an airport at which that flight crewmember is to serve on a flight as a crewmember, or from an airport at which the flight crewmember was relieved from duty to return to the flight attendant's home station, is not considered part of a rest period. 9
FL I GHT ATTENDANT DUTY PER I OD LIMITAT IONS AND REST REQU I REMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Calendar day means the period of elapsed time, using Coordinated Universal Time or local time, which begins at midnight and ends 24 hours later at the next midnight. Duty period means the period of elapsed time between reporting for an assignment involving flight time and release from that assignment by the certificate bolder conducting domestic, flag, or supplemental operations. The time is calculated using either Coordinated Universal Time or local time to reflect the total elapsed time. Flight attendant means an individual, other than a flight crewmember, who is assigned by a certificate holder conducting domestic, flag, or supplemental operations, in accordance with the required minimum crew complement under the certificate bolder's operations specifications or in addition to that minimum complement, to duty in an aircraft during flight time and whose duties include but are not necessarily limited to cabin-safety-related responsibilities. Rest period means the period free of all restraint or duty for a certificate holder conducting domestic, flag, or supplemental operations and free of all responsibilities for work or duty should the occasion arise. A certificate holder conducting domestic, flag, or supplemental operations may assign a duty period to a flight attendant only when the following applicable duty period limitations and rest requirements are met. A. Except as provided in paragraphs D, E, and F of this section, no certificate holder conducting domestic, flag, or supplemental operations may assign a flight attendant to a scheduled duty period of more than 14 hours. B. Except as provided in paragraph C of this section, a flight attendant scheduled to a duty period of 14 hours or less as provided under paragraph A of this section must be given a scheduled rest period of at least 9 consecutive hours. This rest period must occur between the completion ofthe scheduled duty period and the commencement of the subsequent duty period. C. The rest period required under paragraph B of this section may be scheduled or reduced to 8 consecutive hours if the flight attendant is provided a subsequent rest period of at least 10 consecutive hours; this subsequent rest period must be scheduled to begin no later than 24 hours after the beginning of the reduced rest period and must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. D. A certificate holder conducting domestic, flag, or supplemental operations may assjgn a flight attendant to a scheduled duty period of more than 14 hours, but no more than 16 hours, if the certificate holder has assigned to the flight or flights in that duty period at least one flight attendant in addition to the minimum flight attendant complement required for the flight or flights in that duty period under the certificate holder's operations specifications. E. A certificate holder conducting domestic, flag, or supplemental operations may assign a flight attendant to a scheduled duty period of more than 16 hours, but no more than 18 10
hours, if the certificate holder has assigned to the flight or flights in that duty period at least two flight attendants in addition to the minimum flight attendant complement required for the flight or flights in that duty period under the certificate holder's operations specifications. F. A certificate holder conducting domestic, flag, or supplemental operations may assign a flight attendant to a scheduled duty period of more than 18 hours, but no more than 20 hours, if the scheduled duty period includes one or more flights that land or take off outside China, and if the certificate holder has assigned to the flight or flights in that duty period at least three flight attendants in addition to the minimum flight attendant complement required for the flight or flights in that duty period under the domestic certificate holder's operations specifications. G Except as provided in paragraph H of this section, a flight attendant scheduled to a duty period of more than 14 hours but no more than 20 hours, as provided in paragraphs D, E and F of this section, must be given a scheduled rest period of at least 12 consecutive hours. This rest period must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. H. The rest period required under paragraph G of this section may be scheduled or reduced to 10 consecutive hours if the flight attendant is provided a subsequent rest period of at least 14 consecutive hours; this subsequent rest period must be scheduled to begin no later than 24 hours after the beginning of the reduced rest period and must occur between the completion of the scheduled duty period and the commencement of the subsequent duty period. I. Notwithstanding paragraphs D, E, and F of this section, if a certificate holder conducting domestic, flag, or supplemental operations elects to reduce the rest period to 10 hours as authorized by paragraph H of this section, the certificate holder may not schedule a flight attendant for a duty period of more than 14 hours during the 24-hour period commencing after the beginning of the reduced rest period. J. No certificate holder conducting domestic, flag, or supplemental operations may assign a flight attendant any duty period with the certificate holder unless the flight attendant has had at least the minimum rest required under this section. K. No certificate holder conducting domestic, flag, or supplemental operations may assign a flight attendant to perfonn any duty with the certificate holder during any required rest period.. L. Time spent in transportation, not local in character, that a certificate bolder conducting domestic, flag, or supplemental operations requires of a flight attendant and provides to transport the flight attendant to an airport at which that flight attendant is to serve on a flight as a crewmember, or from an airport at which the flight attendant was relieved from duty to return to the flight attendant's home station, is not considered part of a rest period. M. Each certificate holder conducting domestic, flag, or supplemental operations must relieve 11
each flight attendant engaged in air transportation and each commercial operator must relieve each flight attendant engaged in air commerce from all further duty for at least 24 consecutive hours during any 7 consecutive calendar days. N. A flight attendant is not considered to be scheduled for duty in excess of duty period limitations if the flights to which the flight attendant is assigned are scheduled and normally terminate within the limitations but due to circumstances beyond the control of the certificate holder conducting domestic, flag, or supplemental operations (such as adverse weather conditions) are not at the time of departure expected to reach their destination within the scheduled time.
FL I GHT TIME L I MITAT IONS AND REST REQUIREMENTS: DOMEST I C, FLAG, OR SUPPLEMENTAL OPERATIONS Domestic Operations: All Flight Crewmembers No certificate holder conducting domestic operations may schedule any flight crewmember and no flight crewmember may accept an assignment for flight time in scheduled air transportation or in other commercial flying if that crewmember's total flight time in all commercial flying will exceed 1 000 hours in any calendar year, or 90 hours in any calendar month, or 35 hours in any 7 consecutive calendar days (but this period of time may be extended to 40 hours, provided each crewmember could have a chance to take a rest in an approved area of sleep during each period of flight), or 8 hours between required rest periods. 1) Except as provided in paragraph 2) of this section, no certificate holder conducting
domestic operations may schedule a flight crewmember and no flight crewmember may accept an assignment for flight time during the 24 consecutive hours preceding the scheduled completion of any flight segment without a scheduled rest period during that 24 hours of at least the following:
A. 9 consecutive hours of rest for less than 8 hours of scheduled flight time. B. 10 consecutive hours of rest for 8 or more but less than 9 hours of scheduled fl ight time. C. 11 consecutive hours of rest for 9 or more hours of scheduled flight time. 2) A certificate holder may schedule a flight crewmember for less than the rest required in
paragraph l) of this section or may reduce a scheduled rest under the following conditions:
A. A rest required under paragraph 1) A of this section may be scheduled for or reduced to a minimum of 8 hours if the flight crewmember is given a rest period of at least 10 hours that must begin no later than 24 hours after the commencement of the reduced rest period. B. A rest required under paragraph 1) B of this section may be scheduled for or reduced to a minimum of 8 hours if the flight crewmember is given a rest period of at least 11 hours that must begin no later than 24 hours after the commencement of the reduced rest period. C. A rest required under paragraph 1) C of this section may be scheduled for or reduced to a minimum of 9 hours if the flight crewmember is given a rest period of at least 12 hours that 12
must begin no later than 24 hours after the commencement of the reduced rest period. D. No certificate holder may assign, nor may any flight crewmember perform any flight time with the certificate holder unless the flight crewmember has had at least the minimum rest required under this passage. 3)Each certificate holder conducting domestic operations shall relieve each flight crewmember engaged in scheduled air transportation from all further duty for at least 36 consecutive hours during any 7 consecutive days. 4) No certificate holder conducting domestic operations may assign any flight crewmember and no flight crewmember may accept assignment to any duty with the air carrier during any required rest period. 5) Time spent in transportation, not local in character, that a certificate holder requires of a flight crewmember and provides to transport the crewmember to an airport at which he is to serve on a flight as a crewmember, or from an airport at which he was relieved from duty to return to his home station, is not considered part ofa rest period. 6) A flight crewmember is not considered to be scheduled for flight time in excess of flight time limitations if the flights to which he is assigned are scheduled and normally terminate within the limitations, but due to circumstances beyond the control of the certificate holder (such as adverse weather conditions), are not at the time of departure expected to reach their destination within the scheduled time. In this case, the excess part of duty time should not in any circumstances exceed 2 hours.
Flag Operations One or 1\vo Pilot Crews A certificate holder conducting flag operations may schedule a pilot to fly in an airplane that has a crew of one or two pilots for 8 hours or less during any 24 consecutive hours without a rest period during these 8 hours.
If a certificate holder conducting flag operations schedules a pilot to fly more than 8 hours during any 24 consecutive hours, it shall give him an intervening rest period, at or before the end of 8 scheduled hours of flight duty. This rest period must be at least twice the number of hours flown since the preceding rest period, but not less than 8 hours. The certificate holder shall relieve that pilot of all duty with it during that rest period. Each pilot who has flown more than 8 hours during 24 consecutive hours must be given at least 18 hours of rest before being assigned to any duty with the certificate holder. No pilot may fly more than 35 hours during any 7 consecutive days, and each pilot must be relieved from all duty for at least 36 consecutive hours at least once during any 7 consecutive days. No pilot may fly as a member of a crew more than 90 hours during any one calendar month. No pilot may fly as a member of a crew more than 1 000 hours during any 12-calendar-month period.
Two Pilots and One Additional Flight Crewmember No certificate holder conducting flag operations may schedule a pilot to fly, in an airplane that 13
has a crew of two pilots and at least one additional flight crewmember, for a total of more than 12 hours during any 24 consecutive hours. If a pilot has flown 20 or more hours during any 48 consecutive hours or 24 or more hours during any 72 consecutive hours, he must be given at least 18 hours of rest before being assigned to any duty with the air carrier. In any case, he must be given at least 36 consecutive hours of rest during any 7 consecutive days. No pilot may fly as a flight crewmember more than 120 hours during any 30 consecutive days or 300 hours during any 90 consecutive days, or 1 000 hours during any 12-calendar-month period.
Three or More Pilots and an Additional Flight Crewmember Each certificate holder conducting flag operations shall schedule its flight hours to provide -adequate rest periods on the ground for each pilot who is away from his base and who is a pilot on an airplane that has a crew of three or more pilots and an additional flight crewmember. It shall also provide adequate sleeping quarters on the airplane whenever a pilot is scheduled to fly more than 12 hours during any 24 consecutive hours. The certificate holder conducting flag operations shall give each pilot, upon return to his base from any flight or series of flights, a rest period that is at least twice the total number of hours he flew since the last rest period at his base. During the rest period required by this paragraph, the air carrier may not require him to perform any duty for it. If the required rest period is more than 7 days, that part of the rest period in excess of 7 days may be given at any time before the pilot is again scheduled for flight duty on any route. No pilot may fly as a flight crewmember more than 350 hours during any 90 consecutive days, or 1 000 hours during any 12-calendar-month period. Pilots Not Regularly Assigned A. Except as provided in paragraphs B through E of this part, a pilot who is not regularly assigned as a flight crewmember for an entire calendar month may not fly more than 90 hours in any 30 consecutive days. B. The monthly flight time limitations for a pilot who is scheduled for duty aloft for more than 20 hours in two-pilot crews in any calendar month, or whose assignment in such a crew is interrupted more than once in that calendar month by assignment to a crew consisting of two or more pilots and an additional flight crewmember, are those set forth in the passage above titled "One or Two Pilot Crews". C. Except for a pilot covered by paragraph B of this part, the monthly and quarterly flight time limitations for a pilot who is scheduled for duty aloft for more than 20 hours in two-pilot and additional flight crewmember crews in any calendar month, or whose assignment in such a crew is interrupted more than once in that calendar month by assignment to a crew consisting of three pilots and additional flight crewmember, are those set forth in the passage above titled "Two Pilots and One Additional Flight Crewmember".
D. The quarterly flight time limitations for a pilot to whom paragraphs Band C of this part do 14
not apply and who is scheduled for duty aloft for a total of not more than 20 hours within any calendar month in two-pilot crews (with or without additional flight crewmembers) are those set forth in the passage above titled ''Three or More Pilots and an Additional Flight Crewmember" . E. The monthly and quarterly flight time limitations for a pilot assigned to each of two-pilot, two-pilot and additional flight crewmember, and three-pilot and additional flight crewmember crews in a given calendar month, and who is not subject to paragraph B, C, or D of this part, are those set forth in the passage above titled "Two Pilots and One Additional Flight Crewmember". No pilot that is employed as a pilot by a certificate holder conducting flag operations may do any other commercial flying if that commercial flying plus his flying in air transportation will exceed any flight time limitation in this part Time spent in deadhead transportation to or from duty assignment is not considered to be a part of a rest period.
In any operation in which one flight engineer or flight navigator is required, the flight time limitations in the passage above titled "Two Pilots and One Additional Flight Crewmember"
In
apply to that flight engineer or flight navigator. any operation in which more than one flight engineer or flight navigator is required, the flight time limitations in the passage above titled "Three or More Pilots and an Additional Flight Crewmember'' apply to those flight engineers or flight navigators.
Supplemental Operations
Pilots: Airplanes A certificate holder conducting supplemental operations may schedule a pilot to fly in an airplane for 8 hours or less during any 24 consecutive hours without a rest period during those 8 hours. If the flight is in an airplane with a pressurization system that is operative at the beginning of the flight, and the flight crew consists of at least two pilots and a flight engineer, and the certificate holder uses, in conducting the operation, an air/ground communication service that is independent of systems operated by China, and a dispatch organization, both of which are approved by the Administrator as adequate to serve the terminal points concerned, the certificate holder may, in conducting a nonstop flight, schedule a flight crewmember for more than 8 but not more than 10 hours of continuous duty aloft without an intervening rest period. Each pilot who has flown more than 8 hours during any 24 consecutive hours must be given at least 16 hours of rest before being assigned to any duty with the certificate holder. Each certificate holder conducting supplemental operations shall relieve each pilot from all duty for at least 36 consecutive hours at least once during any 7 consecutive days. No pilot may fly as a crewmember in air transportation more than 90 hOl;lfS during any 30 consecutive days. No pilot may fly as a crewmember in air transportation more than 1 000 hours during any calendar year. 15
In any operation in which one flight engineer is serving, those flight time limitations above in this section are also applied to that flight engineer.
Two Pilot Crews: Airplanes If a certificate holder conducting supplemental operations schedules a pilot to fly more than 8 hours during any 24 consecutive hours, it shall give him an intervening rest period at or before the end of 8 scheduled hours of flight duty. This rest period must be at least twice the number of hours flown since the preceding rest period, but not less than 8 hours. The certificate holder conducting supplemental operations shall relieve that pilot of all duty with it during that rest period. No pilot of an airplane that has a crew of two pilots may be on duty for more than 16 hours during any 24 consecutive hours. In any operation in which one flight engineer is serving, those flight time limitations above in this section are also applied to that flight engineer. Three Pilot Crews: Airplanes No certificate holder conducting supplemental operations may schedule a pilot for flight deck duty in an airplane that has a crew of three pilots for more than 8 hours in any 24 consecutive hours, or to be aloft in an airplane that has a crew of three pilots for more than 12 hours in any 24 consecutive hours. No pilot of an airplane that has a crew ofthree pilots may be on duty for more than 18 hours in any 24 consecutive hours. Four Pilot Crews: Airplanes No certificate holder conducting supplemental operations may schedule a pilot for flight deck duty in an airplane that has a crew of four pilots for more than 8 hours in any 24 consecutive hours, or to be aloft in an airplane that has a crew of four pilots for more than 16 hours in any 24 consecutive hours. No pilot of an airplane that has a crew of four pilots may be on duty for more than 20 hours in any 24 consecutive hours. In any operation in which more than one flight engineer is serving and the flight crew contains more than two P.ilots, those flight time limitations above in this section are also applied to the flight engineers. No airman may be aloft as a flight crewmember for more than J 000 hours in any 12-calendar -month period. No airman who is employed by a certificate holder conducting supplemental operations may do any other commercial flying, if that commercial flying plus his flying in operations under this part will exceed any flight time limitation in this part. Time spent by an ainnan in deadhead transportation to or from a auty assignment is not considered to be part of any rest period.
Crew ofTwo Pilots and One Additional Airman as Required No certificate holder conducting supplemental operations may schedule an ainnan to be aloft
16
::nember of the flight crew in an airplane that has a crew of two pilots and at least one additional ilig.:l~ cre'w\'Dlember for more than 12 hours during any 24 consecutive hours. If an airman has been aloft as a member of a flight crew for 20 or more hours during any 48 consecutive hours or 24 or more hours during any 72 consecutive hours, be must be given at least l8 hours of rest before being assigned to any duty with the certificate holder. In any case, he must be relieved of all duty for at least 24 consecutive hours during any 7 consecutive days. No airman may be aloft as a flight crewmember for more than 120 hours during any 30 consecutive days, or 300 hours during any 90 consecutive days. Crew ofThree or More Pilots and Additional Airmen as Required No certificate holder conducting supplemental operations may schedule an airman for flight deck duty as a flight engineer, a navigator or a batman in a crew of three or more pilots and additional ainnen for a total of more than 14 hours during any 24 consecutive hours. Each certificate holder conducting supplemental operations shall schedule its flight hours to provide adequate rest periods on the ground for each airman who is away from his principal operations base. It shall also provide adequate sleeping quarters on the airplane whenever an airman is scheduled to be aloft as a flight crewmember for more than 12 hours during any 24 consecutive hours. No certificate holder conducting supplemental operations may schedule any flight crewmember to be on continuous duty for more than 30 hours. Such a crewmember is considered to be on continuous duty from the time he reports for duty until the time he is r~leased from duty for a rest period of at least 10 hours on the ground. If a flight crewmember is on continuous duty for more than 24 hours (whether scheduled or not) during any scheduled duty period, he must be given at least 16 hours for rest on the ground after completing the last flight scheduled for that scheduled duty period before being assigned any further flight duty. If a flight crewmember is required to engage in deadhead transportation for more than 4 hours before beginning flight duty, one half of the time spent in deadhead transportation must be treated as duty time for the purpose of complying with duty time limitations, unless be is given at least 10 hours of rest on the ground before being assigned to flight duty. Each certificate holder conducting supplemental operations shall give each airman, upon return to his operations base from any flight or series of flights, a rest period that is at least twice the total number of hours he was aloft as a flight crewmember since the last rest period at his base, before assigning him to any further duty. If the required rest period is more than 7 days, that part of the rest period that is more than 7 days may be given at any time before the pilot is again scheduled for flight duty. No ainnan may be aloft as a flight crewmember for more than 350 hours in any 90 consecutive days. Pilots Serving in More Than One Kind ofFlight Crew This passage applies to each pilot assigned during any 30 consecutive days to more than one type of flight crew.
!S !
17
The flight time limitations for a pilot who is scheduled for duty aloft for more than 20 hours in two-pilot crews in 30 consecutive days, or whose assignment in such a crew is interrupted more than once in any 30 consecutive days by assignment to a crew of two or more pilots and an additional flight crewmember, are those listed in the passage titled "Pilots: Airplanes" through the passage titled "Four Pilot Crews: Airplanes" in the part of "Supplemental Operations", as appropriate. Except for a pilot covered by the paragraph above of this passage, the flight time limitations for a pilot scheduled for duty aloft for more than 20 hours in two-pilot and additional flight crewmember crews in 30 consecutive days or whose assignment in such a crew is interrupted more than once in any 30 consecutive days by assignment to a crew consisting of three pilots and an additional flight crewmember, are those set forth in the passage titled "Crew of Two Pilots and One Additional Airman As Required" in the part of "Supplemental Operations". The flight time limitations for a pilot to whom paragraphs above of this section do not apply, and who is scheduled for duty aloft for a total of no more than 20 hours within 30 consecutive days
in two-pilot crews (with or without additional flight crewmembers) are those set forth in the passage titled "Crew of Three or More Pilots and Additional Airmen As Required" in the part of "Supplemental Operations". The flight time limitations for a pilot assigned to each of two-pilot, two-pilot and additional flight crewmember, and three-pilot and additional flight crewmember crews in 30 consecutive days, and who is not subject to the paragraphs above of this passage, are those listed in the passage titled "Crew of Three or More Pilots and Additional Airmen As Required" in the part of "Supplemental Operations".
AIRCRAFT DISPATCHER DUTY TIME LIMITATIONS No domestic or flag carrier may schedule a dispatcher to be on duty for more than 10 consecutive hours. If a dispatcher is scheduled for more than 10 hours of duty in 24 consecutive hours, he/she must be given at least 8 hours of rest at or before the end of 10 consecutive hours of duty. A dispatcher must be relieved of all duty with the carrier for at least 24 consecutive hours in any 7 consecutive days. Each certificate holder conducting domestic or flag operations shall establish the daily duty period for a dispatcher so that it begins at a time that allows him or her to become thoroughly familiar with existing and anticipated weather conditions along the route before he or she dispatches any airplane. He or she shall remain on duty until each airplane dispatched by him or her has completed its flight, or has gone beyond his or her jurisdiction, or until he or she is relieved by another qualified dispatcher. Except in cases where circumstances or emergency conditions beyond the control of the certificate holder require otherwise, no certificate holder conducting domestic or flag operations may schedule a dispatcher for more than 10 consecutive hours of duty. If a dispatcher is scheduled
18
: - -::Jre than 10 hours of duty in 24 consecutive hours, the certificate holder shall provide him or ~ ; rest period of at least 8 hours at or before the end of 10 hours of duty. Each dispatcher must be ~~- ed of all duty with the certificate holder for at least 24 consecutive hours during any 7 -=u..:;...."1:utive days or the equivalent thereof within any calendar month. ~otwithstanding paragraphs above of this section, a certificate bolder conducting flag --:~:ions may, if authorized by the Administrator, schedule an aircraft dispatcher at a duty station ~.je China, for more than 10 consecutive hours of duty in a 24-hour period if that aircraft ~-;atcher is relieved of all duty with the certificate bolder for at least 8 hours during each 24-hour :-=::c-d.
SECTION G DISPATCHING AND FLIGHT RELEASE Operational control with respect to a flight, means the exercise of authority over initiating, :c.:ducting or terminating a flight. For operations of supplemental air carriers or commercial operators, the pilot-in-command and :::: director of operations are jointly responsible for the initiation, continuation, diversion, and ·!::llination of a flight. Each flag and domestic flight must have a dispatch release on board. The dispatch release of a --~; or domestic air carrier may be in any form but must contain at least the following information ; ::::erning the flight: A. The identification number of the aircraft; B. The trip number; C. The departure, destination, intermediate and alternate airports; D. The type of operation (IFR or VFR); E. The minimum fuel supply. It may include any additional available weather reports or forecasts that the pilot-in-command :: :he aircraft dispatcher considers necessary or desirable. Each supplemental carrier or commercial operator flight must have a flight release on board. :-.1e flight release can be in any form but must contain the following information: A. The company or organization name; B. Make, model and registration number of the aircraft used; C. The flight or trip number and the date of the flight; D. The name of each flight crewmember, flight attendant and the pilot designated as pilot-incommand; E. The departure, destination, intermediate and alternate airports and route; F. The type of operation (e.g., IFR or VFR); G. The minimum fuel supply; H. The latest weather reports and forecasts for the complete flight (may be attached to the 19
release rather than be part of it). The aircraft dispatcher must provide the pilot-in-command with all available current reports or information on airport conditions and irregularities of navigation facilities that may affect the safety of flight; must provide the pilot-in-command with all available weather reports and forecasts of weather phenomena that may affect the safety of flight including adverse weather; and must update this information during a flight. When a domestic flight lands at an intermediate airport named in its original dispatch release and departs again within 1 hour, it does not need a new dispatch release. lf it remains on the ground for more than 1 hour, a redispatch release must be issued. When a flag flight lands at an intermediate airport named in its original dispatch release and departs again within 6 hours, it does not need a new dispatch release. If it remains on the ground for more than 6 hours, a redispatch is required. No person may continue a flag air carrier flight from an intermediate airport without redispatch if the airplane has been on the ground for more than 6 hours. The pilot-in-command shall carry in the airplane to its destination: load manifest, flight release, airworthiness release, pilot route certification, and flight plan. The air carrier must keep copies of these documents for at least 3 months. Each certificate holder conducting domestic, flag, or commuter operations must obtain operations specifications containing authorization and limitations for routes and areas of operations. A provisional airport is defined as an airport approved by the Administrator for use by a certificate holder for the purpose of providing service to a community when the regular airport used by the certificate holder is not available. Each certificate holder conducting domestic, flag, or conunuter operations must obtain operations specifications containing, among many other provisions, the kinds of operations authorized. A supplemental air carrier must retain a copy of each load manifest, flight release and flight plan at its principal operations base for at least 3 months.
SECTION H
FUEL REQUIREMENTS
All domestic flights must have enough fuel to: A. Fly to the airport to which the flight was dispatched; B. Thereafter, fly to and land at the most distant alternate airport (if an alternate is required) for the airport to which dispatched; and C. Thereafter, fly for 45 minutes at noonal cruising fuel consumption. Certificate holders who are authorized by CAAC can determine the fuel requirement by means of flying from specified airport to alternate. No person may dispatch or take off an airplane unless it has enough fuel to fly from the specified airport to and land at an alternate airport, and thereafter fly for 45 minutes at normal cruising fuel consumption. But the fuel quantity is not less than the
20
~-..±ement
to fly to destination dispatched, and thereafter fly for 2 hours at normal cruising fuel
:\!~:Imption.
The fuel required for a flag flight landing within the contiguous China is the same as for ::J: :::estic flights. ~onturbine and turbo-propeller-powered airplanes flight (with an alternate available) landing :..::side the contiguous China must have enough fuel to: A. Fly to and land at the airport to which it is dispatched; B. Thereafter, fly to and land at the most distant alternate airport specified in the dispatch release; and C. Thereafter, fly for 30 minutes plus 15 percent of the total time required to fly at normal cruising fuel consumption to the airports specified in paragraphs 1 and 2 of this section or to fly for 90 minutes at normal cruising fuel consumption, whichever is less. No person may dispatch a nonturbine or turbo-propeller-powered airplane to an airport for ·.vhlch an alternate is not specified, unless it has enough fuel, considering wind and forecast weather conditions, to fly to that airport and thereafter to fly for 3 hours at normal cruising fuel consumption. Turbojet-engine-powered air carrier airplanes, other than turbo propeller, flight (with an alternate available) landing outside the contiguous China must have fuel to: A. Fly to the destination, then B. Fly 10% of the total time required to fly to the destination, then C. Fly to and land at the most distant alternate, then D. Fly for 30 minutes at holding speed at 1 500 feet above the alternate. No person may release a turbine-engine powered airplane (other than a turbo-propeller airplane) to an airport for which an alternate is not specified unless it has enough fuel, considering wind and other weather conditions expected, to fly to that airport and thereafter to fly for at least 2 hours at normal cruising fuel consumption.
SECTION I CARRIAGE OF PASSENGERS AND CARGO Before take-off all the passengers must be briefed on: A. Smoking; B. The location of emergency exits; C. The use of seatbelts; D. The location and use of any required means of emergency flotation. After the seatbelt sign has been turned off in flight, the passengers must be briefed to keep their seatbelts fastened while seated. In addition to the required briefings, passengers must be provided with printed cards that contain diagrams of and methods of operating the emergency exits and the use of other emergency equipment. Before flight is conducted above FL250, a crewmember 21
must instruct the passengers on the necessity of using oxygen in the event of cabin depressurization, and must point out to them the location and demonstrate the use of the oxygen dispensing equipment Each passenger two years old and older must have their own seat or berth and approved seatbelt During take-off and landing, all passengers must be in their seat with their seatbelts fastened. A child under two may be held by an adult. During the en route portion of a flight, two passengers may share a seatbelt while seated in a multiple lounge or divan seat. There are certain persons who have to be admitted to the flight deck in flight (such as crewmembers, CAAC inspectors, etc.) and certain others who may be admitted (e.g., deadheading crew), but the pilot-in-command has emergency authority to exclude any person from the flight deck in the interest of safety. Law enforcement officers may carry firearms on board an air carrier flight if their duties so require. Except in an emergency, the carrier should be given at least one hour prior notice that a person carrying a deadly weapon is going to be on the flight. If a passenger is carrying a firearm in their checked baggage, the weapon must be unloaded and the bag locked. The passenger must retain the key to the bag. The bag must be stowed in a portion ofthe aircraft that is inaccessible to both the passenger and to crewmembers in flight. Prisoners are sometimes carried on air carrier flights. The prisoners are always escorted and no more than one prisoner who is classified as "maximum risk" can be allowed on the aircraft. Certain rules apply to the carriage of prisoners. These include: A. The prisoner and escort must be boarded before all other passengers and must stay on board until all other passengers have deplaned. B. The prisoner and escort must sit in the most rearward passenger seats and the escort must sit between the prisoner and the aisle. C. The carrier may serve the prisoner and the escort food and beverages, but neither of them may be served alcohol. If a person who appears to be intoxicated creates a disturbance on a flight, a report of the incident must be made to the Administrator (the CAAC) within 5 days. Certain passengers may be carried on an all-cargo flight without the carrier having to comply with all the passenger-carrying rules. Passengers carried on an all-cargo flight must have a seat with an approved seatbelt in the cargo compartment. They must have access to the pilot compartment or to an exit. The pilot-in-command must be able to notify them when they must have their seatbelt fastened and when smoking is prohibited. They must receive an emergency briefmg from a crewmember prior to take-off. The pilot-in-command may authorize the passenger to be admitted to the flight crew compartment Cargo (including carry-on baggage) may be carried in the passenger compartment of an aircraft if certain conditions are met If the cargo is carried in an approved cargo bin, it can be located anywhere in the passenger compartment. The bin: A. Must withstand the load factor required of passenger seats multiplied by 1.15;
22
B. May not be installed in a position that restricts access to or use of any required emergency exit, or of the aisle in the passenger cabin; C. Must be completely enclosed and made of material that is at least flame resistant. If the cargo is not placed in an approved cargo bin it must be located aft of a bulkhead or divider (i.e., not aft of a passenger) and it must meet certain other requirements. These include: A. It must be properly secured by a safety belt or other tie down. B. It must be packaged or covered in a manner so as to avoid injury to occupants of the passenger cabin. C. It must not impose an excessive load on the floor or seat structures of the aircraft. D. Its location must not restrict access to or use of the aisle, any regular exit or any required emergency exit. E. Its location must not obscure any passenger's view of the "seatbelt", "no smoking" or required "exit" signs unless an auxiliary sign is installed. Each person who has duties concerning the handling or carriage of dangerous articles or magnetized materials must have completed a training course within the preceding 12 calendar months.
SECTION J EMERGENCY EQUIPMENT AND OPERATIONS Certain emergency equipment must be carried on every air carrier airplane. This equipment includes fire extinguishers, megaphones, first aid kits and a crash ax. All this equipment must: A. Be inspected regularly. B. Be readily accessible to the crew and, for items carried in the passenger cabin, to the passengers. C. Be clearly identified and marked with its method of operation (this applies to any containers in which the equipment is carried). Only one crash ax is required on the airplane and must be carried on the flight deck. At least one hand fire extinguisher must be carried on the flight deck. The number of extinguishers carried 2
the cabin is determined by the number of installed passenger seats. The following table applies. Minimum Number ofHand Fire Extinguishers in the Passenger Cabin Passenger Seating Capacity Extinguishers Required 6 through 30
1
31 through 60
2
61 through 200
3
201 through 300
4
301 through 400
5
401 through 500
6 23
501 through 600 7 601 or more 8 The number of megaphones carried on the airplane is determined by the number of installed passenger seats. On airplanes with a seating capacity of 60 through 99 passengers, one megaphone must be carried in the most rearward location in the passenger cabin that is readily accessible to a normal flight attendant seat. On airplanes with a seating capacity of 100 or more seats, one megaphone must be carried at the rear of the cabin and another megaphone must be carried at the front of the cabin. Passenger carrying airplanes must have an emergency exit light system. This system must be operable manually from both the flight crew station and from a point in the passenger compartment readily accessible to a flight attendant When the system is armed it must come on automatically with the interruption of the airplane's nonnal electrical power. The exit lights must be armed or turned on during taxiing, take~off and landing. Every emergency exit (other than an over wing exit) that is more than 6 feet from the ground must have a means of assisting occupants to the ground in the event of an emergency evacuation. The most common means of complying with this requirement is an inflatable slide that deploys automatically when the door is opened. If such an automatic escape slide is installed, it must be armed during taxiing, take-off and landing. If any required emergency exit for passengers is located in other than the passenger compartment (such as the flight deck), the door separating the compartments must be latched open during take-off and landing. A public address system and a separate crewmember interphone system must be installed on all airplanes with a seating capacity of more than 19 seats. Each crewmember on a flight must have a flashlight in good working order readily available. When operating at flight altitudes above 10 000 feet there must be enough oxygen for all crewmembers for the entire flight at those altitudes, and in no event less than a 2~hour supply. When operating at flight altitudes above FL250 each flight crewmember on flight deck duty must have an oxygen mask, within immediate reach, so designed that it can be rapidly placed on his/her face. This is commonly referred to as a "quick-donning" oxygen mask. To meet the requirements, regulations require that the mask be designed so that it can be put on the user's face within 5 seconds. If, while operating above FL250, one pilot leaves his/her station, the other pilot must put on his/her oxygen mask. Above FL41 0 one pilot must wear his/her mask at all times. Notice that the rule applies only to the pilots. Above FL250 the flight engineer need only have a quick-donning mask readily available. The oxygen requirements for passengers vary with the type of aircraft but oxygen must be provided to all passengers for the entire time the cabin altitude is above 15 000 feet Passengers on turbine powered airplanes must be supplied oxygen according to the following schedule. A. For flights at cabin pressure altitudes above 10 000 feet, up to and including 14 000 feet, there must be enough oxygen to supply 10% of the passengers for any time at those altitudes in excess of 30 minutes. 24
..... ?or flights at cabin pressure altitudes above 14 000 feet, up to and including 15 000 feet,
:1ere must be enough oxygen for 30% of the passengers for the entire time of flight at :hose altitudes. C For flights at cabin pressure altitudes above 15 000 feet there must be enough oxygen for all the passengers for the entire time of flight at those altitudes. ::~e amount of oxygen carried for passengers in the event of loss of pressurization varies ~-=::jing on the ability of the airplane to make an emergency descent. If the aircraft can make a .:esc~m to 14 000 feet within 4 minutes it may caoy less oxygen than would otherwise be required . .-\ certain amount of first aid oxygen must be carried for passengers on flights that operate ~ :x·.e FL250. The amount of oxygen is determined by the actual number of passengers but in no ::~ may there be less than 2 oxygen dispensing units. On extended over-water flights (more than 50 nautical miles from the shoreline) the airplane =.m have a life preserver for each occupant of the aircraft, and enough life rafts to accommodate ~: :he occupants. This equipment must be easily accessible in the event of a ditching. A. Each life raft and each life vest must be equipped with a survivor locator light. B. A survival kit, appropriate for the route flown, must be attached to each life raft. C. There must be at least one portable emergency radio transmitter carried on the airplane. When flag or supplemental carriers or commercial operators fly over uninhabited terrain, the :""o:Iowing survival equipment must be carried on the airplane: A. Suitable pyrotechnic signaling devices; B. A survival-type emergency locator transmitter; C. Enough survival kits, appropriate for the route flown, for all the occupants of the airplane. In an emergency situation that requires immediate decision and action, the pilot-in-command u:ay take any action that he/she considers necessary under the circumstances. In such a case the PIC ::1ay deviate from prescribed procedures and methods, weather minimums and regulations to the ;:x1ent required in the interest of safety. In an emergency situation arising during flight that requires ~ediate decision and action by an aircraft dispatcher, the dispatcher must advise the :ilot-in-command of the emergency, shall ascertain the decision of the pilot-in-command and shall -:ave that decision recorded. If the dispatcher cannot communicate with the pilot, he/she shall :eclare an emergency and take any action he/she considers necessary under the circumstances. Each certificate holder (airline) must, for each type and model of airplane, assign to each ::ategory of crewmember, as appropriate, the necessary functions to be performed in an emergency : ~ in a situation requiring emergency evacuation. The certificate holder must describe those duties ..:: its manual. Crewmembers must receive emergency training annually on several subjects. Besides the ::-aini.ng they must perform emergency drills in: A. The operation of emergency exits; B. Hand fire extinguishers; C. The emergency oxygen system and protective breathing equipment; 25
D. Donning. inflation and use of individual flotation equipment; and E. Ditching. Crewmembers who serve above 25 000 feet must receive instruction in hypoxia, respiration and decompression. Crewmembers must actually operate certain emergency equipment in their recurrent training at least once every 24 months. The pilot-in-command must make a report to the ATC and dispatcher of the stoppage of an engine's rotation in flight (due either to failure or intentional shutdown) as soon as practicable and must keep the ATC and dispatcher infonned of the progress of the flight. As a general rule, when an engine fails or is shutdown, the pilot-in-command must land the aircraft at the nearest suitable airport, time-wise, at which a safe landing can be made. There is an exception to the rule for airplanes with 3 or more engines. If only 1 engine has failed, the pilot-in-command may elect to continue to a more distant airport (possibly the original destination) if this is considered as safe as landing at the nearest suitable airport. The certificate holder must provide a cockpit check procedure (checklist) for each type of aircraft it operates. The procedures must include each item necessary for flight crewmembers to check for safety before starting engines, taking-off or landing, and in engine and systems emergencies. The procedures must be designed so that a flight crewmember will not need to rely on memory for items to be checked. The flight crew must use the approved check procedure. Whenever a pilot-in-command exercises emergency authority, he/she shall keep the appropriate ATC (Air Traffic Control) facility and dispatch centers fully infonned of the progress of the flight. A pilot-in-command declaring the emergency must send a written report to the air carrier's operations manager after the flight is completed. The operation's manager must send this report to the CAAC within 10 days after the pilot returning to his/her home base. When ATC gives priority to an aircraft in an emergency, the chief of the ATC facility involved may ask the pilot-in-command to submit a report. If asked, the pilot-in-command must submit a detailed written report to the ATC facility manager within 48 hours. This is required whether or not there was a deviation from regulations.
26
CHAPTER 2 EQUIPMENT, NAVIGATION AND FACILITIES SECTION A
INOPERATIVE EQUIPMENT
Each certificate holder's manual must contain en route flight, navigation, and communication ::ocedures for the dispatch, release or continuance of flight if any item of equipment required for ":-1e particular type of operation becomes inoperative or unserviceable en route. When any required instrument or equipment in an aircraft is inoperative, the airplane cannot be :lown unless that aircraft's minimum equipment list (MEL) allows such a flight. No person may take off any aircraft with inoperable instruments or equipment installed unless 2..."1 approved MEL exists for the aircraft. The MEL must provide for the operation of the aircraft -•·ith instruments and equipment in an inoperable condition. The pilot-in-command of an aircraft operating IFR in controlled airspace shall report to ATC ..:::1111ediately any malfunction of navigational, approach or communication equipment that occurs in :':ight The report must include: • Aircraft identification; • Equipment affected; • Degree to which the capability of the aircraft to operate IFR in the ATC system is impaired; and • Nature and extent of assistance desired from ATC.
SECTION 8
PITOT-STATIC INSTRUMENTS
Modem jet transports usually have three pitot-static systems. There are separate systems for :be captain's and co-pilot's instruments plus an auxiliary system that provides a backup for either of :be two primary systems. The instruments that require static pressure input are airspeed, Mach, ~titude and vertical speed indicators. In addition, the airspeed and Mach indicators need a source of ;-itot pressure. Besides the flight instruments, static pressure and pitot input is required for all those ~~·stems except for cabin differential pressure. The usual source for these non-flight instruments is :ie auxiliary pitot-static system. See Figure2- l in the following. 27
Altimeters compare the sea
level pressure setting in pressure window with the outside air pressure sensed through the static system. The difference is displayed as the altitude above sea level. Part of the preflight check is to verify the accuracy of the altimeters. An altimeter should be considered
questionable
if
the
indicated altitude varies by more than 75 feet from a known field elevation. The altimeter setting used by
Figurel-1 Typical Pltot-statlc System
pilots is always the station pressure of the reporting station corrected to sea level. Station pressure is the actual pressure at field elevation. The pressure measured at a station or airport is "station pressure, or the actual pressure at field elevation. True altitude is the actual height of the aircraft above
level. This is the same as indicated altitude when standard temperatures exist. When the temperature is warmer than standard, true se.J
altitude is higher than indicated altitude (approximately true altitude) that can be calculated but it is neither practical nor useful to do so in most situations. When setting an altimeter, a pilot should just use the appropriate altimeter setting and disregard the effects of nonstandard atmospheric pressures and temperatures. True altitude is indicated altitude corrected for the fact that nonstandard temperatures will result in nonstandard pressure lapse rates. In warm air, you fly at a true altitude higher than indicated. In cold air, you fly at a true altitude lower than indicated. Pressure altitude is the altitude indicated when the altimeter is set to the standard sea level pressure (29.92"Hg). In the United States, altimeters are always set to 29.92"Hg at and above 18 000 feet. This question assumes the difference between the pressure altitude and the indicated altitude (local altimeter setting) is not significant enough to reverse the effects of the temperature. Pressure altitude is the altitude indicated when the altimeter is set to the standard sea level
pressure of 29.92"Hg. Density altitude is used in aircraft performance computations. It is pressure altitude corrected for nonstandard temperatures. If the temperature is warmer than standard, density altitude will be higher than pressure altitude. The local altimeter setting is used when flying below FL180 and the altimeter 31.00"Hg or less. Special procedures apply when the local pressure is more than 3l.OO"Hg because most altimeters cannot be set higher than that In the United States, all altimeters are set to 29.92"Hg when climbing through FL180. Caution: outside the United States the transition altitude is often something other thanFL180. 28
-.. : .:-rnmon reason for altimeter errors is incorrect setting of the altimeter. If the setting in the -==-~~= is higher than the actual sea level pressure, the altimeter will read higher than the actual ~:
If the setting is too low, the altimeter will read lower than it really is. As a rough rule of ;::c::: :he magnitude of the error is about 1 000 feet for each 1"Hg that the altimeter is off. O::e inch ofHg pressure is equal to about 1 000 feet of altitude. In the United States, altimeters !:"e !..\\ays set to 29.92"Hg at and above 18 000 feet If the altimeter is not reset when descending :c::, ~'1 area with a local altimeter setting of 30.57"Hg, an error of 650 feet will result .:o 5-- 29.92 = 0.65"Hg = 650 feet). If the altimeter is set lower than the actual setting, it will read ~ ei than the actual altitude. Pilots should disregard the effect of nonstandard atmospheric temperatures and pressures :·,..:ept that low temperatures and pressures need to be considered for terrain clearance purposes. The airspeed indicators compare pitot pressure with static pressure and display the : _:Ierence as indicated airspeed. This indicated airspeed equals the aircraft's actual speed through
:::e air (True Airspeed) only under standard day conditions at sea level. Under almost all flight :vnditions, true airspeed will be higher than indicated airspeed because of the lower ambient ;:~ssures at altitude. The Mach meter displays aircraft speed as a percentage of the speed of sound. For example, ~
aircraft cruising at a Mach number of 0.82 is flying at 82% of the speed of sound. The Mach ~eter works in a manner similar to the airspeed indicator in which it compares pitot and static ;::-essure, but these inputs are corrected by an altimeter mechanism. If a pitot tube becomes blocked, the airspeed and Mach indicators will read inaccurately. If ~:essure is trapped in the pitot line, the airspeed will read inaccurately high as the aircraft climbs, .Jw as it descends, and will be unresponsive to changes in airspeed. The airspeed indicator acts as l::
altimeter because only the static pressure changes. This situation occurs in icing conditions if
:vth the ram air inlet and the drain bole of the pitot tube become completely blocked by ice.
If the pitot tube is blocked but the static port and the pitot drain hole remain open, the indicated :mspeed will drop to zero. The pitot tube drain hole allows the pressure in the pitot line to drop to =::nospheric and therefore there is no difference between the static and pitot pressures. If both the ram air input and the drain hole are blocked, the pressure trapped in the pitot line :.a1not change and the airspeed indicator may read as an altimeter. The airspeed will not change in -;vel flight even when the actual airspeed is varied by large power changes. During a climb the .:...-s;>eed indication will increase. During a descent the airspeed indication will decrease.
If the pitot tube becomes blocked but pressure is not trapped in the pitot lines, the indicated :_-s~ed will drop to zero since the pitot pressure will be approximately equal to the static pressure. Pitot tubes and static ports are electrically heated to prevent ice formations that could interfere .:=!proper operation of the systems. They are required to have "power on» indicator lights to show :::-~r
operation. In addition, many aircraft have an ammeter that shows the actual current flow to c::: ;.'itot and static ports. 29
Since the magnetic compass is the only direction-seeking instrument in most airplanes, the pilot must be able to turn the airplane to a magnetic compass beading and maintain this heading. It is influenced by magnetic dip which causes northerly turning error and acceleration/deceleration error. When northerly turning error occurs, the compass will lag behind the actual aircraft heading whlle turning through headings in the northern half of the compass rose, and lead the aircraft's actual heading in the southern half. The error is most pronounced when turning through north or south, and is approximately equal in degrees to the latitude. The acceleration/deceleration error is most pronounced on beadings of east and west When accelerating, the compass indicates a turn toward the north, and when decelerating it indicates a turn toward the south. No errors are apparent whlle on east or west headings, when turning either north or south.
SECTION C
SAFETY OF FLIGHT EQUIPMENT
Airborne weather radar is used to detect and avoid areas of heavy precipitation such as thunderstorms. With few exceptions, all air ·carrier aircraft must be equipped with an approved airborne weather radar unit. The radar must be in satisfactory operating condition prior to dispatch on an IFR or night VFR flight if thunderstorms (or other hazardous weather) that could be detected by the radar are forecast along the intended route of flight. An aircraft may be dispatched with an inoperative radar unit if one of two conditions is met: A. The flight will be able to remain in day VFR flight conditions, or B. Hazardous weather is not forecast An air carrier' operations manual must contain procedures for the flight crew to follow if the weather radar fails in flight. No person may dispatch an airplane under IFR or night VFR conditions when current weather reports indicate that thunderstorm, or other potentially hazardous weather conditions that can be detected with airborne weather radar, may reasonably be expected along the route to be flown, unless the weather radar is in satisfactory operating condition. If the airborne radar becomes inoperative en route, the airplane must be operated in accordance with the approved instructions and procedures specified in the operations manual for such an event. Return to the departure airport upon malfunction of airborne weather detection radar would be the correct action if it were the procedure specified in the air carrier's operations manual. However, it is not required by regulation.
A ground proximity warming system (GPWS) must be installed on all large turbinepowered airplanes. The GPWS gives aural and visual warnings when an aircraft too close to the terrain is in an improper configuration for landing, or when it deviates below glide slope on an ILS approach. No person may operate a turbine-powered airplane unless it is equipped with a ground
30
- - ' - -c ~~.::ling
glide slope deviation alerting system.
IC -\.5 I (Traffic Alert and Collision Avoidance System) provides proximity warning only, to :.:,.: :: _.:: in the visual acquisition of intruder aircraft. No recommended avoidance maneuvers
- ..!..~"'"- :e=. ::or authorized as a result of a TCAS I warning. TCAS ll provides traffic advisories ...... !..'
.:::
:-;solution advisories (RAS). Resolution advisories provide recommended maneuvers in
- ,__,. .:.:-ection to avoid conflicting traffic. TCAS does not alter or diminish the pilot's basic .......,...._,_-~-_• ~"':'
.:.::d responsibility to ensure safe flight After the conflict, return to the ATC clearance in
:: ::. ~e\'iation occurs, contact ATC as soon as practicable.
:;ilot who deviates from an ATC clearance in response to a TCAS n RAS shall notify ~: -: ~: deviation as soon as practicable and expeditiously return to the current ATC clearance ~ =:".;! :;affic conflict is resolved. ~::
Coch.-pit voice recorders are required on large turbine engine powered airplanes and large four e:-::-.a ".:.:'iprocating powered airplanes. The recorder must operate from before the start of the - -;
~ling
checklist to the completion of the secure cockpit checklist. Although the recorder
-:::::::: :':: ::1e entire flight, only the most recent 30 minutes of information need be retained on the "::.::1 a cockpit voice recorder is required on an airplane, it must be operated continuously
=c :::e
start of the use of the check list (before starting engines for the purpose of flight), to
~-=::.):1 =::::::::.::_~
:=
of the final checklist at the termination of flight Information recorded more than 30 wlier may be erased or otherwise obliterated.
..:....:: ;pproved flight recorder must be installed on all airplanes certified for operations above 0:( :'eet and on all turbine-powered airplanes. Whatever the flight recorder must varies from
'!::::::: ~e
:o airplane, but at a minimum it must record:
• :-i.me,
•
~ltirude,
• .~irspeed, • \'ertical acceleration, • Heading, and • :-ime of each radio transmission to or from ATC . .l.. !Otal of 1 hour of recorded data may be erased for the purpose of testing flight recorder
:::;.;t recorder system. Any erasure must be of the oldest recorded data accumulated at the -!
::·testing. :.:::ormation obtained from flight data and cockpit voice recorders is used to assist in
:::r.:=-=:."l..i.ng the cause of accidents or occurrences in connection with investigation under NTSB =:::.al Transportation Safety Board) Part 830. The Administrator does not use the cockpit voice ~~~:e:- record in any civil penalty or certificate action. ::: the event of an accident or occurrence requiring immediate notification to NTSB Part : . . .:..."1d that results in the termination of a flight, any operator who has installed approved
31
flight recorders and approved cockpit voice recorders shall keep the recorded information for at least 60 days.
SECTION D
COMMUNICATIONS
Each domestic and flag air carrier must show that a two-way air/ground radio communications system is available at points that will ensure reliable and rapid communications under normal operating conditions over the entire route (either direct or via approved point to point circuits) between each airplane and the appropriate dispatch office, and between each airplane and the appropriate air traffic control unit. The En Route Flight Advisory Service (Flight Watch) is a weather service on a common frequency of 122.0 MHz from selected FSS's (Flight Service Stations). This service is dedicated specifically to providing weather information to en route pilots and taking and disseminating pilot reports. Aeronautical weather and operational information may be displayed in the cockpit through the use of FAA FISDL (Federal Aviations Administration's Flight Information Services Data Link), and is designed to provide coverage throughout the continental U.S. from 5 000 feet AGL (above ground level) to 17 500 feet MSL (sea level), except in those areas where this is unfeasible due to mountainous terrain. FAA FISDL provides free of charge, the following basic products: METARS, SPECIS, TAFs and their amendments, SIGMETS, Convective SIGMETs, AIRMETs, PIREPs and, AWWs issued by the FAA or NWS (National Weather Service). FISDL products, such as ground-based radar precipitation maps, are not appropriate for use in tactical severe weather avoidance, such as negotiating a path through a weather hazard area (an area where a pilot cannot reliably divert around hazardous weather, such as a broken line of thunderstorms), but FISDL supports strategic weather decision making such as route selection to avoid a weather hazard area in its entirely flight. The misuse of information beyond its applicability may place the pilot and his/her aircraft in great jeopardy. In addition, FISDL should never be used in lieu of an individual preflight weather and flight planning briefing.
SECTION E NAVIGATION EQUIPMENT When an aircraft is flown IFR or VFR Over-the-Top it must have a dual installation of the navigation radios required to fly that route. This means that an aircraft flying Victor airways or jet routes must have two operable VOR systems. Only one ILS system and one marker beacon system are required. 32
"'o person may operate IFR or VFR Over-the-Top unless the airplane is equipped with the ~=
equipment necessary for the route, and is able to satisfactorily receive radio navigational _ -:- • s from all primary en route and approach navigational facilitates intended for use, by either of - : ~jependent systems. \\ben an aircraft is navigating over routes using low frequency, ADF or Radio Range, it only ~.:s one receiver for those NAVAIDS. If it is also equipped with two VOR receivers, if that is the '2-.;e. me VOR stations must be located such that the aircraft could complete the flight to a suitable 3 =:-:v:-t and make an instrument approach if the low frequency system fails. The airplane must also =-= ::.!eled to allow for such a failure. In the case of IFR operation over routes in which navigation is based on low-frequency radio
.....-;::e or automatic direction finding, only one low-frequency radio range or ADF receiver need be - s:alled if the airplane is equipped with two VOR receivers, and VOR navigational aids are so :.:a:ed and the airplane is fueled so that, in the case of failure of the low-frequency radio range or .:..:>X: receiver, the flight may proceed safely to a suitable airport by means of VOR aids and :.:::::plete an instrument approach by use of the remaining airplane radio system. Whenever a different VOR station is tuned, the pilot must listen to the Morse code .:::!Jtification. This will ensure that the correct frequency has been tuned and that a usable signal :;:.:: is not reliable enough off or the indent will be changed to the letters T-E-S-T. Other than the .:;:}ti.fier, the station may appear to be broadcasting a normal signal. During periods of routine or emergency maintenance, coded identification (or code and voice, "'·~ere applicable) is removed from certain FAA NAVAIDS. During periods of maintenance, VHF ·very High Frequency) ranges may radiate a periods of maintenance. VHF ranges may radiate a :--E-S-T code. No person may operate an aircraft under IFR using the VOR system of radio navigation unless :::e VOR equipment of that aircraft has been operationally checked within the preceding 30 days. ::1e pilots may check the accuracy of the VORs in one of several ways.
A. The VORs may be checked using a VOT test facility on an airport. The VOT broadcasts the 360 radial and so the CDI (Course Deviation Indicator) needle should center either on a setting of360 with a FROM indication or on 180 with a TO indication. A deviation of 4° is acceptable for a VOT check. B. If a VOT is not available, a VOR checkpoint may be used instead. The aircraft must be moved to the checkpoint and the designated radial set in the CDI course. The acceptable variation for a ground check is 4°. For an airborne check the allowable variation is 6°. C. If no VOT or VOR checkpoint is available, the VORs may be checked against each other. This is called a "dual VOR check". Turn the VORs to the same station and check the difference in indicated bearing. If they are within 4° of each other, the check is satisfactory. And this check can be performed on the ground or in the air.
If a dual system VOR (units independent of each other except for the antenna) is installed in 33
the aircraft., the person checking the equipment may check one system against the other. The maximum permissible variation between the two indicated bearings is 4°. The person making a VOR check must make an entry in the aircraft log or other record. A proper entry includes the date, place and bearing error. The checker must sign the entry. Besides the VOR check, the altimeter system and the transponder must have been checked within the last 24 calendar months. Whenever VOR receivers are required on board an aircraft operating, it must also have at least one DME (Distance Measuring Equipment) receiver on board as well. If the DME fails in flight, the pilot must inform ATC as soon as possible. DME indicates the actual distance from the station to the receiving aircraft in nautical miles. That is different from the horizontal distance because the aircraft is always higher than the DME ground station altitude which is included in the slant range. As a practical matter, the difference between the horizontal distance and the "slant range" is insignificant at distances of more than 10 miles from the station. There is a considerable error close to the station when the aircraft is at high altitudes. In such a situation, almost all of the slant range distance is vertical. When an aircraft passes over a DME station, the distance indicated at station passage is the altitude of the aircraft above the station in nautical miles. For example, if an airplane flew over a VORTAC (Collocated VOR and TACAN navaids) site 12 000 feet above the station, the DME would indicate 2.0 NM. If an aircraft was flying a perfect 10 DME arc to the left in no wind conditions, the RMI bearing would remain on the left wing-tip reference mark indicating that the VOR was exactly 90° to the left of the aircraft's heading. With a left crosswind, the pilot would have to tum the aircraft toward the wind to compensate for the drift to the right. That would place the bearing to the VOR less than 90°, and the bearing pointer would be ahead of the wing-tip reference. No person may operate an airplane in controlled airspace under IFR unless within the preceding 24 calendar months, each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system have been tested and inspected. No person may use an ATC transponder required by regulations unless, within the preceding 24 calendar months it has been tested and inspected.
SECTION F
HORIZONTAL SITUATION INDICATOR
The horizontal situation indicator (HSI) is a combination of two instruments: the heading indicator and the VOR (see Figure 2-2). The aircraft heading displayed on the rotating azimuth card under the upper lubber line in Figure 2-2 is 330°. The course-indicating arrowhead that is shown is set to 300. The tail of the course-indicating arrow indicates the reciprocal, or 120. 34
SeleCted heading marker Course select poinrerv--:--;--;;:i;:--
I
Compass card
--i-1-
----.
Lateral deviation bar
Glide slope pointer
Miniature airplane
Lateral deviation scale Heading select knob
Course select knob To I From pointer
Figure 2-2 Horizontal Situation Indicator (HSI)
The course deviation bar operates with a VORILOC (localizer) navigation receiver to indicate left or right to deviations from the course that is selected with the course-indicating arrow. It ;noves left or right to indicate deviation from the centerline in the same manner that the angular movement of a conventional VORILOC needle indicates deviation from course. The desired course is selected by rotating the course-indicating arrow in relation to the azimuth card by means of the course set knob. This gives the pilot a pictorial presentation. The fixed aircraft symbol and the course deviation bar display the aircraft relative to the selected course as though the pilot was above the aircraft looking down. The TO/FROM indicator is a triangular-shaped pointer. When this indicator points to the head of the course arrow, it indicates that the course selected, and if properly intercepted and flown, will rake the aircraft TO the selected facility, and vice versa The glide slope deviation pointer indicates the relationship of the aircraft to the glide slope. When the pointer is below the center position, the aircraft is above the glide slope and an increased rate of descent is required. To orient where the aircraft is in relation to the facility, first determine which radial is selected look at the arrowhead). Next, determine whether the aircraft is flying to or away from the station 1ook at the TO/FROM indicator) to fmd which hemisphere the aircraft is in. And then determine how far from the selected course the aircraft is (look at the deviation bar) to find which quadrant the 3.ircraft is in. Last, consider the aircraft heading (under the lubber line) to determine the aircraft's ?OSition within the quadrant Aircraft displacement from course is approximately 200 feet per dot per nautical mile. For example, at 30 NM from the station 1-dot deflection indicates approximately 1 NM displacement of tile aircraft from the course centerline. Therefore a 2.5-dot deflection at 60 NM would mean the ilicraft is approximately 5 NM from the course centerline. ~ither
35
Several IDS presentations and the relevant aircraft position and direction of flight are shown by Figure 2-3 and Figure 2-4.
G
H
Figure 2-3 HSI Presentations
1$>
cS> =AIRCRAFT POSrTlON AND DIREC110N OFFUGHT
Figure 2-4 Aircraft Position and Direction of FUgbt
HSI indicator "A" is set up w ith the head of the arrow pointing to 270 (normal sensing). The Course Deviation Indicator (CDI) is centered; therefore, the aircraft is on the extended centerline of runway #9 and #27. With a heading of 360, indicator "A" represents an aircraft at position #6 and#9. HSI indicator ''B" is set up with the head of the arrow pointing to 090 (reverse sensing). The CDI indication is deflected right, which means the aircraft is actually to the south of the extended centerline. Indicator ''B'' then, with the aircraft flying on a heading of090, could be at position #13 and #5. Remember that the local receiver does not know where you are in relationship to the antenna site. HSI indicator "C" is set up with the head of the arrow pointing to 090 (reverse sensing). With the CDI centered the aircraft is on the extended centerline. And with a heading of090 position #12 36
::=:e : ::lly one which would have that indication.
HSI indicator ''D" is set up with the head of the arrow pointing to 090 (reverse sensing). The '-' ...::dication is deflected right, which means the aircraft to the south of course. On a beading of : : ;osition #2 is the only choice. :iSI indicator "E" is set up with the head of the arrow pointing to 090 (reverse sensing).With c.:.= .::>I deflected right, the aircraft is to the south of the extended centerline. On a heading of045, -s:::on #8 or #3 are the only answer.
HSI indicator "F' is set up with the head of the arrow pointing to 090 (reverse sensing). The .:::;: mdication is deflected; tl.erefore, the aircraft is on the extended centerline of runway #9 and =:- With a heading of270 indicator "F" represents an aircraft at position #4. HSI indicator "G" is set up with the bead of the arrow pointing to 270 (reverse sensing).The _:::): indication is deflected left; therefore, the aircraft is right of the extended centerline of runway =- :!-'ld #27. With a heading of270 indicator "G" represents an aircraft at position #7 or #11. HSI indicator "H" is set up with the head of the arrow pointing to 270 (reverse sensing). The ::>I indication is deflected left; therefore, the aircraft is right of the extended centerline of runway :.: ~d #27. With a heading of215 indicator "H" represents an aircraft at position #I. HSI indicator "P' is set up with the head of the arrow pointing to 090 (reverse sensing).The OI indication is deflected left; therefore, the aircraft is right of the extended centerline of runway ::. md #27. With a heading of 270 indicator "P' represents an aircraft at position #7 or # 11.
SECTION G
RADIO MAGNETIC INDICATOR (AMI)
The compass card shows the aircraft heading !: ill times under the lubber line. The two needles ~)W the bearings TO and FROM the number 1 .::.::~ number 2 VCRS. The thin needles can be :;.::ected to display ADF bearing information .The ..Jead of each needle shows the magnetic bearing : 15 TO the station (330 radial) and the number : :::eedle shows 255 10 the station (075 radial). 5.:-e Figure 2-5. To orient where the aircraft is in relation to =e facility, first determine which radial is ;e.ected to find which quadrant you are in (look Figure 2-5 Radio Magnetic Indicator !: :he tail of the needle, if you are tying to orient . c-'JI'Selfrelative to the VOR, make sure you are using the VOR needle). Next, consider the aircraft .:e~ding (under the lubber line) to determine the aircraft's position within the quadrant. 37
The magnetic beading of the aircraft is always directly under the index at the top of the instrument. The bearing pointer displays bearings TO the selected station and the tail displays bearings FROM the station.
SECTION H LONG RANGE NAVIGATION SYSTEMS When an air carrier operates on routes outside of the 48 contiguous states where the aircraft's position cannot be reliably fixed for more than one hour, special fuel applies. The aircraft must either be equipped with a "specialized means of navigation" (inertial navigation system or Doppler Radar). Or one of the flight crewmembers must have a current flight navigator certificate. The FAA may also require either a navigator or the specialized navigation routes which meet the one-hour fuel if they feel it's necessary. All routes that require either the navigator or specialized mean:> of navigation must be listed in the air carrier's operations specifications. Certain routes over the North Atlantic Ocean between North America and Europe require better than normal standards of navigation. Administrator (the FAA) has authority to grant a deviation from the navigation standards if an operator requests one. Inertial Navigation System (lNS) is the primary system used by air carriers for over-water navigation. Prior to flight, the pilots enter the present latitude and longitude of the aircraft and the fixes that make up the desired route. The INS constantly updates its position by signals from self-contained gyros and accelerometers. The unit then computes the direction and distance to the next fix and displays this information on the aircraft's navigational source. If the INS gets input of the aircraft's heading and airspeed, it can compute and display the wind and any drift angle. When INS is used as the navigation system, the aircraft must have either two INS and Doppler Radar units. INS is a totally self-contained navigation system, comprised of gyros, accelerometers, and a navigation computer, which provides aircraft position and navigation information in response to signals resulting from inertial effects on system components, and does not require infom1ation from external references. If a certificate holder elects to use Inertial Navigation System it must be at least a dual system.
At least 2 systems must be operational at take-off. The dual system may consist of either 2 INS units, or 1 INS unit, or 1 INS unit and 1 doppler radar unit. LORAN-Cis a pulsed, hyperbolic system operating in the 90 to 110KHz frequency band. The system is based on measurement of the difference in time of arrival of pulses of RF energy radiated by a "chain" of transmitters located hundreds of miles apart Within a chain, one station is designated as the Master (M) and the others are called secondaries, Whiskey CW), X-ray(X), Yankee (Y) and Zulu (z). Each chain is identified by its unique Group Repetition Interval (GRI). NOTAM (Notice to Airmen) information on the status of any LORAN-C chain or station 38
~:!5 in the United
States can be found in NOTAM (D)S under the identifier ·'LRN''. :be LORAN-C receiver in the aircraft converts the time difference (TD) information into
:'='.:-~phic
coordinates. Using this information, it generates a course and distance to a designated
--·"X'int fix. LORAN-C installation is approved on an individual basis. If a particular aircraft .:;::::"2-.ation is approved for IFR operations, there will be an entry in the airplane's Flight Manual : -:-: .ement or the aircraft will have an FAA Form 337 (major repair or alteration) approving the __s-~ation.
: ORAN-C originally developed as a marine navigational aid has gained wide acceptance in
co= ::: iation community in recent years. The chains were set up in the U.S. coastal areas. Originally ::::.-:::-~ was a gap in suitable coverage in the midwest and southwestern U.S., and this gap has been = :-.: with the commissioning of an additional chain. LORAN is approved for IFR in the 48 .:-::_guous states. During the approach phase, the receiver must detect a lost signal or a signal blink ::::.'110 seconds of the occurrence and warn the pilot of the event. LORAN-e is approved for VFR navigation. It is also approved for IFR navigation, but is ~~~oved on an individual basis. A pilot may determine if a LORAN-e receiver is autl}orized for 2~ :?erations by consulting the Airplane Flight Manual Supplement or an FAA Form 337 (major ~~.:.;,:or alteration), in aircraft maintenance records, or possibly by a placard installed near or on the ax:::ol panel. Pilots must familiarize themselves with the above referenced documents to verify the a•.. _val level of the LORAN-C receiver they are operating.
5 ::CTION I APPROACH SYSTEMS The primary instrument approach system in the United States is the Instrument Landing SyHem (ILS). The system can be divided operationally into three parts: guidance, range and ~..s..::!l
information (approach lights, touchdown and centerline lights, runway lights). If any of the
:: :::.ents is unusable, the approach minimums may be raised or the approach may not be ::... '1orized at all. The guidance information consists of the localizer for horizontal guidance and the glide slope
f.:- \·ertical guidance. The localizer operates on one of 40 frequencies. The localizer transmitter =~-=:-ares on one of 40 lLS channels within the frequency range of 108.10 to 111.95 MHz. The \i::5e code identifier of the localizer is the letter "I" (··)followed by three other letters unique 1: :.:at facility. The portion of the localizer used for the ILS 3J'proach is called the front course. --e ;:>ortion of the localizer extending from the far end of the runway is called the back course. --=back course may be used for missed approach procedures or for a back course approach if one !:! ~ ..:blished. Range information is usually provided by 75 MHz marker beacons or. occasionally, by D?v.tE. --=:e are four types of marker beacons associated with ILS approaches-the outer marker. the ::!e marker, the inner marker and the back course marker. Flying over any marker beacon will
=-
iQ
result in both visual and aural indications. The outer marker is identified by a blue light and continuous dashes in Morse code at a rate of 2 per second. The middle marker is indicated by a flashing amber light and alternating dots and dashes at a rate of 2 per second. The inner marker flashes the white light and sounds continuous dots at 6 per second. The back course marker will also flash the white light and sound a series of 2-dot combinations. See Figure 2-6.
_,.,_..,__
-"""
VHF...,._
·--
lS""""""'da1s"""-'dbe
......~
101 1010 \tiiShtHL. RlcMIM
~-.....-~- 901011150Ht.-doj>tl.. CCUIS020'11or.a"-'
11YJITI)Ilial.o:olt&'-
"'"'"*"~..-. SO'I) p:"'""'"' ..... -
~lscll5012!0' lr:lm-- d ~1lmllfrd
tllitlh tcrilO·t:~lttiiiPfOICh tnd.AMenna is on ct:'Ctdne aM """""Yisundor!o011d eoranca
...--- 11'- ·
WCIIIIIU.rltw
O.Mr\\at'lcer
-IS'PQKlm•tod«-
-1/11111 -oo:hlllrlor,...
ltolgllr -
-·-· JL~;~. \1;{ ...... Potntot ~
~<¥'P"""'
ModllllloM OC ~ 95S
f\ltWIVIMQtlde
-~
~
-~t)'i~.:."!....~- -
-~
~
~·~-~~-~·~- ! ~~~~
... ,_., 25 ....
-l'lDIO~KHr,-
M .... OUiif and «WRrid:le
2.5•
g)
no
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lllr;JJ>
Spot4 li
l
<(XI
1a
vs• r
*SlS
1:10 ;
m
ao
150
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130
160 i 7UI
178
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- _. •75
..,.....,... w ... -.o~.,. It& ~(;oft EbtOlOfbcn:lr Md N .... t..ro ....... et~tht tadclt
eoo
m
849
-loatleOIJI;~ Al-"""'-~romr.
'l'i;l.lrtlmo1
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..
~.GIIIMClN.,,....,..
llidflllglltond-
conlfOI h'IWtt ttO ptCM:Jod. tWtl IAJIOprialofiiCUcliooln:lon
....
Figure 2-6 IDstrwnent Landing System (ILS)
1\vo code and light identifications of marker beacons are as follows: Marker Code Light OM BLUE . > :MM AMBER 1M WHITE BC WHITE Often, an ADF facility (called a compass locator) is associated with an ILS approach. Usually it is located at the outer marker, but occasionally it is co-located with the middle marker. An outer compass locator is identified with the first 2 letters of the localizer identification group. A middle compass locator is identified with the last 2 letters of the localizer. 40
_.!
~-
=.:.:.e marker is out of service, the middle compass locator or PAR (Precision Approach
::::- :-;; substituted. The middle marker being inoperative does not affect minimums during a -m-;::-: : approach. The visual information portion of the ILS consists of approach lights, • • • *" _ ;.::j centerline lights and runway lights. --: . :·:!lizer is very narrow. In fact a full scale deflection (CDI moving from the center to full ~ ,..:. :: :ight) is only about 700 feet at the runway threshold. :.._=:--:::: aircraft will require different rates of descent to stay on glide slope. A good rule of ~ ..; :::at the vertical speed in feet per minute will require a descent rate of about 700 feet per .....__~ :.! : J( 5 = 700).
=-s
--=.Jwest approach minimums that can be used for a normal (Category I) ILS approach are a :F - ··: ·: feet and 1 800 feet RVR. A Category ll ILS approach will have minimums as low as a :.C: : :· : : : feet and a visibility requirement of 1 200 feet RVR. The approach has to be approved for
:.:::!';:::· II minimums. In addition to suitable localizer, glide slope and marker beacons, the light system, High Intensity Runway lights (IDRL), Touchdown Zone Lights (TDZL), -=-= l. Centerline Lights (CL) and Runway Visual Range (RVR), Radar, VAS! and Runway End ~ = ~ L ights (REIL) are not required components of a Category II approach system. :-: ctescend below the DH from a Category II approach, the pilot must be able to see one of the .:__: -=~: the runway threshold, the threshold markings, the threshold lights, the touchdown zone - ::: :vuchdown zone markings, the touchdown zone lights, or the approach light system, except =.:: : ~ilot may not descend below l00 feet above the touchdown zone unless the red terminating -z.."""' :::.he red side row bars are distinctly visible and identifiable. 5Jme airports have Category IliA approaches. This type of approach has a required visibility : ~ .:ttle as 700 feet RVR, and no DH. :be simplified directional facility (SDF) and the localizer-type directional air (LDA) are :=~::ach systems that give a localizer-type indication to the pilot, but with some significant :.=::ences. The LOA is essentially a localizer, but it is not aligned within 3° of the runway as a :-:2iizer must be. The localizer can be any width from 3°to 6°wide. If the LDA is within 30° , :-::-;.ight-in minimums will be published for it; if not, only circling minimums wiU be published. The s:::;: may or may not be aligned with the runway. The main difference between it and a localizer is ~-.:d at either 6° or 12°. The Microwave Landing System (MLS) is envisioned as the eventual replacement for the ~ 5 system. It gives an ILS-like indication of azimuth and glide slope but has several advantages _. ;: the older ILS. See Figure 2-7 below. The MLS provides azimuth, elevation and distance .:~: ::nation to aircraft. In addition, it has expansion capability to include selectable back azimuth ==.: jata transmission. It also has the operational flexibility to include selectable glide slope angles ::..: boundaries to provide obstruction clearance in the tenninal area The usable coverage area is - -~ ~ greater than an ILS. Azimuth coverage includes at least 40° either side of the centerline out to : . '\:vt and up to 20 000 feet altitude. If a back azimuth is installed, it covers similar dimensions out -: - ~"M. The glide slope extends out to similar distances and elevations and can be extended up to !!.I_ • .:_:-:
41
15°. The identifier of the present MLS systems (Interim Standard :VU..S) is the letter M (--) followed by a unique three-letter code. If data transmission is included with the :MLS, it will include MLS status, airport conditions and weather. Coverage Volumes
, ,, ' , I
, f
-40"
''
' 20 NMI
' 'Wh4n lr>Stallad
''
'
''
Me~mum &im-1-~
' ' ,- -
Figure 2-7 MIS Coverage Areas
The front azimuth coverage extends: A. Laterally, at least 40° on either side of the runway; B. In elevation, up to an angle of 15° and to at least 20 000 feet; C. In range, to a distance of at least 20 NM. The back azimuth provides coverage as follows: A. Laterally, at least 40° on either side of the runway; B. In elevation, up to an angle of 15°; C. In range, to a distance of at least 7 NM from the runway stop end. The MLS provides precision navigation guidance for exact alignment and descent of aircraft on approach to a runway. It provides azimuth, elevation, and distance. Standard MLS configuration can be expanded by adding one or more of three following functions or characteristics: back azimuth, auxiliary data transmissions, and larger proportional guidance. The MLS back azimuth transmitter is essentially the same as the approach azimuth transmitter. However, the equipment transmits at a somewhat lower data rate because the guidance accuracy requirements are not as stringent as for the landing approach. A great deal of data can be transmitted over the MLS. This includes MLS status, airport conditions and weather. The MLS has capability which allows curved and segmented approaches, selectable glide path angles, accurate 3-D positioning of the aircraft in space, and the establishment of boundaries to ensure clearance from obstructions in the terminal area 42
s::CTION J GLOBAL POSITIONING SYSTEM :he Global Positioning System (GPS) is a satellite-based radio navigational, positioning, and ::ansfer system. The GPS receiver verifies the integrity (usability) of the signals received form ~-= .";PS constellation through RAIM, to determine if a satellite is providing corrupted information. - ::.:Jut RAIM capability, the pilot has no assurance of the accuracy of the GPS position. TfRAIM ..... -:: available, another type of navigation and approach system must be used, another destination
=--=
- -=~ted, or the trip delayed until RAIM is predicted to be available on arrival. The authorization to _.: GPS to fly instrument approaches is limited to U.S airspace. The use of GPS in any other -:;-ace must be expressly authorized by the FAA Administrator. If a visual descent point (VDP) is published, it will not be included in the sequence of .. ::.-points. Pilots are expected to use normal piloting techniques for beginning the visual descent. :- ; database may not contain all of the transitions or departures from all runways and some GPS -e-:eivers do not contain DPS in the database. The GPS receiver must be set to terminal (±1 NM) : ..rse deviation indicator (COl) sensitivity and the navigation routes contained in the database in -:er to fly published IFR charted departures and DPS. Terminal RAIM should be automatically :-:vided by the receiver. Terminal RAIM for departure may mot be available unless the waypoints .:! part of the active flight plan rather than proceeding direct to the flfSt destination. Overriding an :...:.Jmatically selected sensitivity during an approach will cancel the mode annunciation. The RAIM
== CDI sensitivity will not ramp down, and the pilot should not descend to lviDA, but fly to the
- ssed approach waypoint (MAWP) and execute a missed approach. It is necessary that helicopter procedures be flown at 70 knots or less since helicopter departure :-:-cedures and missed approaches use a 20:1 obstacle clearance surface (OCS), which is double the :: ;;d-wing OCS, and turning areas are based on this speed as well. The GPS operation must be conducted in accordance with the FAA-approved aircraft flight ~'1ual (AFM) or flight manual supplement Flight crewmembers must be thoroughly fan1iliar with :e particular GPS equipment installed in the aircraft, the receiver operation manual, and the AFM _- flight manual supplement. Air carrier and the commercial operators must meet the appropriate ;:Jvisions of their approved operations specifications. The pilot must be thoroughly familiar with the activation procedure for the particular GPS ·t.:eiver installed in the aircraft and must initiate appropriate action after the MAWP. Activating the =:ssed approach prior to the MAWP will cause CDI sensitivity to immediately change to terminal =: )JM) sensitivity and the receiver will continue to navigate to the MAWP. The receiver will not : _Jt action to sequence past the MAWP. Turns should not begin prior to the MAWP. A GPS missed !::;roach requires pilot action to sequence the receiver past the MAWP to the missed approach :.: :tion of the procedure. If the missed approach is not activated, the GPS receiver will display an : .::ension of the inbound final approach course and the ATD will increase from the MAWP until it is - ~.,ually sequenced after crossing the MAWP. 43
Any required alternate airport must have approved instrument approach procedure other than GPS, which is anticipated to be operational and available at the estimated time of arrival and with which the aircraft is equipped to fly. Missed approach routings in which the track is via a course rather than direct to the next waypoint require additional action by the pilot to set the course. Being familiar with all of the inputs required is especially.critical during this phase of flight Properly certified GPS equipment may be used as a supplemental means ofiFR navigation for domestic en route, terminal operations and certain instrument approach procedures (lAPS). This approval permits the use of GPS in a manner that is consistent with current navigation requirements as well as approved air carrier operations specifications. Use of a GPS for IFR requires that the avionics necessary to receive aU of the ground based facilities appropriate for the route to the destination airport and any required alternate airport must be installed and operational.
SECTION K AIRPORT LIGHTING AND MARKING A rotating beacon not only aids in locating an airport at night or in low visibility, but also helps to identify which airport is seen. Civilian airports have a beacon that alternately flashes green and white. A military airport has the same green and white beacon but the white beam is split to give a dual flash of white. A lighted heliport has a green, yellow and white beacon. Figure 2-8 shows the basic marking and lighting for a runway with a non-precision approach. The threshold is marked with 4 stripes on either side of the centerline. 1 000 feet from the threshold, a broad "fiXed distance.. marker is painted on either side ofthe centerline (A). The runway lights are white for the entire length ofthe runway (as are the centerline lights if installed). The threshold Is lit with red lights. A
.
OO
QO
~
--<' ....().
-'
(;(1-,t\',.,.,_.,.-t · · ·>~i•lhli"l 0 \\hlhr
,""
0
~~
-0· ~"\.
-o- -o- -o- -o- -o- ::; ~'-
t>Y"'Ia•w
r)
0
Figure 2-8
0
C.'
-. =· -. - . -=·.
OOOuOvOOfll)
0
0
0
0
0
-
0
0
0
')
()
Basic Marking and Lighting for a Ruoway
Figure 2-9 shows the somewhat more elaborate ICAO marking for a non-precision runway. In addition to the fixed distance marker, there are stripes painted on the runway every 500 feet to a distance of 3 000 feet from the threshold. This runway has either high intensity runway lights (HIRL) or medium intensity runway lights (MIRL) installed. These lights are amber rather than white in the areas within 2 000 feet of the threshold. This gives the pilot a "caution zone" on 44
N u,httnn~ -
Ap;-.t:.xun:ne
r <:toll Httrncun•nr;
A
r.,
r:>
9
o
r:>
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........... .,.,
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B
I (;
. . •
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Figure 2-9 ICAO Marking for a Non-precision Runway ~
;·ze 2-10 shows the lighting and marking for a precision instrument runway. The runway
-:-: - ·~ has been modified to make it easier to fell exactly how much runway remains. The stripes _-: :-__ at 500 feet intervals for the 3 000 feet from the threshold. The HIRL or MIRL turns amber
· ::- = 2 000 feet closest to the threshold. The centerline lighting has alternating red and white =·:: :::om 3 000 feet to 1 000 feet to go, and has all red lights in the 1 000 feet closest to the -.:-: :.::•id. A
..,.,
..,..,.,..,....,
c
8 :)
0
0
-
t
0
' o-nloltll,...,hll
ovn..
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~,
........
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o I o
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o l
-<> ...... -<> ..... -
Cl
Cl
e~
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--=·.. -· =· -.
~ ~-
F
Figure 2-10 The Lighting aod Marking for a Precision Instrument Runway
In addition to the markings discussed above, some runways have distance remaining markers. :-
~se
are simply signs showing the remaining runway in thousands of feet. Taxi leadoff lights
:.::Jciated with runway centerline lights are green and yellow alternating lights, curving from the : -;-:-.!erline of the runway to a point on the exit Some runways have runway end identifier lights
?.Ell..) installed at the threshold. These are synchronized flashing lights (usually strobes) placed .:.:erally at either side of the runway threshold. Their purpose is to facilitate identification of a -.::1way surrounded by numerous other lighting systems. Holding position signs are mandatory instruction signs, and mandatory instruction signs have a :~d background with a
white inscription.
Information signs have a yellow background with a black inscription. They are used to provide :1e pilot with information on such things as areas that cannot be seen from the control tower, ;.pplicable radio frequencies and noise abatement procedures.
Runway holding position signs are located at the holding position signs on taxiways that intersect a runway or on runways that intersect other runways. Holding position markings for ta.'
4n
~ ~vmbinations at each airport of intended
landing.
:... ::::tionally, knowledge about landing performance data permits the pilot to readily determine ::;.: .-\LD for the assigned runway is sufficient for safe LAHSO. lf, for any reason, such as .......::._ _ -:· in discerning the location of a LAHSO intersection, wind conditions, aircraft condition,
c:::::.. :-:~:lot elects to request to land on the full length of the runway, to land on another runway, or ,::e.: ..:..e
LAHSO, the pilot is expected to promptly infonn ATC, ideally even before the clearance
5".:;-.:. :\ LAHSO ~ 1::
e5: -:: ·:
clearance, once accepted, must be adhered to just as any other ATC clearance,
amended clearance is obtained or an emergency occurs. However, a LAHSO clearance preclude a rejected landing. The airport marking, signage and lighting associated with
(;. :..:.S ~ consist of a three-part system of yellow hold-short marking, red and white signage and, in ~
:ases, in-pavement lighting.
~=8TION
L APPROACH LIGHTING
.;:: airplane approaching to land on a runway served by a Visual Approach Slope Indicator - -!..S~ :nust remain on or above the glide slope (except for normal bracketing) until a lower ~-:e
is necessary for a safe landing.
.; \:--\SI gives the pilot a visual glide slope to follow when landing on certain runways. A VAS! ::- :~ ;.vpe is nonnally about 3 (the same as an ILS) and the aim point is about 1 000 feet down the
-..:::-. :i:
5-om the threshold. The angle and aim point of the VASI can be adjusted as necessary to
.!r:- =.=.odate the runway conditions. If a pilot of a high perfonnance airplane is flying a VASI with ~t :-
:e slope steeper than 3S, he/she should be aware that a longer than normal roll-out may result
::::C:. :..-e flare maneuver required by the steep angle. ~.~:.r;y
runways used by air carrier aircraft have a three-bar VASI system to accommodate
_--==-~~ wi!h a high cockpit such as Boeing 747 or DC-1 0. These aircraft need a glide slope that has c. ~ point further down the runway to ensure adequate clearance for the landing gear at the -...:::- :_: :hreshold. The pilot of such an airplane must use the two upwind lights (middle and far bars: :'M;- :
-:=e slope infonnation. :-:-::-ee-bar VASI installations provide two visual glide paths. The lower glide path is provided
_ :.:e ::ear and middle bars and is normally set at 3°, while the upper glide path provided by the - ....>::.: a..:d far bars is normally (114t higher. This higher glide path is intended for use only by high
::.:cc : aircraft to provide a sufficient threshold crossing height •.!.
::-!-color VASI consists of one light projector with three colors: red, green and amber. A
....... _:-- T.dication is amber, an "on glide slope" is green and a "low" is red. A tri-color VASI can be ~
:::: ~distance of 1/2 to 1 mile in daylight and up to 5 miles at night.
--e Precision Approach Path indicator (PAPI) approach light system consists of a row of _ ;:.::5 perpendicular to the runway. Each light can be either red or white depending on the
47
aircraft's position relative to the glide slope. The glide slope indications of a PAPI are as follows: Hlgh Slightly high On glide path Slightly low
4 white lights 1 red, 3 white lights 2 red, 2 white lights 1 white, 3 red lights
Low 4red lights Pulsating visual approach slope indicators normally consist of a single light unit projecting a two-color visual approach path into the final approach area of the runway upon which the indicator is installed. The below glide path indication is normally pulsating red, and the above glide path indication is normally pulsating white. The "on glide path indication" for one type of system is a steady white light, while for another type system, the on glide path indication consists of an alternating red and white.
48
CHAPTER 3 AERODYNAMICS This chapter establishes the basic knowledge elements of aerodynamics. We have 7 parts: lift !::i drag, stability, flight controls, high-lift devices, tum, VMc and high speed flight.
SECTION A LIFT AND DRAG 3ERNOULLI 'S EQUATION Bernoulli's equation is effectively the explanation for how an airplane is able to fly. It is in ;:.ility a special case of the First Law of Thermodynamics. In other words, it states that Energy can ·v~ be created or destroyed. However, fortunately for those of us who like to fly, energy can be :.:·nverted from one form into another, 1 2pfl+P=Po
:ere:
kp'Vl-
Dynamic Pressure;
P- Static Pressure; Po- Total Pressure. Bernoulli's equation is simply a special case of the above equation. In the case of a fluid or gas, ::e potential energy is represented by the static pressure. The Kinetic energy is a function of the =otion of the air, and of course it's mass. It is generally more convenient to use the density of the 1:: as the mass representation. In words, Bernoulli's equation is usually stated "Static pressure plus dynamic pressure is .:onstant" When a gas is accelerated, its pressure decreases (see Figure 3-1). As the wing moves
Figure 3-1
Variation in Velocity and Pressure through a Venture
49
through the air, the air stream is divided, part of it flowing over one surface while the remainder flowing under the other surface. The air flowing over the upper cambered surface flow faster than the air over the opposite surface to reach the trailing edge. Thus the pressure on the upper wing surface is lower than that on the lower surface and lift is produced.
AIRFOILS An airfoil is a surface which provides aerodynamic force when it interacts with a moving stream of air. A wing generates a lifting force only when air is in motion about it. Some of the terms used to describe the wing, and the interaction of the airflow about it, are listed here. Leading edge - The part of airfoil meets the airflow ftrst. Trailing edge - This is the portion of the airfoil where the airflow over the upper surface rejoins the lower surface airflow. Chord line - The chord line is an imaginary straight line drawn through an airfoil from the lading edge to the trailing edge. Camber - The camber of an airfoil is the characteristic curve of its upper and lower surfaces. The upper camber is more pronounced, while the lower camber is comparatively flat. This causes the velocity of the airflow immediately above the wing to be much higher than that below the wing. Relative wind - This is the direction of the airflow with respect to the wing. If a wing moves forward horizontally, the relative wind moves backward horizontally. Relative wind is parallel to and opposite the flight path of the airplane.
ANGLE OF ATTACK Angle of attack must not be confused with an airplane's attitude in relation to the earth's surface, or with "angle of incidence" (the angle at which the wing is attached relative to the longitudinal axis of the airplane). Angle of attack is defined as the angle between the chord line of the wing. and the relative wind. The coefficient of lift is revealed to be the same at a given angle of attack, regardless of the velocity, air density, wing area, etc. Angle of attack has a large effect on the lift generated by a wing. During take-offs, the pilot applies as much thrust as possible to make the airplane roll along launch rail. But just before lifting off, the pilot "rotates" the aircraft. The nose of the airplane rises, increasing the angle of attack and producing the increased lift needed for take-off.
FOUR FORCES There are four forces acting on an airplane all the time in flight: weight, lift, drag and thrust If the airplane does not accelerate, then we know that the four forces add up to zero. Conversely, if the aircraft is accelerated, then the forces are not in balance. Thrust and drag act opposite each other and parallel to the relative wind. 50
- ·::g.•n is a force which acts down. The concept of weight in fact defmes the term "down". So, _ ~::ow what "down" means, then you understand the direction weight acts. Weight always acts ~:y toward the center of the earth, because it is caused by the downward pull of gravity. :..:..~ is a force which acts perpendicular to the relative wind within the plane of symmetry. --=-= 3 :1othing in the definition which requires lift to be opposite to weight. In fact in many cases ..- _ :-•.:•t opposite to weight The air flowing over the upper surface of the wing is deflected further l::i!::::. ::-..;t flowing across the lower surface and therefore is accelerated. Bernoulli's principle states ~ -.e:l a gas is accelerated, its pressure decreases. Thus the pressure on the upper wing surface is :-- :::an that on the lower surface and lift is produced, 1
L =CL·2 pV"·S
-::: : L -Lift;
CL- Coefficient of Lift; S- WingArea A: zero angle of attack, the
+1·0
~ .::e
on the upper surface of -::.= ·.ving is still less than ~=spheric, but the wing is ~ : _.:ing minimum lift. As the -:: :of attack is increased, the lift ~!.Jped by the wing increases :-::·: rrionately. This is true until -::e ~gle of attack exceeds a =:::::a! value, when the air flowing ~:: :he top of the wing breaks up ..::::: 3 rurbulent flow and the wing -..:o...5 (see Figure 3~2).
~·
.a·
-t12"
+18"
+20"
'"oaltlvea
Figure 3~2 Effect of Angle of Attack on CL Angle of attack and indicated ~peed determine the total lift. An increase in either indicated airspeed or angle of attack increases ··::... lift (up to the stalling angle of attack) and a decrease in either decreases total lift. To maintain "..:= same total lift (i.e. maintain level flight), a pilot has to change the angle of attack anytime .:.::cated airspeed is changed. For example, as indicated airspeed is decreased, the angle of attack =..st be increased to compensate for the Joss of lift. The relationship between indicated airspeed and _ ~ :or a given angle of attack involves the law of squares. If the angle of attack does not change, -~~ lift varies with the square of the indicated airspeed. For example, if the airspeed doubles, the _"': will increase by four times.
Indicated airspeed can be thought of as having two elements-the actual speed of the !..-plane through the air (true airspeed) and the density of the air. As altitude increases, air density ::-.:reases. To maintain the same indicated airspeed at altitude, an aircraft must fly at a higher true 51
airspeed. To produce the same amount of lift at altitude, a higher true airspeed is required for a given angle of attack. Drag is a force which acts in the same direction as the relative wind. But it is not necessarily opposite to thrust. The definition is the equivalent of saying that drag is a force in the opposite direction to flight. It is also true that drag is by definition at right angles to lift. A curve comparing total drag to parasite and induced drag reveals an airspeed at which drag is at a minimum value. At higher airspeeds, total drag increases because of increasing parasite drag. At lower airspeeds, induced drag increases which increases the total drag.
L/D RATIO Since the lift stays constant (equal to weight), the low point on the curve is the airspeed that produces the best lift to drag (LID) ratio. This point is referred to as LIDmax (see Figure 3-3). I Induced drag (Wl)
'I /
Drag
Figure 3-3 Effect of Change in Weight on Drag
A change in weight changes the LID curve. The amount of parasite drag is mainly a function of indicated airspeed. The amount of induced drag is a function of angle of attack. When an aircraft's weight is increased, any indicated airspeed will require a higher angle of attack to produce the required lift. This means that induced drag will increase with increases in weight while there will be little change in parasite drag.
STALL We know that we must increase coefficient of lift as we reduce velocity. But we also know that there is a maximum coefficient of lift value for any given airfoil. Thus, we can conclude that there will be a speed below which we can not fly. The definition of stall speed is: The minimum speed at which the aircraft can produce sufficient lift for level fljght. In this case, since we are specifying that we are also flying straight
_ we know that lift must equal weight Thus, we can make a special case definition that ~ =---
a::d level stall speed is the minimum speed at which the wings can produce lift equal to
-:: ;:: :-fthe airplane,
v.
-A
S1a1l-
~-=
I
2W
\j CLmax · P · S
;r - Weight; ::~x- maximum coefficient of lift; _., _air density;
5 -Wmgarea.. :-:-:ere are four factors detennining the stall speed of our airplane: weight. maximum - -::":::ient oflift, wing area, air density. .;. wing will always stall at the same angle of attack. The load factor, weight and density
_::-_ie will cause the stalling true airspeed to vary, but the stall angle of attack will always be the "';\"eight is in the denominator, therefore as weight increases so does the stall speed. We have : - . -;bly already guessed that, but now we can see that the relationship is between the stall speed !::.-:
:he square root of the weight. Thus, if the airplane weighs twice as much the stall speed will
.:: ~:ease
by the square root of two (1.41).
~aximum
coefficient of lift is in the numerator, therefore a higher maximum coefficient of lift
.: result in a lower stall speed. We can see why designers like wings with high max. lift . _~fficients. Wmg area is also in the numerator. Therefore, a larger wing is one of the easiest ways to give .:.:.. airplane a lower stall speed.
Air density is also in the numerator. Therefore, we lmow that the stall speed will increase as :..:e air density decreases. In other words, stall speed will increase as altitude increases.
SECTION 8
STABILITY
Stability refers to how an aircraft responds to changes in angle of attack, slip or bank. Control refers to the ability to initiate and sustain changes in angle of attack, slip or bank. In other words, stability and control are opposites.
An aircraft without sufficient stability will be difficult, even dangerous to fly. On the other hand, if the aircraft is so stable that it cannot be controlled that will also be dangerous.
STATIC STABILITY Static stability refers to the air.craft's initial response when disturbed from a given angle of attack, slip or bank. Positive static stability is an initial tendency to return to its original anirude of
53
equilibrium. When iL continues to diverge, it has ncgath c static SU!'tilit:•. If an aircraft tends to remain in its new disturbed state. it has neutral static stahilit:. \lost airplanes have positive static stability in pitch and ya\\, and arc clu!>c to neutrally ~tab!~ in roll. The ·.erticu.l tail is the primary source of direction stability (yaw). ami the horizontal tail is the: prima;:. source of pitch stability.
DYNAMIC STABIL ITY Dynamic stabil ity refers to the aircrafl. response over time v.hen disn!rbcd from a given nnglc of attack, slip or bank. Wl1en an aircraft is disturbed from equilibrium :..-.a :hen Lries ro return, it will invariably overshoot the original attitude and then pitch back. This rem:lS in a series of oscillations. If the oscillations become weak with time, the aircraft has positiYe dynami.: 5:.a~ilit:·. If the aircraft diverges further away from its original attitude with each oscillation. it has negative dynamic st1bility.
CENTER OF GRAVITY The center of gravity (CG) is by definition the point about which all gra; ltational moments add up to zero. If the CG is toward its rearward limit, the aircraft t-e le~s stable in both roll and pitch. As the CG i~ moved forward, the ~t.'lbility impnw~ s . E\·cm though an airplane \\ill be less stable with a rearward CG. it will have some desirable aerodynamic charam~ri~tics due to reduced aerodynamic loading of horizontal tail surface. This type of an airplane "iU h:m; a slightly lower c;tall speed and will cruise faster for a given power setting.
''ill
GROUND EFFECT When an aircraft flies in ground ciTeel, the ground interferes '' ith :.he tip \ Ol.>!:'\. This reduces the induced drag. If the wing Oev. right at ground level there would be no \One~~: all and thcretore a large reduction in induced drag. I his ground effect reduces induced dra; (and :_t..,ere•o:e total drug) and increases lif\. As an airplane nics out of ground ciTcct on take-off. the increased induced drag will require a higher angle of attack. The ground eflcct falls o1frapidl~ ''ith Jltirude
SECTION C
FLI GHT CONTROLS
lt is very dillicull to move the night control surfaces of jet aircraft with just me\:hanical and aerodynamic forces. Flight controls are usually mo,cd b) hydraulic actuators and divided into primary flight controls and secondary or atL'\iliru: night controls. The most common control arrangement on the conventional airplane is ailerons on th·e main wing for roll control and a horizontal tai l known as the stnbililcr with moveable elevators for pitch control. There is also a vertical fin with u rudder for directional or yaw control. ~econdary (or auxiliary) flight controls 54
include tabs, trailing-edge flaps, leading-edge flaps, spoile~; and slats.
ROLL CONTROL Roll Control is provided by the ailerons and flight spoilets. When the ailerons are deflected the down going aileron increases the camber of one wing. The up-going aileron decreases camber on the other wing. The result is an asymmetric lift betwee.n the wings. This causes the roll rate to increase away from the wing with the greater lift It is important to note that as long as a net moment (lift times distance) exists between the two wings the aircraft will roll faster and faster. The exact mhc of controls is determined by the aircraft's flight regime. In low speed flight all control surfaces op,!rate to provide the desired roll control. When the aircraft moves into higher speed operations, •control surface movement is reduced to provide approximately the same roll response to a given irtput through a wide range of speeds. Many aircraft have two sets of ailerons-inboard and outboard. The inboard ailerons operate in all flight regimes. The outboard ailerons work only when the wing flaps are extended and are automatically locked out when flaps are retracted. This makes good roll response in low speed flight with the flaps extended and prevents excessive roll and w ing bending at high speeds when the flaps :ll'e retracted.
SPOILERS The spoiler will disrupt (separate) the boundary layer, thereby increasing drag and "spoiling" .!ft on the part of the wing affected by the spoiler. If raised on only one wing, they aid roll control :y causing the lift of that wing drop. If the spoilers raise symmetrically in flight, the aircraft can =::her be slowed in level flight or can descend rapidly without an increase in airspeed. When the :?oilers rise on the ground at hlgh speeds, they destroy the wing's lift that puts more of the aircraft's \'eight on its wheels which makes the brakes more effective. Often aircraft have both flight and ground sr,oilers. The flight spoilers are available both in J ght and on the ground. However, the ground spoilers can only be raised when the weight of the l::'craft is on the landing gear. When the spoilers deploy on the ground, they decrease lift and make :.-:~ brakes more effective. In flight, a groun.d-sensing switch on the landing gear prevents : : ?loyment of the ground spoilers .
.QRTEX GENERATORS The vortex generators is designed to stic·k up out of the boundary layer into the free stream. It :::1erates turbulence which re-energizes the boundary layer and prevents flow separation and the .:.endant pressure drag (review drag as required). When located on the upper surface of a wing, the .::ex generators prevent shock-induced s•eparation from the wing as the aircraft approaches its =:!cal Mach number. This increases aileron effectiveness at high speeds.
55
TABS Another way of changing the amount of force the pilot must apply to the control column is through servo and anti-servo tabs. In this system the control column is directly connected to the control surface but a tab is geared to the movement of the control surface .so that it either assists the movement of the control, or counters the movement of the control. Thus, the controls can be made to feel heavier or lighter than they would otherwise. Servo tabs are on the trailing edge of the control surface and are mechanically linked to move opposite the direction of the surface. If the tab moves up, the surface moves down. The use of trimming tabs is one method of relieving aerodynamic load by means of a secondary control surface attached to tht~ end of the primary surface. Trimming tabs must be operated by a control mechanism in the required direction. This may be done manually by cables connected to a control wheel in cockpit, or electrically by servomotors attached to the cable. Trim tabs must be moved in the opposite direction to that of the primary control surface. Anti-servo tabs move in the same direction as the primary control surface (see Figure 3-4). This means that as the control surface deflects, the aerodynamic load is increased by movement of
the anti-servo tab. This helps to prevent the .control surface from moving to a full deflection. It al·;o makes a hydraulically-boosted flight com'rol more aerodynamically effective than it would otherwise be.
NOSE·UP PITCl1
NOSE-DOWN PITCH
Figure 3-4 Anti-servo Tabs Opposes Further Movement and Provides "Feel"
Some jet aircraft have control tabs for use in the event of loss of all hydraulic pressure. Movement of the control wheel moves the control 1t.ab which causes the aerodynamic movement of the control surface. The control tab is used only du•ring manual reversion, that is, with the loss of hydraulic pressure. They work the same as a servo ta1? but only in the manual mode.
SECTION 0
HIGH-LIFT DEVICES
Swept wing jet aircraft are equipped with some hig:h-lift devices including leading edge flaps, slots or slats, and trailing edge flaps. All of the high-lift devices are to increase lift at low airspeeds
56
~ :o
delay stall until a higher angle of attack.
-EADING EDGE DEVICES The two most common types of leading-edge devices are slats and Krueger flaps. The Krueger :":ap extends from the leading edge of the wing, increasing the camber of the wing. The slat also e:\."tends from the wing's leading edge but it creates a gap or slot This slot allows high energy from .:z1der the wing to flow over the top of the wing that delays stall to a higher angle of attack than would otherwise occur. It is common to find Krueger flaps and slats on the same wing.
TRAILING EDGE FLAPS The primary purpose of flaps is to increase the camber of the wing. A flap which increases the wing camber without forming a slot, as described below, is called a plain flap. A flap which moves back opening a slot when extended is called a fowler flap.
SECTION E TURN When an airplane is in a level turn it is in a state of acceleration. However, all the acceleration is confined to a plane parallel to the horizon. Therefore, the vertical component of the lift vector must completely balance the weight vector which is vertical by definition (see Figure 3-5). When the pilot rolls the airplane into a turn, he must increase the total lift of the wing so that the vertical component is equal to the airplane's weight by increasing the angle of attack. If no compensation is made for the loss of vertical component of lift in a turn, the aircraft will sink.
r?·· ····~
L
i w
w
w
30'
70'
Bank Angle
Bank Angle
Figure 3-5 Tile Steeper the Bank, the Greater the Lift Force Required from the Wings
Load factor is the ratio of the weight supported by the wings to the actual weight of the aircraft. On the ground or in unaccelerated flight the load factor is one. Conditions which can increase the load factor are vertical gusts (turbulence) and level turns. In a level turn, the load factor is dependent only on the angle of bank. Airspeed, turn rate or aircraft weight have no effect on load factor. Rate of turn is the number of degrees per second at which the aircraft turns, 57
w=~
v
T=21tL_ g tany
where: w- rate of tum; T- time to tum;
y- angle of bank; V - velocity.
The time to tum is proportional to velocity and inversely proportional to angle of bank. In other words, it takes longer time to tum at a high speed, but less time to turn at a large angle of bank.
R= -
v-
gtany
Radius of turn depends on three variables: g, velocity squared (V"), angle of bank. Notice in the development of the radius of turn equation that the weight (J¥) canceled out of the equation. This is a very important observation since it means that the size of the aircraft has no effect on the radius of tum. Thus, two aircraft flying at the same angle of bank and velocity will make the same radius of tum even if one is 1 000 times larger than the other. Radius of tum depends on velocity squared and is inversely proportional to the tangent of the angle of bank.
SECTION F VMc
P-FACTOR When the aircraft slows down, the angle of attack must increase. When this happens the plane of rotation of the propellers is no longer at right angles to the TAS. As a result the downgoing blade and upgoing blade on the propeller each operate at a different angle of attack. The downgoing blade will be at a greater angle of attack and therefore will produce more thrust (see Figure 3-6). 58
Relabv. Aknow UpgomQ Blade
Figure 3-6
Down Going Prop Blade Produces More Thrust with the Tail on the Ground
CRITICAL ENGINE Because of''P-Factor'' on most propeller-driven airplanes, the loss of one particular engine at high angles of attack would be more detrimental to performance than the loss of the other. One of the engines has its thrust line closer to the aircraft centerline. The loss of this engine would more adversely affect the performance and handling of the aircraft; therefore this is the "critical engine". For unsupercharged engines, VMc decreases as altitude is increased. Stalls should never be practiced with one engine inoperative because of the potential for loss of control. Engine out approaches and landings should be made the same as normal approaches and landings. Banking at least 5° into the good engine ensures that the airplane will be controllable at any speed above the certificated VMc, that the airplane will be in a minimum drag configuration for best climb performance, and that the stall characteristics will not be degraded. Engine out flight with the ball centered is never correct. The blue radial line on the airspeed indicator of a light, twin-engine airplane represent maximum single-engine rate of climb.
SECTION G HIGH SPEED FLIGHT
MACH NUMBER Mach number is the ratio of TAS and the speed of sound. Therefore, if you are traveling at exactly the speed of sound your Mach number is l.O. Mach 8 means your speed is 80 % of the speed of sound, etc. The drag increase largely when the air flows around the rurcraft exceeds the speed of sound (Mach 1.0). Because lift is generated by accelerating air across the upper surface of the wing, local air flow velocities will reach sonic speeds while the aircraft Mach number is still considerably below the speed of sound. With respect to Mach cruise control, flight speeds can be divided into three regimes-subsonic, transonic and supersonic. Subsonic-all flow evei)'Where on the rurcraft is less than the speed of sound. Transonic flow begin at critical Mach number and some but not all the local air flow velocities are Mach 1.0 or above. When all the local Mach numbers surrounding an aerofoil exceeds Mach 1.0, then the flow at that time is considered to be supersonic. In general tenns the subsonic band extends up to about Mach 0.75, the transonic regime between Mach 0.75 and Mach 1.20.
CRITICAL MACH NUMBER A limiting speed for a subsonic transport rurcraft is its critical Mach number (McRir). That is the speed at which air flow over the wing first reaches, but does not exceed, the speed of sound. At
59
MCRlr there may be sonic but no supersonic flow. The less airflow is accelerated across the wing, the higher the critical Mach number (i.e., the maximum flow velocity is closer to the aircraft's Mach number). Two ways of increasing MeRIT in jet transport designs are to give the wing a lower camber and increase wing sweep. A thin airfoil section (lower camber) causes less air flow acceleration. The sweptwing design has the effect of creating a thin airfoil section by inducing a span wise flow, thus increasing the effective chord length.
MACH TUCK As the aircraft moves into supersonic flight, the aerodynamic center and center of pressure, both move back. The nose of the aircraft always tends to pitch nose down as the aircraft transitions from subsonic to supersonic speed. This tendency is called the "Mach Tuck". This tendency is further aggravated in sweptwing aircraft because the center of pressure moves aft as the wing roots shock stall. When an airplane exceeds its critical Mach number, a shock wave forms on the wing surface that can cause a phenomenon known as shock stall. If the wing tips of a sweptwing airplane shock stall first, the wing's center of pressure would move inward and forward causing a pitch up motion. Although a sweptwing design gives an airplane a higher critical Mach number (and therefore a higher maximum cruise speed), it results in some undesirable flight characteristics. One of these is a reduced maximum coefficient of lift. This requires that sweptwing airplanes extensively employ high lift devices, such as slats and slotted flaps, to get acceptably low take-off and landing speeds. Another disadvantage of the sweptwing design is the tendency, at low airspeeds. for the wing tips to stall frrst. This results in loss of aileron control early in the stall: and in very little aerodynamic buffet on the tail surfaces. Dutch roll tendency is typical of sweptwing designs. If such an airplane yaws, the advancing wing is at a higher angle of attack and presents a greater span to the au- stream than the retreating wing. This causes the aircraft to roll in the direction of the initial yaw and simultaneously to reverse its direction ofyaw. When the yaw reverses, the airplane then reverses its direction of roll and yaw again. This roll-yaw coupling is usually damped out by the vertical stabilizer. But at high speeds and in turbulence, this may not be adequate, so most aircraft are also equipped with a yaw damper to help counteract any Dutch roll tendency.
60
CHAPTER 4 PERFORMANCE In the following chapter we will present the conception required to understand the performance of transportation aircrafts. Furthermore, this chapter will concentrate on the methods to calculate the performance of transportation aircrafts. The exams will include both conception test and method test. In the exams, all questions are single-choice test, in which you should ftnd out the only one right choice from three answers. In terms of an aircraft, performance can be defined as a measure of the ability of the aircraft to carry out a specified task. In this chapter the expression "performance" will be taken to refer to tasks relating to the flight path of the aircraft mostly rather than to those involving its stability, control or handling qualities. For a civil transport flight operation, the flight path consists of a number of elements, or maneuvers, which make up the total mission but which can be analyzed separately, these are, take-off, climb, cruise, descent and landing, with additional maneuvers such as turning or flying a holding pattern. Performance can be used as a measure of the capability of the aircraft in many ways. In the case of a civil transport aircraft it determines an element of the cost of the operation of the aircraft and hence it contributes to its economic viability as a transport vehicle. Performance can also be regarded as a measure of safety. Whil.st an aircraft has an excess of thrust over drag it can increase its energy by either climbing or accelerating; if the drag exceeds the thrust then it will be losing energy as it either decelerates or descends. In safe flight, the aircraft must not be committed to a decrease of energy that would endanger it so that, at all critical points in the mission, the thrus1 available must exceed the drag; this is a consideration of the performance aspect of the airworthiness of the aircraft. Airworthiness and performance are intimately associated. However, in any conflict between efficiency and flight safety the airworthiness criterion relating to the safety of the aircraft must be considered to be dominant In this chapter, we wiU mainly consider Part 25 of China Civil Aviation Regulations (CCAR 25) which is almost identical to Part 25 of the AmericaiJ counterpart of Federal Aviation Regulations (FAR 25), both of which relate to large civil transpor1 aircraft.
SECTION A ENGINE PERFORMANCE There are two basic forms of engine used for aircraft propulsion: the power-producing engine, 61
which produces shaft power that is then turned into a propulsive force by a propeller, and the thrust-producing engine, which produces its propulsive force directly by increasing the momentum ofthe airflow through the engine. Obviously, the power-producing engine includes both reciprocating engine and turboprop engine. Meanwhile, the usual form of thrust-producing engine is the turbojet engine, although rockets could be included in this category. The type of engine selected for a particular airplane design depends primarily on the speed range of the aircraft. The reciprocating engine is most efficient for aircraft with cruising speeds below 250 MPH (miles per hour), while the turboprop engine works best in the 250 MPH to 450 MPH range and the turbojet engine is most efficient above 450 MPH. Manifold pressure (MAP) is a measurement of the power output of a reciprocating engine. It is basically the pressure in the engine's air inlet system. In a normally-aspirated (unsupercharged) engine, the MAP will drop as the aircraft climbs to altitude. This severely limits a piston-powered airplane's altitude capability. Most piston-powered airplanes flown by air carriers are turbocharged. On this type of engine, exhaust gas from the engine is used as a power source for a compressor that in tum raises the MAP at any given altitude. The flow of exhaust gas to the turbocharger is controlled by a device called a waste gate. Turbocharging allows an aircraft to fly at much higher altitudes than it would be able to with normally-aspirated engines. The term critical altitude is used to describe the effect of turbocharging on the aircraft's performance. The critical altitude of a turbocharged reciprocating engine is the highest altitude at which a desired manifold pressure can be maintained. The pilots of reciprocating-engine-powered aircraft must be very careful to observe the published limits on manifold pressure and engine RPM. In particular, high RPM and low MAP can produce severe wear, fatigue and damage. Both turboprop engines and turbojet engines are types of gas turbine engines. All gas turbine engines consist of an air inlet section, a compressor section, the combustion section, the turbine section and the exhaust. Air enters the inlet at roughly ambient temperature and pressure. As i1 passes through the compressor the pressure increases and so does the temperature due to the heat o1 compression. Bleed air is tapped off the compressor for such accessories as air conditioning and thermal anti-icing. The section connecting the compressor and the combustion sections is called the diffuser. In the diffuser, the cross sectional area of the engine increases. This allows the air stream from the compressor to slow and its pressure to increase. In fact, the highest pressure in the engine is attainec at this point. Next, the air enters the combustion section where it is mixed with fuel and the mixture i! ignited. Note that there is no need for an ignition system that operates continuously (such as th( spark plugs in a piston engine) because the uninterrupted flow of fuel and air will sustair combustion after an initial "light off''. The combustion of the fuel-air mixture causes a grea
62
increase in volume and because there is higher pressure at the diffuser, the gas exits through the turbine section. The temperature of the gas rises rapidly as it passes from the front to the rear of the combustion section. It reaches its highest point in the engine at the turbine inlet. This turbine inlet temperature (TIT) is usually the limiting factor in the engine operation. In many engines, TIT is measured indirectly as exhaust gas temperature (EGT). The maximum turbine inlet temperature is a major limitation on turbojet performance, and without cooling, it could easily reach up to 4 000 op, far beyond the limits of the materials used in the turbine section. To keep the temperature down to an acceptable 1 100 "F to 1 500 "F, surplus cooling air from the compressor is mixed aft of the burners. The purpose of the turbine (s) is to drive the compressor (s) and they are connected by a drive shaft. Since the turbines take energy from the gas, both the temperature and pressure drop. The gases exit the turbine section at very high velocity into the tailpipe. The tailpipe is shaped so that the gas is accelerated even more, reaching maximum velocity as it exits into the atmosphere (see Figure 4-1 below).
o:s..
I F>J""I•' t aJ
He,..,.
Figure 4-1 Turbojet Engine
Combinations of slow airspeed and high engine RPM can cause a phenomenon in turbine engines called compressor stall. This occurs when the angle of attack of the engine's compressor blades becomes excessive and they stall. If a transient stall condition exists, the pilot will hear an intermittent "bang" as backfires and flow reversals in the compressor take place. If the transient condition develops into a steady state stall, the pilot will hear a loud roar and experience severe engine vibrations. The steady state compressor stall has the most potential for severe engine damage, which can occur literally within seconds of the onset ofthe stall. If a compressor stall occurs in flight, the pilot should reduce fuel flow, reduce the aircraft's angle of attack and increase airspeed. That means, recovery must be accomplished quickly by reducing throttle setting, lowering the airplane angle of attack, and increasing airspeed. The turboprop is a turbine engine that drives a conventional propeller. It can develop much more power per pound than can a piston engine and is more fuel efficient than the turbojet engine. Compared to a turbojet engine, it is limited to slower speeds and lower altitudes (25 000 feet to the tropopause). The term equivalent shaft horsepower (ESHP) is used to describe the total engine 63
output This term combines its output in shaft horsepower (used to drive the propeller) and the jet thrust it develops. As the density altitude is increased, engine performance will decrease. When the air becomes less dense, there is not as much oxygen available for combustion and the potential thrust output is decreased accordingly. Density altitude is increased by increasing the pressure altitude or by increasing the ambient temperature. Relative humidity will also affect engine performance. Reciprocating engines in particular will experience a significant loss of brake horsepower (BHP). Turbine engines are not affected as much by high humidity and will experience very little loss of thrust.
SECTION 8
TAKE-OFF PERFORMANCE
All conventional aircraft flights start at the point of departure with a take-off. In this phase, the aircraft is transferred from its stationary, ground-borne, state into a safe airborne state. Since the maneuver takes place in close proximity to the ground, and at low airspeed, there is relatively high risk to the safety of the aircraft. The maneuver must be carried out in a manner that will reduce the risk of an incident occurring to an acceptably low level of probability. In the conventional take-off maneuver, the aircraft is accelerated along the runway until it reaches a speed at which it can generate sufficient aerodynamic lift to overcome its weight It can then lift off the runway and start its climb. During the take-off, consideration is given to the need to ensure that the aircraft can be controlled safely and the distances required for the maneuvers do not exceed those available. In this section, we will discuss take-off performance terminology, which mainly includes the definitions of some distances and airspeeds, and the methods to calculate "V'' speeds and take-off power.
TAKE-OFF PERFORMANCE TERMINOLOGY The space available for take-off is limited by the dimensions of the runway and the area beyond the runway in the take-off direction. The runway is defined as a rectangular area of ground suitably prepared for an aircraft to take off or land. At the end of the runway, there may be a stopway or clearway.
Clearway- a plane beyond the end of a runway which does not contain obstructions and can be considered when calculating take-off performance of turbine-powered transport category airplanes. The first segment of the take-off of a turbine-powered airplane is considered complete when it reaches a height of 35 feet above the runway and has achieved V2 speed (take-off safety speed). Clearway may be used for the climb to "35 feet (see Figure 4-2). For turbine-powered airplanes, a clearway is an area beyond the end of the runway, centrally
64
located about the extended centerline and under the control of the airport authorities. Clearway distance may be used in the calculation of take-off distance. Stopway -an area designated for use in decelerating an aborted take-off. It cannot be used as a part of the take-off distance but can be considered as part of the accelerate-stop distance (see Figure 4-2 below).
Figure 4-l Take-off Runway Definitions
A stopway is an area beyond the take-off runway, not any less wide than the runway, centered upon the extended centerline of the runway, and able to support the airplane during an aborted take-off. Regulation requires that a transport category airplane's take-off weight be such that, if at any time during the take-off run the critical engine fails, the airplane can either be stopped on the runway and stopway remaining, or that it can safely continue the take-off. This means that a maximum take-off weight must be computed for each take-off. Factors that determine the maximum take-off weight for an airplane include runway length, wind, flap position, runway braking action, pressure altitude and temperature. In addition to the runway-limited take-off weight, each take-off requires a computation of a climb-limited take-off weight that will guarantee acceptable climb performance after take-off with an engine inoperative. The climb-limited take-off weight is determined by flap position, pressure altitude and temperature. When the runway-limited and climb-limited take-off weights are determined, they are compared to the maximum structural take-off weight. The lowest of the three weights is the limit that must be observed for the take-off. If the airplane's actt;al weight is at or below the lowest of the three limits, adequate take-off performance is ensured. If the actual weight is above any of the limits a take-off cannot be made until the weight is reduced or one or more limiting factors (runway, flap setting, etc.) is changed to raise the limiting weight After the maximum take-off weight is computed and it is determined that the airplane's actual weight is within the limits, then V1 (take-off decision speed), VR (rotation speed) and V2 are computed. These take-off speed limits are contained in performance charts and tables of the airplane flight manual, and are observed on the captain's airspeed indicator. By definition they Figure 4-3 Take-off Speeds are indicated airspeeds (see Figure 4-3). When the aircraft starts the take-off at rest on the runway, take-off thrust is set and the brakes 65
released. The excess thrust accelerates the aircraft along the runway and, initially, the directional control needed to maintain heading along the runway would be provided by the nose-wheel steering This is because the rudder cannot provide sufficient aerodynamic yawing moment to give directional control at very low airspeeds. As the airspeed increases the rudder will gain effectiveness and will take over directional control from the nose-wheel steering. However, should an engine fail during the take-off run the yawing moment produced by the asymmetric loss of thrust will have to be opposed by a yawing moment produced by the rudder. There will be an airspeed below which the rudder will not be capable of producing a yawing moment large enough to provide directional control without assistance from either brakes or nose-wheel steering or a reducing in thrust on another engine. This airspeed is known as the Min.imum Control Speed, Ground, VMcG· If an engine failure occurs before this airspeed is reached, the take-off run must be abandoned. During the ground run the nose wheel of the aircraft is held on the runway to keep the pitch attitude, and hence the angle of attack in the ground run, ag, is low. This will keep the lift produced by the wing to a small value so that the lift-dependent drag is minimized and the excess thrust available for acceleration is maximized. As the aircraft continues to accelerate, it will approach the lift-off speed, Vwy, at which it can generate enough lift to become airborne. Just before the lift-off speed is reached, the aircraft is rotated into a nose-up attitude equal to the lift-off angle of attack. The rotation speed, VR.. must allow time for the aircraft to rotate into the lift-off attitude before the lift-off airspeed and becomes airborne; this is the end of the ground run distance, S0 . The lift-off speed must allow a sufficient margin over the stalling speed to avoid an inadvertent stall, and a consequent loss of height This may be caused by turbulence in the atmosphere or any loss of airspeed during the maneuvering of the aircraft after the lift-off. The lift-off speed will usually be taken to be not less than 1.2 Vs 1, where Vs 1 is the stalling speed of the aircraft in the take-off configuration. This will give a lift coefficient at lift-off of about 0.7 Ctmax and provide an adequate margin of safety over the stall. If the aircraft is over-rotated to a greater angle of attack at the rotation speed then lift-off can occur too soon and the aircraft start the climb at too low an airspeed. This can occur if, for example, the elevator trim control is set incorrectly or turbulence produces an unexpected nose-up pitching moment. The minimum speed at which the aircraft can become airborne is known as the minimum unstuck speed, VMu· It occurs when extreme overrotation pitches the aircraft up to the geometry limited angle of attack with the tail of the aircraft in contact with the runway. Tests are usually required to measure the take-off performance in this condition. During the take-off run, should an engine fail between the minimum control speed (ground) and the rotation speed, the decision either to abandon or continue the take-off will have to be made. This decision is based on the distances required either to stop the aircraft or to continue to accelerate to the lift-off speed with one engine inoperative. There will be a point during the acceleration along the runway at which the distances required by the two options are equal. This point is recognized by the indicated speed of the aircraft and is known as the take-otT decision speed, V1• The decision speed also determines the minimum safe length of runway from which the aircraft can take off. If an engine fails before the decision speed is reached then the take-off is 66
abandoned, otherwise the take--off must be continued. Once the lift-off has been achieved the aircraft must be accelerated to the tak&-e>ff safety speed (V1). This is the airspeed at which both a safe climb gradient and directional control can be achieved in the case of an engine failure in the airborne state; this phase of the take-off path is known as the transition. The ability to maintain directional control in the climb is determined by the
Minimum Control Speed, Airborne, VMcA· The minimum control speed, airborne, will be greater than the minimum control speed, ground, VMcG, since the aircraft is not restrained in roll by the contact between the landing gear and the runway. In the event of an engine failure in the climb, the aircraft will depart in yaw, which will cause the aircraft to roll and enter a spiral dive if the yaw cannot be controlled. The take-off is complete when the Lowest part of the aircraft clears a screen height of 35ft above the extended take-off surface. The distance between the lift-off point and the point at which the screen height is cleared is known as the airborne distance, SA. The total take-off distance required will be the sum of the ground run distance, So, and the airborne distance, SA. To ensure that the take-off is performed safely, the take-off distances will be suitably factored to allow for statistical variation in the take-off performance of the individual aircraft and in the ambient conditions.
V1 (tak&-e>ff decision speed) is the speed during the take-off at which the airplane can experience a failure of the critical engine and the pilot can abort the take-off and come to a full safe stop on the runway and stopway remaining, or the pilot can continue the take-off safely. If an engine fails at a speed less than Vh the pilot must abort; if the failure occurs at a speed above VI> the pilot must continue the take-off. The take-off decision speed, VI> is the calibrated airspeed on the ground at which, as a result of engine failure or other reasons, the pilot is assumed to have made a decision to continue or discontinue the take-off. V1 is also the speed at which the airplane can be rotated for take-off and shown to be adequate to safely continue the take-off, using normal piloting skill, when the critical engine is suddenly made inoperative. VEF is the calibrated airspeed at which the critical engine is assumed to fail. VEF must be selected by the applicant but must not be less than 1.05 VMc or, at the option of the applicant, not less than VMcG· It is important to know that the critical engine failure speed is an obsolete term for V1 which is now called take-off decision speed. Va (rotation speed) is the lAS at which the aircraft is rotated to its take-off attitude with or without an engine failure. VR is at or just above V1• V1 (tak&-e>ff safety speed) ensures that the airplane can maintain an acceptable climb gradient with the critical engine inoperative.
VMv (minimum unstick speed) is the minimum speed at which the airplane may be flown off the runway without a tail strike. This speed is determined by manufacturer's tests and establishes minimum V1 and VR speeds. The flight crew does not normally compute the VMU speed separately. (see Figure 4-3).
V 1 is computed using the actual airplane gross weight, flap setting. pressure altitude and 67
temperature. Raising the pressure altitude, temperature or gross weight will all increase the computed V1 speed. Lowering any of those variables will lower the V1 speed. A wind will change the take-off distance. A headwind will decrease it and a tailwind will increase it While a headwind or tailwind component does affect the runway limited take-off weight, it usually has no direct effect on the computed V1 speed. The performance tables for a few airplanes include a small correction to V1 for very strong winds. For those airplanes, a headwind will increase V1 and a tailwind will decrease it A headwind, in effect, gives an airplane part of its airspeed prior to starting the take-off roll. This allows the airplane to reach its take-off speed after a shorter take-off roll than in no wind conditions. High rotation speeds and lower air density (high density altitude) both have the effect of increasing the take-off distance. A runway slope has the same effect on take-off performance as a wind. A runway that slopes uphill will increase the take-off distance for an airplane and a downslope will decrease it. A significant slope may require an adjustment in the V1 speed. An upslope will require an increase in V1 and a downslope will require a decrease. An uphill runway will have the effect of decreasing an airplane's rate of acceleration during the take-off roll thus causing it to reach its take-off speeds (V1 and VR) further down the runway than would otherwise be the case. An uphill runway will also necessitate an increased V1 speed in some airplanes.
If there is slush on the runway or if the antiskid system is inoperative, the stopping
performance of the airplane is degraded. This requires that any aborted take-off be started at a lower speed and with more runway and stopway remaining. This means that both the runway-limited weight and the V1 used for take-off be lower than normal.
CALCULATING "V" SPEEDS Although the method to calculate Boeing 737 "V'' speeds (including V1, VR and V2) is similar to Airbus 320 to some extent, it is still necessary to discuss the two methods respectively. Boeing 737 "V" Speeds
The table in Figure 4-4 is used in several problems to determine the pressure altitude from the indicated altitude and the local altimeter setting. The table uses the local altimeter setting to indicate the proper correction to field elevation. For example, assume the local altimeter setting is 29.36" Hg. Enter the table in the left-hand column labeled "QNH lN. HG", and then find the range of altimeter settings that contains 2936" Hg. Read the correction to elevation in the center column. In this case, add 500 feet to the field elevation to determine the pressure altitude. If the altimeter setting is given in millibars, enter the table in the right-hand column. Using operating conditions R-1 (see Figure 4-5), follow the steps for determining the "V'' speeds (see Figure 4-6). Enter the table at the top left in the row appropriate for the pressure altitude and go across until in a column containing a temperature range which includes the given value. In
68
r
ALTIME'"" • .;-; ....
I
STATiot~
J
TO PRESSURE
QFE
STATION
PRESSURE ONH tO PRESSURE! ALTITUDE
fo18S 1000 FT
700
CORRECTION TO eLEVATION
10 ONH IN. HG.
PRESS. ALT
FT
- 28.8- 1 8
28.91
- 29.02 7
29.12 29.23
800 8
29.34
-
29..<4
160
5
t 29.55 29.66
4
29.76 29.87 29.97
900
3
- 30 08 30.19
2
-
ONH MILLIBARS
FOR
9 7fi()
-
-----
30.30 30.41
30.52
- 30.63
to
28.91
!O
29.0.2
to
2912
to
29.23
!0
to
-
10
to
29.34
·
29.44 29.55
to
29.87
:l0.08 30.19
IO
:10.30
to
30.41
---
30.52
to
30.63
to
30.74
30.74 to
30.85 to
L 3096
to
700
986
t 99o
600
30.85 3o.gs 31.07
EXAMPLE
to
.
I 997
400
I
1001
99~1
to
994
10
!)91
to
1001
to
1004
to
1008
200
1004
100
1008 -·-
to
0
'012
·100
1015
-200
1019
-300
1022
-400
10?6
-500
-
·-
-. ··1o3o
--600 --
1034
·700
1037
-80 0
t041
-900
1045
·1000
1048
--983 -986-
to
--
994
500
29.97
to
to
963
29.66 29.76
to
to
800
300
to
10
- - --to 979 I - ·-- ·---··-· 979 ----·-' ~DO
---...--=1000 976
to
to
I .
1012 --· 1015
- 1019 1022 ---to 1026 to
to
1030
to
1034
10
1037-
to
10-11
to
1045
to
1().1...!....J
10
105J
-
ELEVAf10N • 2500 F1'
O"lli • 20 49 '"' 1-10
.COO Ff PRESS Al T • 2900 FT
COilRECTIOt~-
Figure 44 Altimeter Setting to Pressare Altitude
69
OPERATING CONDITIONS
R-1
R-2
R-3
R-4
R-5
FIELD ELEVATION
100
4,000
950
2,000
50
AlTIMETER SETTING
29.50"
1032mb
29.40''
1017mb
~0 . 15"
TEMPERATURE (OAT)
+50 ~F
-15 oc
+59 ~F
O"G
WEIGHT (X1000)
90
110
100
85
95
FLAP POSITION
15°
so
so
14
1"
5HW
STW
20HW
10TW
7HW
RUNWAYSLOPE%
1%UP
1%0N
1%UP
2%0N
15%UP
AIR CONDITIONING
ON
ON
OFF
ON
OFF
OFF
ON
OFF
ON
OFF
635.7
643.8
665.2
657 2
638.4
WIND COMPONENT (KTS)
ENGINE ANTI-ICE CG STATION
~ 95
UF
LEMAC STA 625.0, MAC 134.0 Figure 4-5 B737 TaktH>ff Operating Conditions
this case, enter in the row labeled -I to I (pressure altitude= 500 feet, refer to Figure 4-4) and go to the first column which contains the temperature of +50 "F (be sure to use the Fahrenheit or Centigrade ranges as appropriate). Go down the first column until ui the row appropriate for a flap setting of I 5° and a gross weight of90 000 pounds. The V1 speed is 120 knots, the VR speed is 121 knots and the V2 speed is 128 knots. There are two possible adjustments to make to the V1 speed only. They are noted at the bottom of the table. According to the notes, V1 should be added I knot because of 1% up slope of the runway. That means V1 is 121 knots. Refer to Figures 4-4, 4-5 and 4-6, using operating conditions R-2. See Figure 4-6, enter in the row labeled 3 to 5 (pressure altitude = 3 500 feet, refer to Figure 4-4) and go to the first column which contains the temperature of -15 ·c (be sure to use the Fahrenheit or Centigrade ranges as appropriate). Go down the first column until in the row appropriate for a flap setting of 5° and a gross weight of 110 000 pounds. The V1 speed is 144 knots, the VR speed is 146 knots and the V2 speed is 150 knots. There are two possible adjustments to make to the V1 speed only. They are noted at the bottom of the table. According to the notes, V1 should be subtracted 2 knots because of 1o/c down slope of the runway and 5 knots of tailwind. That means V 1 is 142 knots. In Figure 4-5, other operating conditions including R-3, R-4 and R-5 can be solved by the
similar steps. 70
TAKE-QFF EPR OAT [F~ ..;~ -4-' .:;•1·zt1 :,31 ~ l s!
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Figure 4-6 8737 Tak~ffPerformance
71
Airbus 320 "V'' Speeds In many cases, the aircraft takes off at a weight lower than the maximum permissible weight In consequence, it is possible to continue to comply with limitations regulations (runway. txt segment. obstacle) with a decreased thrust adapted to the weight: this is called Flexible Take-oft and the thrust is called Flexible Thrust. Flexible take-off can be used when the actual take-off weight is lower than the maximum permissible take-off weight for the actual temperature. As this weight decreases when temperature increases, it is possible to assume a temperature at which actual take-off weight would be the limiting one. This temperature is called Flexible Temperature or assumed temperature. The Regular Take-off and Landing Weight (RTOLW) charts (see Figure 4-7) enable the crew to determine for the corresponding runway:
l .!~or~~~~
TAKE-OFF
2.02.30
RTOLW CHARTS
REV 11
LFBO TOULOUSE-8LAGNAC
A320· ..••tAAJ ...••••••
DRY RUNWAY TREF• 29/TMAX- 49 GRAD1~"150/GRAO'l= 600 Wt:;II.>HI • -1 0 -5 0 1000LB ~ 15 44 4-4 44 29 .1 .0 .6 156-156-156 156-156-156 156-156-155 4-4 9 4-4 28 31 4-4 .1 .1 .6 153-153-153 153-153·153 155-155-155 29 4-4 29 4-4 35 4-4 .5 3.9 .6 148-149-149 153-153-153 154-154-154 4-4 34 37 4-4 39 4-"1 .5 .2 .6 149-149-149 151·151-151 154-154-154 38 4-4 41 4-4 43 4-4 .7 .2 .4 148-148-,48 150-150-150 154-154-154 42 44 4-4 4-4 47 4·4 .8 1.1 .1 148-148-148 150-150-150 153-153-153 4-4 45 48 4-4 4-4 50 .e .7 .8 146·146-146 148-149-1 49 151-151-151 50 4-4 52 4-4 4-4 64 .3 .4 .s 148-146-148 148-148-148 149-149-149 !:>4 4-4 56 4-4 58 4-4 .:! .2 •1 145-145-145 146-146-145 147·147-147 58 4·4 59 4-4 4-4 GO .0 1.0 1.9 144-144-144 145-145-145 145-145-145 4-4 60 60 4-4 60 2.0 4.0 0 143-143-143 144-144-144 133-133-133 60 50 so .0 .0 .0 130-131-131 130-131-131 13C-131-i31 60 80 60 .0 .0 .0 12~12&-1:09 129-129-129 12~-129-129 80 60 so .c .0 .0 126-127-177 126·127·127 126-127-127
162.0 160.0 156.0
152.0 148.0 144.0
140.0
136.0
132.0 128.0
124.0
I
120.0 118.0 114.0
Figure 4-7
72
.... ......
RWY 15L JARA 20{02/S'i
I SEQ 002
ELEV. 489.FT CONF. TORA 9840.FT 1+F ASDA 9840.FT FWnc:c TOOA 10170.FT SLOPE .08 •;. TGA
10 31 4-"1 .2 156-156-156 4-4 33 .2 156-156-156 37 4-4
.2 156-156-155 41 4-4 .0 156-156-155 44 4-4 .!l 155-155-155 4-4 48 .4 153-153-153 4-4 51 1.1 151·151-151 55 4-4 .7 149-149-149 69 4-4 .2 147-147-147 4-4 60 3.1 146-146-146
60 .0 133-133-133 60 .0 130-131-131 50 .0 129· 129·129
6C
.o
126-127-127
Ta~ffRTOLW Charts
p 10
2
20 32
s 4-4
37
.8 168-158-158 34 4-4 .8 158-158-158 4-4 38 .7 158-158·158 4-4 42
.s
36 36 37 4i 4C 45
43
157-167·157 45 4-4
48
155-155-155 4-4 49
49
.,
46
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49 49
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119 49
.8 149-149-149 4-4 eo
49
49
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60 .0
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49
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0 133-133-133 60 .0 130-131·131
sc .0 1:HI·129-129 60 .0 128-127·127
49
49 45
49 ~9
49 (!;
A. The maximum permissible take-off weight for the ambient pressure, temperature and surface wind conditions, or B. For a given aircraft weight, the maximum temperature at which a take-off would be permitted. This temperature (corrected for QNH and airbleeds) is called the flexible temperature. A specific chart is established for each runway. It is based on standard atmospheric pressure and takes account of the s~gnificant obstacles along the specified flight path. The configuration is indicated on top of the chart (see Figure 4-7) in the right comer. The weight corresponding to any box is the sum of entry weight and weight increment. It is the maximum permissible T/0 weight corresponding to the temperature shown in the box. The temperature shown in the box is the maximum temperature at which the maximum weight determined as above can be lifted. The limitation indicates the nature of the limitation or the balance between two limitations as resulting from the optimization. Limitation codes are as follows: A. Maximum structural weight; B. Second segment or first segment; C. Runway; D. Obstacle; E. Tire speed; F. Brake energy; G Take-off distance 2 engines operative; H. Final take-off.
In order to get the most out of the chart, there are two kinds of corrections: either on weight when determining maximum take-off weight or on maximum temperature when determining the flexible or limiting temperature. Any QNH variation from the standard, for which the chart is calculated, will affect either the maximum temperature or the weight. The air bleeds will affect the maximum temperature or the weight in the same manner. The effect of QNH variations or bleed consists of an addition or subtraction to the weight as specified on each chart.
Correction on Weight In order to avoid a loss in weight when the actual temperature does not appear in the chart, the weight gradients (Grad) on both sides of the flat rating temperature are given on top of the chart (Grad 1/Grad 2). Flat rating temperature is given, named Tref. Using the data, weight and temperature, given in the upper box of the column selected according to the wind, add the weight determined by multiplying the weight gradient by the difference of temperature between actual temperature and that given in the box. When these two temperatures (actual and maximum) are on each side of flat rating temperature, two steps are necessary. First multiply the weight gradient given above Tref by the
73
difference between maximum temperature and flat rating temperature. Then multiply the weight gradient given below Tref by the difference between flat rating temperature and actual temperature. Add these two values to the maximum weight of the first box. Note: Weight gradients must only be used to extrapolate above the maximum weight shown in the RTOLW chart (upper box of chart). They do not allow to interpolate between two boxes, neither between filled boxes, nor between one filled and one blank box. From this maximum weight, subtract or add the weight increment equivalent to the QNH variation from standard as indicated on the chart. Subtract bleed effect if any. The final weight is the maximum permissible TOW for the actual environmental conditions.
Corrections on Temperature QNH variations and bleeds affect the maximum temperature corresponding to a given weight. The resulting temperature called flexible temperature must be checked as shown on the chart in order to avoid: either a take-off at a higher weight than allowed by the maximum available level of thrust when the flexible temperature is lower than Tref or actual temperature, or setting a thrust derated by more than allowed, maximum derated thrust, i. g., maximum thrust at ISA + 46 "C for the actual conditions.
This maximum derating corresponds to a maximum flexible temperature of lSA +46 ·c. This fmal temperature called corrected temperature (CT) will be entered in the FMGS's MCDU. Any temperature below Tref should not be set. The maximum value of CT which may be set is ISA+46 ·c. Example
Refer to Figure 4-7 and Figure 4-8, find out the maximum take-off weight, the flexible temperature, and corresponding Vt. VR> V2 according to the conditions below. 1) Determination of maximum take-offweight.
DATA: OAT= 10°; QNH = 1 013 mb; 20 kt head wind; Air conditioning OFF; forward C.G. A. Enter in 20 kt head wind column and read temperature and weight: in first line at 32° 162 800 lb B. Use weight gradients for increase in weight capability: between 32° and TREF = 29°
2
between 32° and 10°
19 x 150
Total weight (Maximum capability)
x
600
1 200 lb 2 850 lb
166 850 lb
Maximum permissible take-off weight: for example 162 000 lb (depending on version) C. Read take-off parameters in 162 line for 20 kt bead wind config 1 + F: 74
VI= 158 kt VR= 158 kt
limitation: obstacle
V2=158kt 2) Determination of flexible temperature. DATA: OAT = 15°; Take-off weight: 144 000 lb; QNH= 1013mb; No wind; Air conditioning OFF; forwardC.G A. Enter with 144 000 lb and no wind and read temperature:
47 'C
B. Check the temperature that is lower than maximum flexible temperature: Flex temperature to be enter the FMGS's MCDU
47
·c
C. Read take-off parameters in 144 000 lb line for no wind:
Vi= 153 kt VR= 153 kt
v2 = 153 kt ~A3~0 orr .....
, ..KJttt Qrt'W
tnt~.; MNct.~AL.
\
TAKE..OFF
2.02.30
RTOLW CHARTS
REV 13
p9
ISEQ 032
EFFECT Of O.NH AND I OR BLEEDS
I
!
to :oh ~r.to at<41lm ON'i de...,~on ondtor bltt
... CORRECTIJII$ 01. T!MPfHTU~f If flEX T.t.~E Off P!R~ORMEO
.I
..
I
toRR£CTlONS ON W!!GHT I' TAXE·Gfl WITH FUll THRUST PfRfORM£0
1't /10m~
ONH above 1013 ml>
~"" 40 lb/lnb'
Sub Z"C/ lO onb
ONH balcw 1013 mo
Sui>
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Engi1o A/ ICE 011
Sib ~0 I>
Totol A/1C! ON
Sub 2300 1>
A
~ub
2"C
Sub 5'C
Af condb>nilQ ON
2~0
SUI>
b/mb
56~C
b
~ COMPARE COI\R!CTfD TH•P. !CT\. fl/.7 RATlHG TfMP. (T Rffl AND CAl
CT H~ than OAT } 1M hkt Cl a W.. CT HiQb!! :hto T REI
~ 80lt.,~>obon} ~IM51td
r...D. billed~ ISA + 46'C
No kxblo
IAu<>n poul>lc
Dt'-rmno MAX TOW
• When eirport pressure altitude becomes negative : - ~ geometrical eltnude is negative or equal to 0 : subtract 30 lblmb - if geo:netrical eltitude is positive : add 40 lb/mb down to 0 h pressure altJwde, then subtract 30 lo per additionoi mb.
Figure 4-8 Effect of QNH and/or Bleeds
75
CALCULATING TAKE-OFF POWER Engine Pressure Ratio (EPR) is the thrust indication used on many turbojet aircraft. Basically it is the ratio of the engine exhaust pressure to the intake pressure. For example, if the exhaust pressure is exactly twice the intake pressure, the EPR is 2.00. The EPR setting for maximum take-off thrust will vary with altitude and temperature. In addition, reductions in EPR have to be made when bleed air from the compressor section is used for air conditioning, engine anti-ice and internal regulation of the engine. Boeing 737 Take-off EPR
The table at the top of Figure 4-6 is used to determine take-off EPR. Enter the table with temperature and pressure altitude. To determine pressure altitude, use Figure 4-4. In the table of Figure 4-6, two EPR values are found: one for temperature and one for altitude (be sure to use the table in Figure 4-4 to determine the pressure altitude). The lower of the two is the take-off EPR. For example, if the temperature is 50°F at a pressure altitude of 500 feet, the temperature-limited EPR is 2.04 and the altitude-limited EPR is 2.035. Since there is no listing for this altitude in the table in Figure 4-6, it is necessary to interpolate. At sea level, the altitude-limited EPR is 2.0 l. At 1 000 feet the corresponding value is 2.06. Since the pressure altitude in this case is exactly halfway between 0 and 1 000, the EPR setting should be halfway between as well. The only possible correction would be for if the air conditioning bleeds are off. Using the data from Operating Conditions R-4 (Figure 4-5), the field elevation is 2 000 feet and the altitude correction is - 100 feet (refer to Figure 4-4), which results in a pressure altitude of 1 900 feet. Since there is no listing for this altitude in the table in Figure 4-6, it is necessary to interpolate. Since the altitude given (1 900 feet) is not halfway between the two table values (1 000 and 2 000 feet), it is necessary to calculate the amount the EPR changes per 1 000 feet of altitude. Determine the difference between the EPR values at these two altitudes (2.11 - 2.06 = 0.05). That means the EPR variation from 1 000 feet to 2 000 feet is 0.05. The EPR variation per 1 000 feet is 0.005 (0.05/10), and the EPR decreases as altitude decreases. To determine the EPR for 1 900 feet, subtract 0.005 from the EPR for 2 000 feet (2.11 0.005 = 2.1 05). The temperature-limited EPR is 2.11. So the take-off EPR for operating conditions R-4 is 2.105. Airbus 320 Take-off EPR
The table at Figure 4-9 is used to determine take-offEPR. Enter the table with temperature and pressure altitude. Each intersection of temperature and airport altitude has a box with one take-off EPR The note for EPR adjustment is located on the top of the table. For example, with an OAT of 28 ·c, an airport altitude of 2 000 feet will result in an EPR value of 1.419. Ifthe temperature and altitude value does not appear in the table, the interpolation is necessary. For example, if the temperature is 27 ·c at a pressure altitude of 1 500 feet, the EPR is 1.418. Since there is no listing for these temperature and altitude in the table in Figure 4-9, it is 76
~A320
IN FUGHT PERFOMANC£
3.05.06
THRUST RATINGS
REV 17
FUG>fT CREW OPfRATING MANUAL
p4
l
SEQ 030
TAKE-OFF EPR
TAKE-OFF EPR
V2SOOA1
EPR I:ORRECltlHS FOR AIR BLEED
-.010
-.010
lfm.r.:£ It(
Q.OOO
-.017
HACfU.E
l>~ll-U
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necessary to interpolate. At 1 000 feet, the EPR for 26 ·c is 1.412. At 2 000 feet the corresponding value is 1.428. Since the pressure altitude in this case is exactly halfway between 1000 and 2 000, the EPR setting should be halfway between as well. Therefore the EPR for 26 ·c at 1 500 feet is 1.420. In the same way, the EPR for 28 ·c at 1 500 feet is 1.416. Since the temperature in this case is exactly halfway between 26 ·c and 28 "C, the EPR setting should be halfway between as well.
77
So the EPR setting for 27 "C and 1 500 feet is 1.418. The possible correction would be for if the air conditioning bleeds are on and anti-ice on. Considering another example, the field elevation is 2 300 feet and the temperature is 16 ·c. Since there is no listing for this altitude in the table in Figure 4-9, it is necessary to interpolate. Since the altitude given (2 300 feet) is not halfway between the two table values (2 000 and 3 000 feet), it is necessary to calculate the amount the EPR changes per I 000 feet of altitude. Determine the difference between the EPR values at these two altitudes (1.443 - 1.428 = 0.015). That means the EPR variation from 2 000 feet to 3 000 feet is 0.015. The EPR variation per 1 000 feet is 0.001 5 (0.015/10), and the EPR increases as altitude increases. To determine the EPR for 2 300 feet, add 0.004 5 (0.001 5 x 3) to the EPR for 2 000 feet (1.428 + 0.004 5 =1.433). So, the take-offEPR in this case is 1.433.
SECTION C
CLIMB PERFORMANCE
Climb performance is important from both economic and flight safety points of view. In a climb, the potential energy of the aircraft is increased and fuel energy must be expended to achieve this. The fuel required to climb to a given height can be minimized by the use of the correct climb technique and optimum economy of operation can be attained. Economy, however, is not the only criterion of operation. The safety of the aircraft depends on its ability to climb above obstructions at all points on the flight path. Sufficient excess thrust must be available to ensure that the aircraft can meet certain minimum gradients of climb in any of the safety critical segments of the flight. The best rate-of~limb speed for any airplane is the speed at which there is the greatest difference between the power required for level flight and the power available from the engines. The LIDMAX speed for any airplane is the one that requires the least power for level flight since it is the lowest drag speed. Because the power output of prop-driven airplanes is relatively constant at all speeds, L/DMAx is the best rate-of-climb speed for them. Turbojet engines produce more power as the aircraft speed increases. Although drag increases at speeds above L/DMAX, the engine's power output increases even more so that the maximum difference between power required and power available is achieved at a higher airspeed. For a turbojet, the best rate-of-climb speed is faster than LIDMAX.
BOEING 737 CL IMB PERFORMANCE TABLES The tables in Figures 4-10 and 4-11 allow you to determine the time and fuel required for a climb to cruising altitude after take-off. The table in Figure 4-10 is for ISA temperatures, and the table in Figure 4-11 is for ISA +10° . Each intersection of Brake Release Weight and Cruise Altitude has a box with four numbers. These are the time, the fue~ the distance and the TAS required to climb from a sea level airport to cruise altitude in calm wind conditions. For example, with a brake 78
weight of 110 000 pounds, a climb to 33,000 feet in ISA +10° conditions will require 26 ...,;nutes, 4 100 pounds of fuel and cover a distance of 154 NM (see Figure 4-11). ~!ease
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A headwind or tailwind component in the climb will change the distance flown. Assume that there is an average 20-knot headwind in the climb described above. The first step is to compute the average "no wind" GS (ground speed). A distance of 154 NM flown in 26 minutes works out to a GS of 355.4 knots. A headwind component of 20 knots will reduce this GS to 335.4 knots. The distance flown in 26 minutes at 335.4 knots is 145.3 NM. Departure from an airport that is significantly above sea level will reduce the fuel required for the climb. Notice that departure from a 2 000-foot airport will reduce the climb fuel by 100 pounds, however the effect on time and distance flown is negligible. Notice that the adjustment values are located at the bottom of the tables in the Figures 4-10 and 4-11. 79
EN ROUTE CLIMB 2801.70 tSA +10 ..."i.'SW.li
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En Route Climb 280/.70 ISA+lO "C
Using the data from operating conditions V-2 (Figure 4-12), with a brake release weight of 95 000 pounds, a climb to 27 000 feet in ISA conditions will require 13 minutes, 2 400 pounds of fuel and cover a distance of 65 NM in calm wind conditions. There is an average 20-knot tailwind in the climb described above. The first step is to compute the average "no wind " GS. A distance of 65 NM flown in 13 minutes works out to a GS of300 knots. A tailwind component of20 knots will increase this GS to 320 knots. The distance flown in 13 minutes at 320 knots is 69.3 NM. Thus, the wind adjusted distance is 69.3 NM. In this case, departure from a 3 000-foot airport will reduce the climb fuel by 150 pounds. Because there is no listing adjustment for this airport elevation in the table in Figure 4-10, it is necessary to interpolate. At 2 000 feet, the reduced fuel burned is 100 pounds. At 4 000 feet the corresponding value is 200. Since the airport elevation in this case is exactly halfway between 2 000 and 4 000, the reduced-fuel should be halfway between as well. However the effect on time and distance flown is negligible. So the fuel burned RO
is 2 250 pounds (2 400- 150 = 2 250). The aircraft weight at the top of climb is 92 750 pounds (95 000 - 2 250 = 92 750). OPERATING CONDITIONS
V-1
V-2
V-3
V-4
V-5
BRK REL WEIGHT (X1 000}
110
95
85
105
75
33,000
27.000
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30HW
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4.0 HW
CRUISE PRESS ALT AIRPORT ELEVATION ISA TEMPERATURE AVG WIND COMP (KTS)
Figure 4-12 B737 En Route Climb Operating Conditions
BOEING 737 CLIMB AND CRUISE POWER TABLES The Maximum climb and Maximum Continuous EPR Table at the top of Figure 4-13 is similar to the one discussed in take-off EPR. In this table two EPR values are found-one for temperature and one for altitude. The lower of the two is the maximum climb/continuous EPR. For example, if the temperature is +10 ·c at a pressure altitude of 10 000 feet, the temperature-limited EPR is 2.04 and the altitude-limited EPR is 2.30 (The altitude-limited EPR is 2.30 from 5 660 feet and up). The maximum EPR is 2.04.
EN ROUTE A!C AIRBLEEO ON
MAX CLIMB & MAX CONTINUOUS EPR 1 TAT C ------
0
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Figure 4-13 B737 Climb and Cruise Power
81
The Maximum Cruise EPR Table in Figure 4-13 supplies one EPR value for a given Total Air Temperature (TAT) in one of two altitude ranges. The correction tables are similar to ones used previously in Figure 4-6 and apply to both tables. Using the data from operating conditions T-2 (see Figure 4-14), the total air temperature (TAT) is 0°C at a pressure altitude of 5 000 feet, the TAT-limited EPR is 2.10 and the altitude-limited EPR is 2.20 (refer to Figure 4-13). The maximum continuous EPR is 2.10. According to the notes about the adjustment to the EPR which are located at the bottom of Figure 4-13, engine and wing anti-ice correction is -Q.l2, air conditioning off correction is+ 0.04. Therefore, the maximum continuous EPR setting is 2.02 (2.10- 0.12 + 0.04 = 2.02). T-1
T-2
T-3
T-4
T-5
TOTAL AIR TEMP (TAT)
+I O ~c
ooc
-15 oc
-30 nc
+lSoC
ALTITUDE
10.000
5.000
25.000
35.000
18,000
ON
ON
ON
ON
OFF
OFF
20N
20N
1 ON
OFF
ON
OFF
ON
ON
OFF
OPERATING CONDITlONS
ENGINE ANTI-ICE WING ANTI-ICE AIR CONDITIONING
Figure 4-14 B737 Climb and Cruise Power Operating Conditions
Refer to Figures 4-13 and 4-14, according to the operating conditions T-4, the total air
·c
temperature (TAT) is - 30 at a pressure altitude of 35 000 feet, the TAT-limited EPR is 2.20 and the altitude-limited EPR is 2.30. The maximum climb EPR is 2.20. Based on the notes about the adjustment to the EPR which are located at the bottom of Figure 4-13, engine and wing anti-ice correction is -o.14. Therefore, the maximum climb EPR setting is 2.06 (2.20 - 0 .14 = 2.06). Using the data from operating conditions T-3 (Figure 4-14), the total air temperature (TAT) is -15 'C at a pressure altitude of 25 000 feet. The maximum cruise EPR is 2.02. According to the notes about the adjustment to the EPR, engine and wing anti-ice correction is -o.12. Therefore, the maximum cruise EPR setting is 1.90 (2.02- 0.12 = 1.90).
AIRBUS 320 CLIMB PERFORMANCE TABLES The tables in Figures 4-15, 4-16, 4-17 and 4-18 allow you to determine the time and fuel required for a climb to cruise altitude after take-off The tables in Figures 4-15 and 4-16 are for ISA temperatures, and the tables in Figures 4-17 and 4-18 are for ISA +10°. Each intersection of brake release weight and cruise altitude has a box with four numbers. These are the time, the fuel, the distance and the TAS required to climb from a sea level airport to cruise altitude in calm wind conditions. For example, with a brake release weight of 120 000 pounds, a climb to 31 000 feet in ISA +10° conditions will require 13 minutes, 2 502 pounds of fuel and cover a distance of 82 NM (see Figure 4-17). 82
~A320
IN FLIGHT PERFORMANCE
3.05.10
CLIMB
REV 18
FLIGHT CREW OI'ERAnNG !IANVAL
p2
1
SEQ 122
CliMB 250 KT I 300 KT I M. 78 MAX. CUMB THRUST
ISA
CG=33.0%
NORMAL AIR CONDITIONING
ANTI-ICING OfF WEIGHT AT BRAKES RELEASE (1000LB)
FL
390 370 350 330 310 290 270 250 240 220 200 180 160
140 120
100 50
15
TIME (MINI DIST.(NM)
fUEL (LB) TAS (KT)
110 120 125 130 135 105 115 16 2522 17 2683 18 2854 19 3037 21 3234 22 3450 24 3692 100 382 107 383 115 384 123 386 132 387 143 389 t55 390 1<1 2378 , 5 2524 16 2677 17 2838 18 3010 19 3192 21 3387 89 375 95 376 101 377 108 378 115 379 123 381 i 31 382 13 2253 14 2388 15 2529 16 2677 17 2832 18 2996 19 3169 80 369 85 370 91 371 97 372 103 373 109 374 , 16 374 12 2138 13 2263 14 2394 14 2530 15 2674 16 2823 ' 17 2981 73 362 77 363 82 364 87 365 92 365 98 366 104 367 11 2024 12 2141 12 2262 13 2388. 14 2520 15 2658 16 2803 66 354 70 355 74 356 78 357 83 357 88 358 93 359 10 1901 11 2010 11 2122 12 2238 13 2360 13 2486 14 2618 59 345 62 345 66 345 69 347 73 347 78 348 82 349 9 1751 10 1849 10 1951 11 2056 11 2165 12 2278 12 2396 50 332 53 332 56 333 59 334 63 334 66 335 70 335 8 1614 9 1703 s 1795 10 1890 10 1989 11 2091 ,, 2196 43 319 46 320 48 321 51 321 54 322 57 322 60 323 8 1548 8 1634 9 1721 9 1812 9 1906 10 2003 10 2103 40 313 43 314 45 314 47 315 50 3\5 52 316 55 316 7 1423 7 1500 8 1580 8 1662 8 1147 9 1835 9 1925 35 301 37 301 39 302 41 303 43 303 45 303 47 304 6 1304 7 1375 7 1522 8 1599 7 1447 8 1678 8 1760 30 289 31 289 33 290 35 290 37 291 38 291 40 291 6 1191 6 1255 6 1321 6 1389 7 1459 7 1530 7 1605 25 276 27 277 28 278 30 278 31 278 33 279 34 279 5 1199 6 1323 7 1455 5 1082 5 1140 6 1260 6 1388 22 263 23 264 24 265 25 265 27 266 28 266 29 266 4 975 5 1080 5 1135 5 1192 6 1250 6 1310 5 1027 21 252 22 252 23 252 25 252 18 250 19 250 20 251 4 916 4 963 4 1012 5 1063 5 1114 4 869 5 1168 15 235 16 236 17 236 18 237 18 237 19 237 20 238 3 695 3 732 3 770 3 809 4 849 4 891 4 934 10 207 11 208 12 209 12 209 13 210 13 210 14 210 2 475 2 550 2 577 3 605 2 452 2 500 2 524 6 170 6 171 6 171 7 171 7 172 7 172 5 169 1 309 1 324 1 281 1 295 1 340 2 356 2 373 2 119 3 , 19 3 120 3 120 3 120 3 121 3 121
LOW AIR CONDITIONING 6 FUEL = - 0.4 % I(GC ~
FROM BRAKES RELEASE PT.
~231
l
ENGINE ANTI-ICE ON A FUEL = + 6.0 %
V2500 211CI0Cl00CSL.B330 0 011690 0 0 2 1.0 500.0 300.0 1 OJ
l
TOTAL ANTI-ICE ON !:. FUEL= + 11.0% FCO.'I\-~ IO.OO:Z·122
Figure 4-15 Climb Performance Table (1)
83
~A320 FLIGKT Cllf\11 OPI!IIAT1NG MANUAl.
IN FUGHT PERFORMANCE
3.05.10
CLIMB
REV 18
p3
l SEQ 122
CUMB 250 KT /300 KT I M.18
MAX. CLIMB THRUST ISA FROM BRAKES REL£ASE PT. NORMAL AIR CONDITIONING CG=33.0% trJME (MIN) FUEl (lB) ANTI-ICING OFF DIST.(NM) TAS(ICT) WEIGI-IT AT BRAKES RELEASE (1000LB) 145 FL 140 15D 155 160 165 170 26 3968 169 393 22 3598 24 3830 25 4086 27 4376 370 141 383 151 385 163 387 178 389 20 3353 21 3549 22 3759 24 3987 25 4238 27 4518 29 4838 350 124 376 132 377 140 378 150 380 161 382 174 384 189 387 18 3147 19 3322 20 3507 21 3704 23 3915 24 4142 25 4392 110 368 117 369 124 370 132 372 140 373 150 375 160 377 16 2954 11 3113 18 3279 19 3454 20 3640 21 3837 23 4048 98 360 104 361 110 362 116 363 123 364 131 365 139 367 15 2756 16 2899 16 3049 17 3206 18 3371 19 3544 20 3728 86 349 91 350 96 351 102 352 107 353 113 354 120 356 13 2518 14 2645 14 21n 15 2914 16 3057 17 3207 18 3364 73 336 77 337 81 337 86 338 90 339 95 340 100 341 12 2306 12 2420 13 2537 13 2659 14 2785 15 2916 15 3053 63 323 66 324 69 324 73 325 16 326 80 327 84 328 11 2207 12 2315 12 2425 13 2540 13 2659 14 2783 14 2911 58 317 61 317 64 318 67 319 70 319 74 320 77 321 10 2019 10 2115 11 2215 11 2317 12 2424 12 2533 13 2647 49 304 52 304 54 305 57 306 60 306 63 307 65 308 9 1845 9 1932 10 2021 to 2113 10 2208 11 2307 11 2408 42 291 44 29Z 46 292 49 293 51 294 53 295 56 295 a 1681 8 1760 8 1840 9 1924 . 9 2009 10 2097 10 2189 36 279 38 280 40 280 41 281 43 281 45 282 47 283 7 1524 1 1595 8 1668 8 1742 8 1819 9 1899 9 1980 31 266 32 267 34 267 35 268 37 269 38 269 40 270 6 1436 6 1372 7 1501 7 1568 7 1636 8 1707 8 1780 26 252 27 253 28 254 29 254 31 255 32 256 34 257 5 1224 6 1280 6 1338 6 1397 6 1458 7 1521 7 1586 21 238 22 238 23 239 24 240 25 240 27 241 28 242 4 978 4 1023 5 1069 5 1117 5 1165 5 1215 5 1266 15 211 15 211 16 212 17 213 18 214 18 214 19 215 3 633 3 662 3 691 3 720 3 751 3 782 3 813 8 172 8 173 8 174 9 115 9 176 10 177 10 178 2 39\ 2 408 2 426 2 444 2 462 2 480 2 499 15 3 121 4 122 4 122 4 123 4 124 4 125 4 127
390
330 310 290 270 250 240 220 200 180 160 140 120 100 50
LOW AIR CONDITIONING ENGINE ANTI-ICE ON t:. FUEL = .!. 6.0 % 6. FUEL "" - 0.4 % ltXlC .Of AJ2G.Zll v.zsoo 211~ o018590 oa 2 1.0 soo.o JOO.Otll3
TOTAL ANTl-ICE ON t:. FUEL=+ 11.0%
Figure 4-16 Climb Performance Table (l)
84
F~1~122
~A320 FLJGKT Cllt'W orEIIATING IIWIUAL
IN FUGHT PERFORMANCE
3.05.10
CUMB
REV 18
p4
1SEQ 122
CUMB 250 ICT /300 KT I M.18 MAX. CUMB THRUST ISA+ 10 FROM BRAK£S RELEASE PT. CG=33.0% NORMAL AIR CONDmONING !TIME {MIN) FUEl (LB) ANT~ICING
FL
390 370 350 330 310 290 270 250 240 220 200 180 160 140 120 100 50 15
OFF
DIST.(NM)
WEIGHT AT BRAKES RELEASE f1000LB) 110 105 115
120 125 130 16 2648 17 2818 18 2998 20 3191 21 3399 23 3628 105 391 113 393 121 394 129 395 139 396 150 398 16 2495 16 2649 16 2810 18 2980 19 3161 20 3353 93 384 100 385 106 386 113 388 121 389 129 390 13 2363 14 2505 15 2653 16 2809 17 2972 18 3144 84 378 90 379 95 380 101 381 108 382 115 383 12 2240 13 2372 14 2509 15 2653 16 2804 16 2961 76 371 81 372 86 373 91 373 97 374 103 375 11 2119 12 2241 13 2369 13 2502 14 2641 15 2786 69 363 73 364 77 364 82 365 87 366 92 367 10 1989 11 2103 12 2220 12 2343 13 2470 14 2603 61 353 65 354 69 355 73 355 77 356 81 357 9 1830 10 1933 10 2039 11 2150 11 2264 12 2383 53 340 56 341 59 341 62 342 66 343 69 343 8 1685 9 1778 9 1875 10 1975 10 2078 11 2185 45 327 48 328 51 329 53 329 56 330 59 330 8 1616 8 1705 9 1797 9 1892 10 1990 10 2092 42 321 44 322 47 322 49 323 52 323 55 324 7 1483 7 1565 8 1648 8 1734 9 1823 9 1915 36 308 38 309 40 310 42 310 45 311 47 311 6 1359 7 1433 7 1508 7 1586 8 1667 8 1750 31 296 33 297 34 297 36 298 38 298 40 298 6 1240 6 1307 6 1376 71447 7 1520 7 1595 27 283 28 284 30 285 31 285 33 286 34 286 5 1126 5 1186 6 1248 6 1312 6 1378 6 1446 23 271 24 271 25 272 26 272 28 273 29 273 4 1013 5 1068 5 1124 5 1181 5 1240 6 1301 19 257 20 258 21 258 22 259 23 259 24 259 4 903 4 951 4 1001 5 1052 5 1105 5 1159 16 242 17 242 17 243 18 244 19 244 20 244 3 720 3 759 3 799 4 840 4 882 4 925 11 214 11 215 12 216 13 216 13 217 14 217 2 467 2 492 2 517 2 543 2 570 2 598 6 176 s tn 6 178 7 179 7 179 7 180 1 289 1 318 1 303 1 334 1 351 2 368 3 127 3 127 3 128 3 129 3 129 3 129
LOW AIR CONDITIONING 6. FUEL = - 0.4 %
ENGINE ANTI-ICE ON 6 FUEL = + 6.0 %
TAS{KT}
135 24 3883 163 400 21 3559 138 391 19 3327 122 384 17 3127 109 376 16 2937 97 368 14 2741 86 357 13 2506 73 344 11 2296 62 331 11 2197 58 324 9 2010 49 311 8 1836 42 299 8 1673 36 286 7 , 516 31 273 6 1364 26 260 5 1215 21 245 4 970 15 217 3 627 8 180 2 386 3 130
TOTAL ANTI-ICE ON 6 FUEL = + 11.0 %
HXIC -04 ~231 V2SOO 21100l00CSI.Bnl 0 01ai9J o 0 2 1Jl !iOO.O 300.D I 03
Figure 4-17 Climb Performance Table (3)
85
'$JA320I ~IGKTCIIEWotEMTINliW.I'.lJAL I
rr~
fUGHT PERfORMANCE
3.05.1 0
CLIMB
REV 18
p5
j SEQ 122
CUMB 250 KT I 300 KT I M.18 MAX. CLIMB THAUSi !SA+ 10 FROM BRAkES RELEASE PT. NORMAL AIR CONDffiONING CG=33.0% 11ME (MIN) FUEL (LB) ANTI-ICING OFF DIST.(NM) TAS(KT) WEIGHT AT BRAKES RELEASE (1000LB) Fl 140 145 150 155 160 165 170 21 4175 178 402 23 3782 24 4027 26 4298 28 4606 148 392 159 394 172 396 187 398 20 3521 21 3728 23 3950 24 4192 26 4457 28 4754 30 5094 350 130 385 _138 386 148 387 158 389 170 391 183 393 199 396 iS 330:.! 19 3487 21 3682 22 3890 23 4113 25 4354 26 4619 330 115 377 123 378 130 379 138 381 147 382 157 384 168 386 17 3097 I 18 3264- 19 344{) 20 3624 21 3820 22 4028 23 4252 310 l03 362 \09 369 115 370 122 372 129 373 137 374 146 376 15 1ses 16 3037 \7 3195 18 3361 19 3534 20 3717 21 3912 91 358 96 359 101 360 107 361 113 362 , 19 363 126 365 13 2635 14 2768 15 2907 16 3051 16 3202 17 3360 18 3526 77 344 81 345 85 346 90 347 94 348 99 349 105 350 12 2411 12 2530 13 2653 14 2781 14 2914 15 3052 16 3197 66 331 69 332 72 332 76 333 80 334 84 335 88 336 11 2306 12 2419 12 2535 13 2656 13 2781 14 2911 15 3047 61 324 64 325 67 325 70 327 74 327 17 328 81 329 10 2108 10 2209 11 2313 11 2421 12 2533 12 2648 13 2769 52 312 54 312 57 313 60 314 62 314 65 315 68 316 9 1S24 9 2016 10 2109 10 2207 tl 2307 11 2410 12 2517 44 299 46 300 49 300 51 301 53 302 56 302 58 303 1 8 1753 8 1835 g 2097 9 1920 9 2007 0 2190 10 2286 38 286 40 287 41 288 43 288 45 289 47 290 50 291 7 1588 7 1652 8 1738 8 18H 8 1898 9 1982 9 2068 160 32 274 34 274 35 275 37 275 38 276 40 277 42 278 0 1429 8 1495 7 t563 7 1634 7 1706 a 1781 8 1858 27 260 28 260 29 261 31 262 32 263 34 264 35 265 5 1273 6 1393 6 1455 6 1332 6 1520 7 1586 7 1655 22 245 23 246 24 246 25 247 27 248 28 249 29 250 4 1017 4 1064 5 1113 5 1162 5 1214 5 1267 5 1321 15 218 16 218 17 219 18 220 19 221 19 222 20 224 3 655 3 686 3 717 3 749 3 781 3 814 3 848 8 180 8 181 9 182 9 183 10 185 Hl 186 11 187 2 423 2 441 2 404 2 461 2 480 2 500 2 520 4 130 ~ 131 4 132 4 133 4 135 5 136 5 138
390 370
I
290 270 250 240 220 200 180 140 120 100
50
15
LOW AIR CONO.TIONING L FUEl. = - (I ~ 0/o
.
.
ENGINE ANTI-ICE ON !:. FUEL = + 6.0 %
TOTAL ANTI-ICE ON b. FUEL=+ 11.0%
Hl3C .o.t A$2!).~31 '12500 .tl1o:nxK:Sl itn1 0 01159:l 0 G2 1,1) SOO.O XIO.O 1 03
Figure 4-18 CJimb Performance Table (4)
86
F~lo.W>122
AIRBUS 320 CLIMB AND CRUISE POWER TABLES The maximum climb, maximum continuous and maximum cruise EPR tables in the Figures 4-19, 4-20 and 4-21 are similar to the one discussed in A320 take-offEPR. Enter the tables with temperature and pressure altitude. Each intersection of temperature and altitude has a box with one take-offEPR. The note for EPR adjustment is located on the top of the tables.
~A320
IN FUGHT PERFORMANCE
3.05.06
THRUST RATINGS
REV 17
FLIGHT C/leN OP£RATING IUMJA1.
p8
ISEQ 030
MAXIMUM CUMB EPR
V2500A1
MAXIMUM CLIMB EPR
EPR CORRECTIOOS
F~
All~~
HA..~
At() ~ ~
A.'f'l"i-a
0
0
0
0
0
...' ~
0
011
-.113:)
ALTITUDE
IFTl
~1000.
sooo.
7000. 11000. 15000. 19000. 2$000, 27000. 31000. 35000. 59000.
-54.0 -50.0
1.2&2
\.'262
1. 296 1. '29£,
1.3221 1.:r.12
1.331 1.331
-46.0 -42.0
\.262 \. 21i2
I. 295
1.322
1.m
1.331 1.33\
)~S'$9
1.296
1.3al t.l!31 1.331 1.:!31
1.359 t. 359
1.2':16 1. 296 ,_ 2':16
-26.0
1.262 1.262 1.262 -:. 21i2
-:22.0 -18.0 -14. 0 -10.0
1.262 1. 21i2 1.262 1. 262
1. 296 1. 29S 1.:1'l6 1.2':16
-2.0
1..262 1.2£2
2.0 6.0
1.2£'2
~6.0
~
• 018
-.018
(0
-ss.o
0
l
t:FF ()I
-34.0 -30.0
...... .. ...' "'. "'
250/280/.?6
AR Sl.EED
IUlCall iUITH:f
TAT
.
AR COI\'O ON
10.0 14.0 18.0 22.0 20.0
30.0 34.0
sa. o 42.0
1.~2
1. 262 1.26'2 '1.262 1.262
'1. 26'2 1.2£2 1. 2£2 1.251
50.0
\.ZlS 1.220 1.205
54. 0
1.192
.:&.0
1.296
t.m 1.322 1.:22 1.m
1.359
1.:JS8
'U01
\. (2&
1.~0
\.~92
1. 'II&
1.!59
1.388
1.~1
i.~28
1.
1. 19&
1.!!88
1. '!11 1.1.01
!.'23 7.423
\.~0
l. ,92 1.,\l2
1.~to
1.~92
1. ''Jib
\,'50
,,,92
I. ,s:; l.<~~ ,
t. ,9;1 ,_ (92
1.@ '
\. 497
'· SS'J
\.1:59 1.359
1.3110
'·*
\. '!)1
t. , ,,
1.~1
,_ '211
I
t. '!11
1.:!E11 \.381
1.~1
l.~i
1.<50
1.497
,_ (96
\.(01
'1.<28 I
\.~
-..m
1.388 1.388
l. 401 l, '!)1
,.4~
1.(50
I. COl
1.
i.
i ue ~2!!,
I
,, 3:11
1.S22 1.a:22
\.331 1.331
1, 296 1.296 1. 296 1. 296
1.a:22 1.32'2 1.m 1.322
1.:!31 1.331 1.531 1.331
1.3$9 1.m \,3S9 l.!S9
1.388
1. 401
1.388 1.1188 1.388
,, '01 1.392
'1.
1.$8
1. Zl6
1.322
\.3$9 \.346 1.324 1.!02
1.365
\.ll'-'
'I.::IY
1.?36
1.331 l.:!3l 1.330 1.309
1.3~2
\.320
\. 314
1.330 \.3(;$
'·'" 1.291
i.~
,.~~
.. ztJ'
'\.~
t. IV'l
1.'2156
l.Zl; '
1.~
1.:159 1.359 I.JS9 L3S~
1. 2Sfj
\.322 1.322
1.~,
1.320
1.2So \.228 1. 271 1. 254
t.SOO
'.238
1.261 1. 263
'1.269 '\.~
1. 2111 1.262 1,2((
1.2~
1.<:3'
1.221
\. T.S2 1. 218
'1.218
1. 2'1C
1. 238 1. 223 1. 210 1.\W
t. ' " '· l!o
l.m8 1.388 1.380
1.m l. 3:22
'1.331
u~;
1. 777 1.257 1.239 1.221
1.:235
1.203
1. 20~
I
1. 496 1.'96
1. ~s
,, .;so
1. 4113 1.<160
1. 44S
\.~
l.t,~
1.~
1.~21
1. ~1:1
~17
1. 4('.-1
\.39.>
1.1slla
t.31."'
t.m
'1.3!.2
~.3S(
1.~1!
.
l.:VS
'1.!65
1.850
1.313
13:8
\.32n
\.306
II i
X
Figure4-19
Maximum Climb EPR Table
87
$A320
IN FUGHT PERFORMANCE
3.05.06
THRUST RATINGS
REV 17
FLICilfr CJIEW OPERATl NG NNI'.JAl.
p7
ISEQ 030
MAXIMUM CONTINUOUS EPR
V2500A1
MAXIMUM CONTINUOUS
EPR CORRECTIONS
FOR AIR
Aacootnt'o'G
EPR
AIR COND
llNVC=230
BlfEO .017
ct=1'
-,017
1¥\CEUE A...n-tf Ill NIICI3.L£
~fiHCE A/f) Ql&
AIITI-tf
-.r:t!l
1)1
ALTITUDE
TAT ct>
-54.0
L~
1.~26
1.-"'0
1.46~
1.~
1.~9
1.311
,.~20
,.~
1.439
1.~9
1.Z'8 1. 278
1.311
1. ;25 1.426
1.470
1.464 1.464
1.~
--42.0
1.364 1. 364 1. 364
U70
1.~M
1.~
1. <169 1.469
1.4M l.4M 1.4M 1.4M
1. L39
1.469
1.~
1.~9
1.\.:-9
1.469 1.469
-38.0
1.?18
1.311
1. 711!
1.311
-30.0 -2&.0
l.2n l.ml
-u.o -10.0
-6.0 -2.0 2.0 &.0
c
.. c 0
I
"'...
..... 0
I
0
I
.... ... 0
1.426
1,~0
t~2ii
1.470
t.an
1. 31>4
t 42!i
l.QO
1. 311
1.304
!. 426
1. ,70
1. 311 1.311
t.~
1.426
1.470
1.~
1. 426
1.311 1.$11
1. 304
1.426
1.~
1.426
1.m '1.470 L470
t~
1.(20
,,,70
1. 364
l3li4
i. 426 1. ,26
1.470
1.178
1.311 1.311 t. 311
l.~
1.178
M1l
,.~
!.4~
1. ~0
1.178 1. 178
MM 1.4M 1.4M 1.464 1.464 1.46' 1.454 1.430
1.(~
t~
1• .;3';) t. ~ 1.~
i.~
1. ,,,
t. .W
1. 389 1.~
1.3!1 1.35?
1.339
tJn
1.304
KO
1.'26
1."9
1. 278
1.311
).3M
1.4~
1.382
18.0 22.0
,, 278
1.:llt
1.31>4
1. 422 1. 401
1.~
1.359
1.318 "..296
1.278
1.an
1.357
\.381
1.378
1.337
'\.2?0
1. 278 1.778 1, ?tS
t.3l1
1.344
1.~1
1.35?
1.316
1.al1
l. 331
1.~
1.~
t~
1.~
25~
1.278
1.3Zi 1.305
1.317
t
1.3?0 l.305
42.0 4&. 0
1. 251 1.Z39
1.288
1.267
54.0
1.228 ... ~15
1.258 1.253 1. Z3'J
10.0
2&.0
ss.o
so.o
\. 469 1. <169 t. 469 1. <457
1.13S
, ,~
3<.0
0 0
t.m 1.278 1.278 1.178
1.3M 1.3M
, , 713
c .... ao.o 0
1.3)1
-34.0 -22. 0. -18.0
'
-1000. 3000. 7000. 11000. 15000. 19000. 23000. 27000. 31000. 35000. 89000. 1.311
-46,0
~
(FT1
1.?78 1.?78
-50.0
1.493 1. ,93 1.493 1.493
t.S09 1.509 1.509
1. '"' ,,,94
1.509
1.4~
1.493 1.493 1.493 1.493
1.509
1.494 1.494 1.(94 1. 494
1.Sll9 1.>09 'I. SIS
l.SOS
1.4~
l.~CJJ
1. -'85
t. (77
1;473
t. ~63
1.~49
1. 4~
\.416
1.~
1.383 1.360
1.3:)$
1.330
1.317
,, 312 1.291
1.006
1.220
Note : 1pack operative on remaining engine. Figure 4-20 Mnimum Continuous EPR Table
I
'· ~
1.430
1.394
1.3?2 1."'9
1. ~73 '!.258
H~
1.493
1.424 1.399 1.370 1.353
'"'
88
KT
~.a
'1.315
~A320
lN FUGHT PERFORMANCE
3.05.06
THRUST RAliNGS
REV 17
FlJGlfT CAEW OPE IIAnNG MAMIAL
p9
JSEQ 030
MAXIMUM CRUISE EPR
V2500A1
!MAXIMUM CRUISE EPR
EPR ctJ{REC:TilNS
fOR AlR BLEED
IIAC8..l.f ftlffi-0: liN
-. 018
~n-ICE
!CI -~.0
-so.o
-46.0 -42.0 -38.0 -3~.0
-30.0 -26.0
-22.0
AMI lmQ AIITHl! 011
-.030
AlTITUDE a=n
l. 192
1.226 1. 226
1.252 1.252
1.22S 1. 226
1.25'2 1.252
1. 225 \,226
1.226
1.252 1.252 I, :152
1.226
1.252
), 2'26
1.~
l. 226
1. 252 '\.252 1.252
\.192 1.192 L 1~
10. 0
1. 1!12 1.192 1.192 1.192
1~.0
... .... 0
2&.0
0
30.0 34.0 38.0
...e ...
1.252
1.192 1.192 1. 192 1.192
16.0 22-0
0
1. 225 1.226 t. 225 t. 226
-6. 0 -2.0 2.0 6.0
c
... •
I. 19:2 \.19:2 \. 1~ 1.192
- 10.0
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1.\33
Maximum Cruise EPR Table
89
SECTION D
CRUISE PERFORMANCE
Since an aircraft usually spends the greater part of its mission in cruising flight, the cruise performance has a strong influence on the overall mission performance. The cruise performance of an aircraft is one of the fundamental building blocks of the overall mission. In the cruising segment of the mission, both height and airspeed are essentially constant and the aircraft is required to cover distance in the most expedient manner. Usually, the majority of the fuel carried in the aircraft will be used during the cruise. The distance that can be flown, or the time that the aircraft can remain aloft, on a given quantity of fuel are important factors in the assessment of the cruise performance. civil transport operations, the cruise performance of the aircraft has a strong influence on the economics of the operation of the aircraft. The cost of fuel contributes to the cost of the operation, but so does the cost of time. The aircraft needs to be flown at a speed and in a manner that will optimize the overall operating cost; cruise performance is important to the overall balance between fuel consumption and the time of flight In the analysis of cruise performance, the aircraft is considered to be in steady, level, straight, symmetric flight with no acceleration or maneuver. [n
The maximum range speed for an aircraft is determined by its LID curve. Propeller-driven airplanes wiU achieve best range performance if they are flown at the speed that yields LIDMAx· It is important to find out the difference between the angle yielding L/DMAX and the best angle of climb. Maximum range and glide distance is achieved at LIDMAX. Best angle of climb is at a high angle of attack with both high lift and high drag coefficients, which would not result in a maximum LID ratio. Furthermore, another term we should know is maximum endurance. It would be obtained at the point of minimum power required, since this would require the lowest fuel flow to keep the airplane in steady, level flight. This is not at maximum LID. In turbojet aircraft, a somewhat more complex relationship between lift and drag determines best range. Thrbojets always have a best range speed higher than L/DMAX· Maximum range is obtained at the aerodynamic condition which produces a maximum proportion between the square root of the Lift coeft1cient and the drag coefficient. It occurs where the proportion between velocity and thrust required is greatest. This point is located by a straight line from the origin tangent to the curve, and is consequently at a higher airspeed than L!DMAX· A headwind or tailwind will affect the miles per unit of fuel burned. If an airplane is operating at its best-range airspeed and encounters a headwind, it should speed up to minimize the time in the adverse wind. By the same token, an airplane with a tailwind can slow down and let the wind maintain its ground speed with a lower fuel flow. The exact amount of airspeed change that is useful varies with airplane type. It is only necessary to consider wind velocity effect on cruise speed at wind velocities that exceed 25 percent of the zero wind cruise speed. Turbojet engines have a strong preference for operations at high altitudes and airspeeds. Both lower temperatures and higher altitudes increase engine efficiency by requiring a lower fuel flow for a given thrust. Besides increased engine efficiency, lift and drag both decrease at higher altitude,
90
so less thrust is required. Turbine engines are much more efficient when operated at the upper end of their RPM range. Generally, the optimum cruise altitude for a turbojet airplane is the highest at which it is possible to maintain the optimum aerodynamic conditions (best angle of attack) at maximum continuous power. The optimum altitude is determined mainly by the aircraft's gross weight at the beginning of cruise. As an aircraft burns fuel and becomes lighter, the optimum cruise altitude slowly increases to improve the specific fuel consumption of the engines, meanwhile, the speed and power setting that yields the optimum cruise performance slowly decreases to maintain the optimum lJD ratio. The optimum angle of attack does not change with changes in weight. Since it is seldom practical to change speed and altitude constantly, it is common procedure to maintain a constant Mach cruise at a flight level close to optimum. As fuel is burned, thrust is reduced to maintain the constant Mach number.
SECTION E LANDING PERFORMANCE All conventional aircraft flights end at the destination with a landing. In this phase, the aircraft is transferred from the airborne state to the ground-borne state and brought to a halt Since the maneuver takes place in close proximity to the ground, and at low airspeed, there is relatively high risk to the safety of the aircraft. The maneuver must be carried out in a manner that will reduce the risk of an incident occurring to an acceptably low level of probability. In the landing phase of the flight, the aircraft is on a descending flight path towards the runway As it approaches the runway, the airspeed and the rate of descent are reduced in the flare so that a touchdown is achieved at a low rate of descent. After touchdown, the nose is lowered onto the runway and the aircraft brought to a halt. During the landing, consideration is given to the need to ensure that the aircraft can be controlled safely and that the distances required for the maneuvers do not exceed those available. In this section, we will discuss landing performance considerations, which mainly includes the definitions of some airspeeds and hydroplaning, and how to master landing performance tables and graphs.
LANDING CONSIDERATIONS At the beginning, it is important for us to understand some defmitions about speed. Vs - stalling speed or the minimum steady flight speed at which the airplane is controllable.
Vso- stalling speed or the minimum steady flight speed in the landing configuration.
Vs1 -
stalling speed or the minimum steady flight speed in a specific configuration.
VREF-
reference speed. It is normally 1.3 x V50 .
VLE- maximum landing gear extended speed. 91
VLO!Mw- maximum speed for operating the landing gear. Even with all the aircraft's high lift devices extended, a typical air carrier airplane has a hig approach speed and a long landing roll An airplane is normally flown at 1.3 times the Vso speed fc the aircraft's weight Of course, 1.3 times Vso is an indicated airspeed and the ground speed wi vary depending on wind, altitude and temperature. A high temperature or high altitude approac will increase an aircraft's ground speed for any given approach speed.
An airplane landing at high elevation airports with comparable conditions relative t temperature, wind, and airplane weight has higher groundspeed than at low elevation. An aircraft < high altitude will land at the same indicated airspeed as at sea level but, because of the reduced a density, the true airspeed will be greater. Given the same wind conditions, this will also make th groundspeed higher than at sea level. Once an airplane has touched down on a runway there are 3 ways of slowing it to a stot aerodynamic braking, use of the wheel brakes, and reverse thrust. Aerodynamic braking is not ver effective in slowing large jet aircraft and so it is generally not used to a great extent Reverse thru: is effective mainly at higher airspeeds. The wheel brakes are effective at all speeds and are th primary means of stopping the aircraft. The typical technique for stopping an aircraft on a normal landing is to apply reverse thrust(< prop reverse) immediately upon touchdown. This takes maximum advantage of reverse thrust whe it is most effective and it saves wear on the wheel brakes, which heat up very rapidly at high groun speeds. Shortly after touchdown, the spoilers are deployed. This reduces lift and increases drag. A the aircraft slows, the main wheel brakes are applied to bring it down to taxiing speed. The brak:~ are most effective when lift has been reduced (by spoilers and low airspeed) and more of tl: aircraft's weight is carried by the landing gear. Wheel brakes are at maximum effectiveness when the weight of the airplane is used to hold tl: tires in contact with the runway and the rate of wheel deceleration (or slowing) is just below th: which would induce a skid. To place the maximum weight on the tires it is necessary to reduce li as soon as possible after touchdown by lowering the nose wheel to the runway and deploying win spoilers. Wheel brakes become more effective as an airplane decelerates (or slows down) becam of loss of residual lift as the airspeed decreases. Water on a runway will increase the landing rollout because the reduced coefficient of frictio makes the wheel brakes less effective. This is particularly true at high ground speeds. A very dangerous possibility when landing on a wet runway is hydroplaning. Whe hydroplaning occurs, the wheel brakes are almost totally ineffective. This not only greatly increast the landing rollout, but also introduces the possibility of losing directional control on sliding off tt side of the runway. There are three types of hydroplaning. Dynamic hydroplaning occurs when a tire rolls through standing water, forms a bow wav and then rolls up on top of the wave, losing all contact with the runway. Water about l/1 Oth of~ inch deep acts to lift the tire off the runway. The minimum speed at which dynamic hydroplanir can start is related to tire pressure. As a rule of thumb, dynamic hydroplaning will start at spee<
92
~vughly
nine times the square root of the tire pressure in pounds per square inch. The practical !;>plication is that your nose wheel can hydroplane at a lower speed than the mains because of its lower pressure. Once dynamic hydroplaning has started, it can continue to much lower speeds. For example, an aircraft with main tires having a pressure of 121 PSI could encounter dynamic hydroplaning at roughly 99 knots minimum speed (square root of 121 = 11, 11 x 9 =99). Viscous hydroplaning occurs when there is a thin film of water covering a smooth surface such as a painted or rubber-coated portion of the runway. Viscous hydroplaning can occur at much :ower speeds than dynamic hydroplaning. Either the moisture or the originally slick surface could cause problems, and the combination is especially dangerous. Viscous hydroplaning occurs due to the viscous properties of water. In this type, a thin film of fluid (not more than l/1 000 of an inch in depth) cannot be penetrated by the tire and the tire rolls on top of the film. This can occur at a much lower speed than dynamic hydroplaning but requires a smooth acting surface. Reverted rubber hydroplaning occurs during a locked wheel skid. Water trapped between the tire and the runway is heated by friction, and the tire rides along a pocket of steam. Reverted rubber hydroplaning occurs when the tires of the aircraft are actually riding on a mixture of steam and melted rubber. It would typically occur if excessive braking kept a wheel from rotating. When landing on a water-covered runway, fly the approach as close to "on speed" as possible. Landing at a higher than recommended speed will greatly increase the potential for hydroplaning. After touchdown, use aerodynamic braking and reverse thrust to maximum possible extent, saving the use of wheel brakes until the speed is low enough to minimize the possibility of hydroplaning. Since occurrence of dynamic hydroplaning is related to speed, it is prudent to slow the aircraft with spoilers, reverse thrust, etc., as much as possible prior to applying the brakes. If hydroplaning is experienced on landing, the best method of speed reduction is to apply aerodynamic braking to the fullest advantage. Otherwise, applying full main wheel braking may increase or compound the problems associated with hydroplaning. If any brakes are used, a pumping or modulating motion like an antiskid system can be used. Aerodynamic braking is recommended. Furthermore, abrupt use of either the nose wheel or main wheel brakes will lock the wheels and compound the problem. Landing at a higher-than-recommended touchdown speed will increase hydroplaning potential regardless of braking. Hydroplaning is most likely to occur during conditions of standing water or slush on a runway with a smooth textured surface. The higher the aircraft speed, the more likely it is to hydroplane. Regulations require that when a turbojet aircraft is dispatched to an airport where the runway are forecast to be wet or slippery, the effective length of the landing runway must be 115% of what is required under dry conditions. Since runways cannot be lengthened, the effect of this rule is to lower the maximum allowable landing weight of aircraft on wet runways for dispatch purposes. No person may take off in a turbojet-powered aircraft when the appropriate weather reports and forecasts, or combination thereof, indicate that the runway at the destination airport may be wet or slippery at the estimated time of arrival unless the effective runway length at the destination airport is at least 115% of the runway length required for a landing on a dry runway. For the 93
turbopropeller aircraft, 70 percent of the actual runway available from a height of 50 feet over tt threshold is required.
LANDING PERFORMANCE TABLES AND GRAPHS The graphs in Figures 4-22 through 4-25 are used to compare landing distances under variot conditions. All the graphs are used in the same manner; enter at the bottom with the gross weigh draw a vertical line to the appropriate diagonal line, and from there draw a horizontal Jine to tt landing distance. LAt'IIDING DISTANCE OOMPARISON
CRY RU\lWAY SEiA LEVEL 5!1 ''F 40'' FLAPS ANTI-SKI O OPFAATIVE BRAKES & SPOILERS AI'PLJEO 2 SECONDS AFTER TOI.IC".JOOWN AE\IEASEAS INIT'I\TE£l J SECONDS 1\FTER TOUCHDOWN ENGINE SPIN-UP nME FO'l REVERSE THRUST IS J;.J SECO~OS. CE'RllFIED !.ANDING PAAAM:TERS USED. EXCEPT REVERSE Tl RUST VIHICH IS FLIGHT TEST DA.T.A
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GROSS WEIGHT - 1,000 LBS
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Figure 4-22 B727 Normal Landing- Dry Runway
94
For example, refer to Figure 4-23, one typical question to use these graphs is: which of the iollowing configurations will result in the shortest landing distance over a 50-foot obstacle to a wet runway? 1) Brakes and spoilers at 122 500 pounds gross weight; 2) Brakes and reversers at 124 000 pounds gross weight; 3) Brakes, spoilers, and reversers at 131 000 pounds gross weight
LANDING DISTANCE COMPARISON WET RUNWJ\V
SEA LEVEl 59 ''F 4C•FLAPS
ANn-sKJO OPERATNE BRAKES !'. SPOILERS APPLIED 2 SECONDS AFlER TOUCHDOWN REVERSERS INITIATED 3 SECONDS AFTER TOUCHDOWN. ENGINE SPIN-liP TIME FOR RE"VEASE THRUST IS 6 3 SECONDS. CERTIFIED LANDING PARAMETERS USED, EXCEPT REVERSE THRUST WHICH IS RIGHT FLIGHT TEST ;)ATA.
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NORMAl lANDING Figure 4-23 B727 Normal Landing - Wet Runway
95
This question asks for a comparison of a 40°-flap landing on a wet runway using three different weights and stopping techniques. Line 1 is the distance using brakes and spoilers at a weight of 122 500 pounds. Line 2 is the distance using brakes and reversers at a weight of 124 000 pounds. Line 3 is the distance using brakes, spoilers, and reversers at a weight of 131 000 pounds. The graph shows that Answer 3) will have the shortest stopping distance (about 3 200 feet). Refer to Figure 4-24, landing on an icy runway at a gross weight of 134 000 pounds, air distance is 950 feet, air and transition distance is 1 350 feet. The transition distance is 400 feet (1 350 - 950 =400).
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NORMAL LANDING Figure 4-24 B727 Normal Landing -Icy Runway
96
The graph in Figure 4-25 is used to determine landing distances \Vith touci::c"-ri
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point under various flap position conditions. For example, a 0° flap landing at a .a.-.:b£ 1'e.;::..tt of
119 000 pounds will require about 3 500 feet landing distance and, a 15° flap land.ng
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weight will require about 2 700 feet landing distance. So the ground roll distances are : 500 feet (landing distance is 3 500 feet, touchdown point is 1 000 feet, ground roll eqt!a! 3 500 feet subtracting 1 000 feet) and 1 700 feet (for the same reason) respectively.
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NORMAL LANDING Figure 4-ZS B727 Normal Landing Distance Comparison
97
The graphs in Figures 4-26 and 4-27 are used to determine the thrust required to maintain a given airspeed with various flap configurations with the landing gear both up and down. The graph in Figure 4-27 is for a 110 000-pound aircraft, while the graph in Figure 4-26 is for a 140 000-pound aircraft. Notice that the solid curved lines represent the level flight and that the two dashed lines represent a 3° glide slope.
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Figure 4-26 B727 Landing Thrust- 140 000 Pounds
98
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Figure 4-27 8727 Landing Thrust- 110 000 Pounds
The two graphs work in a manner similar to those in the previous questions. Enter the graph at the bottom with the airspeed, draw a vertical line to the appropriate curved line and then draw horizontally to the required thrust. The two dashed lines represent an approach condition, and the VREF speed is marked with a line and circle on each of the curves. For example, VREF for a 140 000-pound airplane with 40° flaps is 123 knots, and with 30° flaps it is 127 knots. According to these two dashed lines, it is clear that the maximum charted indicated airspeed while maintaining a 3° glide slope at a weight of 140 000 pounds is 156 knots. Furthermore, in this case (refer to Figure 4-26), required thrust is
99
16 200 pounds. Refer to Figures 4-25 and 4-26, one typical problem is what approach speed and ground roU will be needed when landing at a weight of 140 000 pounds if flap position is 15° . The diagonal line for 15° flaps in Figure 4-25 states that the VREF speed is the 40° flaps VREF speed plus 15 knots.
In Figure 4-26, at 140 000 pounds, the 40° flap VREF is 123 knots, so the 15° VREF is 138 knots (123 + 15). Refer to Figure 4-26, another typical problem is what is the change of total drag for a 140 000-pound airplane when configuration is changed from flaps 25°, gear down, to flaps 0°, gear up, at a constant airspeed of 165 knots. In level flight, total thrust and total drag are equal. So, drag with 25° flaps, gear down is 20 300 pounds and drag with 0° flaps, gear up is 9 800 pounds. Change in drag (thrust) is 10 500 pounds. The main difference between Figure 4-26 and 4-27 is the gross weight. For example, refer to Figure 4-27, the thrust required to maintain a 3° glide slope at 110 000 pounds, with gear down, flaps 30°, and an airspeed of VREF + 15 knots is 10 700 pounds (VREF + 15 = 126 knots). According to the figure, the thrust required to maintain level flight at 110 000 pounds, with gear up, flaps 25° , and an airspeed of 155 knots is 14 900 pounds. Some problems require the computation of headwind, tailwind and crosswind components. The wind direction, wind speed and course must be known. Most often these problems are part of a take-off or landing computation. If this is the case, the course corresponds to the runway number (i.e., Rwy 35 = 350° magnetic), and the winds are references to magnetic north and in knots. Determine the headwind and crosswind components for an aircraft landing on runway 35 with the winds form 300° at 20 knots. The crosswind is -15 knots (a negative crosswind is from the left, a positive is from the right). The headwind component is -13 knots (a negative number indicates a headwind, a positive indicates a tailwind). The landing speed table in Figure 4-28 is used to determine the aircraft's approach speed (VREF) at various weights and flap settings. For example, the 100 000-pound airplane using a 30° flap setting has a VREF of 135 knots. This speed is adjusted by adding one half of any headwind component as noted at the bottom of the table. Gust corrections are not required on this test. If the headwind component were 13 knots, the correction would be 7 knots (always round up) and the corrected
VREF would
be 142 knots.
The go-around EPR table at the top of Figure 4-28 is similar to the one discussed for take-off EPR. In this table there are two EPR values: one for temperature and one for altitude. The lower of
·c
the two is the go-around EPR. For example, if the temperature is 15 TAT at a pressure altitude of 500 feet, the temperature-limited EPR is 2.00. The altitude-limited EPR is 2.01 (you need to interpolate between 2.04 and 1.98). There are possible corrections for air conditioning OFF and for engine and wing anti-ice ON. Notice that there are three different temperature scales. Using the data from operating conditions L-3 (Figure 4-29), because of the gross weight of 90 000 poundc; and IS' flaps setting, the table value for reference speed (VREF) is 141 knots (refer to Figure 4-28). According to Figure 4-30, the headwind is 15 knots, so the wind correction to VREF is 100
8 knots (one half of the headwind component is 7.5, the correction always round up). The reference speed is 149 knots (141 + 8 = 149). In this case, the maneuvering speed is 150 knots.
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1..-1
L-2
L.-3
L-4
L-5
+15 oc
...27 °F OAT
-8"C OAT
-1o~c
TAT
TAT
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WEIGHT (XHXJO)
100
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30,
25°
40''
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04
27
34
09
300,'~0
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3Hl/?O
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130115
OPERATING CONDITIONS TEMPERATURE PRESSURE ALTITUDE
RUNWAY ASSIGNED SURFACE WIND
i
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Figure 4-29 B737 Landing Operating Conditions
101
I
V11ND
I COMPONENT
Figure 4-30 Wind Component Chart
From the operating conditions L-4, the maneuvering speed is VREF (refer to Figure 4-28). In this case, the table value for VREF is 134 knots, and wind correction is 3 knots, therefore the
corrected VREF is 137 knots. The maneuvering speed is 137 knots. Using the data from operating conditions L-4 (Figure 4-29), the temperature scale is -I 0 ·c TAT at a pressure altitude of 2 100 feet Since there is no listing for this altitude in the table in Figure 4-28, it is necessary to interpolate. Since the altitude given (2 100 feet) is not halfway between the two table values (2 000 and 3 000 feet), it is necessary to calculate the amount the EPR
102
changes per 1 000 feet of altitude. Determine the difference between the EPR values at these two altitudes (2.15- 2.09 = 0.06). That means the EPR variation from I 000 feet to 2 000 feet is 0.06. The EPR variation per 1 000 feet is 0.006 (0.06/1 0), and the EPR increases as altitude increases. To determine the EPR for 2 100 feet, add 0.005 to the EPR for 2 000 feet (2.09 + 0.006 =2.096). The temperature-limited EPR is 2.16. So, the go-around EPR for operating conditions L-4 is 2.096. According to the notes about the adjustment to the EPR which are located at the top of the Figure 4-28, two engines wing anti-ice on correction is -0.04. Therefore, the go-around EPR setting for operating conditions L-4 is 2.056 (2.096- 0.04 = 2.056).
SECTION F MISCELLANEOUS PERFORMANCE At ftrst, we should understand two definitions of speed. Vc- design cruising speed. VMoiMMo -
ma-ximum operating limit speed.
The Boeing 737 holding table in Figure 4-31 shows the holding EPR, indicated airspeed and fuel flow per engine for various weights and altitudes. You will need to interpolate for conditions between listed weights and altitudes. Assume a Boeing 737 is holing at 34 000 feet at a weight of 112 500 pounds. What is the EPR, IAS and fuel flow required? This problem will require interpolation both between altitudes and weights. Let's do the steps for EPR first. A. Since the weight of 112 500 pounds is exactly halfway between two table listed weights, it is easiest to start by determining the required EPR at each of the two nearest altitudes. At 35 000 feet, the EPR for a 115 000-pound airplane is 2.13, and for a 110 000-pound airplane it is 2.07. Add those two values and divide by 2. The EPR is 2.10. That means the EPR for a 112 500 pound aircraft at 35 000 feet is 2.10. The same calculation for 30 000 feet yields an EPR of 1.84. B. Since the altitude given (34 000 feet) is not halfway between the two table values, it is necessary to calculate the amount the EPR changes per 1 000 feet of altitude. Detennine the difference between the EPR values at each altitude (2.1 0 - 1.84 = 0.26), then divide that number by 5 (0.26/5 = 0.052). C. The EPR variation per 1 000 feet is 0.052, and the EPR decreases as altitude decreases. To determine the EPR for 34 000 feet, subtract 0.052 from the EPR for 35 000 feet (2.10- 0.052 = 2.048). Similar interpolations give a holding speed of 231 knots and a fuel flow per engine of 2 790 powtds per hour. 103
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Using the data from operating conditions 0-2 (see Figure 4-32), the method to find out the recommend lAS, EPR settings and the approximate fuel consumed for holding is similar to the steps described before. Refer to Figures 4-31 and 4-32, interpolation is required for FL230 and 93 000 pounds. At FL 250, the EPR value for 93 000 is 1.56. At FL200, the EPR value for 93 000 is 1.44. Interpolation for FL230 results in an EPR value of 1.51. At FL250, the lAS for 93 000 is 210 knots. At FL200, the lAS for 93 000 is 210 knots. Interpolating for FL230 results in an lAS value of
IOPERATING CONOIT!ONS ALTITU[)E WEIGn'T (X1 000)
ENGINES OPERATING HOLf)lNG TIME (MIN) Figure 4-32
104
0-1
0-2
0-3
0-4
0-5
31.G'O
23,000
17,000
8,000
4 000
102
93
104
113
109
2
2
2
2
2
20
40
35
IG
25
B737 Holding Operating Conditions
: 10 knots. At FL250, the fuel flow per engine for 93 000 is 2 228 LBIHOUR At FL200, the fuel :iow per engine for 93 000 is 2 278 LB/HOUR. Interpolating for FL230 results in a fuel flow per engine value of 2 248 LB/HOUR. According to the conditions 0-2, two engines working for 40 minutes will consume fuel2 997 LB (2 248x2/60x40 = 2 997). Certain questions are "what is the fuel burned in a particular time?" This is a fuel bum problem identical to those covered in the flight logs section. Remember that the fuel flow rates are given per engine. The Boeing 737 (see Figure 4-31) and the Airbus 320 are both twin-engine airplanes. An encounter with strong turbulence can result in structural damage to an aircraft, or inadvertent stalL The sudden changes in wind direction and speed can result in very rapid changes in an aircraft's angle of attack. A sudden increase in angle of attack will cause the airplane to accelerate upward, increasing both the load factor and the stalling speed. When an airplane flying at a high speed with a low angle of attack suddenly encounters a vertical current of air moving upward, the relative wind changes in an upward direction as it meets the airfoil. This increases the angle of attack. A downward gust would have the effect of decreasing the angle of attack. For any combination of weight and altitude there will be a recommended "rough air, speed that provides the best protection from stalls and from the possibility of overstressing the aircraft. When clear air turbulence has been reported in the area, a pilot should adjust the speed to fly at the recommended rough air speed upon encountering the first ripple of turbulence, since the intensity of such turbulence may build up rapidly. Nonnally the speed should be slowed. In this case, neither extending flaps nor extending gear is right action. Use of flaps increases the camber of the wing and angle of attack, but does not decrease the amount of wing loading. Furthermore, extending the gear would increase the drag, but would not change the stability of the airplane. In severe turbulence, it may be impossible to maintain a constant airspeed or altitude. Any attempt to maintain constant airspeed and altitude may overstress the aircraft. If this happens, the pilot should set the power to that which would maintain the desired airspeed and maintain a level flight attitude, accepting large variations in airspeed and altitude. Due to the inaccuracy of the EPR gauges in turbulent air, some aircraft use an N1 (low pressure rotor speed) power setting to maintain thrust. The turbulent air penetration table in Figure 4-33 shows the N 1 power setting for various weights and altitudes. For example, the power setting for a 110 000-pound ai:rplane at 30 000 feet is 82.4%. This RPM (rotation per minute) may have to be adjusted for temperature. For example, at 30 000 feet, the RPM must be changed 1.6% for every 10 ·c deviation from ISA (add for temperatures above ISA and subtract for temperatures below ISA). The ISA TAT (total air temperature) is listed for each altitude. Assume an actual TAT of -8 ·c. This is 15° warmer than standard and would require adding 2.4% to the table value. Using the data from operating conditions Q-3 (refer to Figures 4-33 and 4-34), the table value of the turbulent air penetration N 1 power setting for a 90 000-pound airplane at 35 000 feet is 81.0%. Since the actual TAT is - 16 "C, it is 20 ·c warmer than standard and would require adding 3.2% to 105
the table value. So the corrected N 1 is 84.2%.
TURBULENT AIR PENETRATION OROSS WEIGHT· 1000 LB
TARGET SPECO PRCSS 1\U 1000 FT lAS/MACH
2601 70
%Nt ADJUSTMENT ISA PER 10 "C VARIATION '10 eo 90 100 110 TAT FROM TABLE TA'r COLDER· APPROXIMATE POWER SETTING -~c WAHMEH + ·%N1 RPM
35
77.1
79.0
81.0
83.4
-36
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30
77.2
7B.2
7'3.4
81.1 82.4
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25
76.7
77.5
78.3
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/4.7
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76.1
77.0 77.9
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72.7
73.5
74.2 74.8 75.7
1
1.2
10
70.5
71.3
72.1
9
1.9
72.9 73.9
Figure 4-33 B737 Turbulent Air Penetration
OPERATING CONDITIONS
Q-1
Q-2
Q-.3
Q-4
Q-5
WEIGHT (X1000)
110
70
90
80
100
PRESSURE ALTfTUDE
30,000
25,000
35,000
20,000
10,000
TOTAL AlA TEMP (TA1)
-s •c
-2s·c
-16 •c
·c
-6"C
+4
Figure 4-34 B737 Turbulent Air RPM Operating Conditions
The tables in Figure 4-35 are used to compute the time, fuel and distance required to descend from cruise altitude. There are four different tables representing different speed schedules in the descent. The table at the top left is used if planning to descend at Mach 0.80 until intercepting and lAS of 250 knots. The table at the bottom right is for a descent at Mach 0.80 until intercepting 350 knots and holding that until 10 000 feet and then slowing to 250 knots. Be sure to use the correct table for the planned schedules. For example: Using a descent schedule of 0.80 M/250 KIAS (Knots Indicated Airspeed), if descending from FL370 at a weight of 130 000 pounds, the required time is 26 minutes, the fuel bum is 1 570 pounds and the required distance in nautical air miles (NAM) is 125.5. According to operating conditions S-5 (refer to Figures 4-35 and 4-36), using the descent schedule of 0.80M/320/250KIAS, if descending from FL330 at a weight of 125 000 pounds, the required time is 20 minutes, the fuel bum is 1 420 LB, and the required distance in nautical air miles (NAM) is 97 miles (the interpolation is necessary, the method is similar to the ones discussed before). 106
l"·r
.80M/250 KIAS -·- -
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AT lAN!liNCi Wf"itlT~----,
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LEVEL
410 3&0
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410 390
3ill
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ss 60 46
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NOTE FUEL FOR A STRAIGHT-IN APPROACH IS INCI.LIDED
Figure 4-35 Descent Performance Chart
OPERATING CONDITIONS
$-1
5-2
S-3
S-4
S-5 ~
FLIGHT LEVEL
370
350
410
390
330
LANDING WEIGHT (X1000)
130
150
135
155
125
.80M' 250
.80MI
.80MI
2801250
320/250
.80MI 35Ql250
320/250
DESCENT TYPE
.aorvv
Figure 4-36 Des(:ent Performance Operating Conditions
107
SECTION G
ENGINE-OUT PROCEDURES
In this section, the following three speeds are important for us to understand engine-out procedures.
minimum control speed with the critical engine inoperative. VxsE - best single engine angle-of-climb speed. VysE - best single engine rate-of-climb speed. When an engine fails in flight, the effect on aircraft performance is drastic. For example, the loss of one engine on a two-engine aircraft will result in a loss of climb performance in excess of 50%. Climb performance is determined by the amount of power available in excess of that required for level flight The one remaining engine must provide all of the power required for level flight. It may be able to develop little or no excess power that would allow for a climb. When an engine fails in cruise flight, the pilot should slow the aircraft to its best single-engine rate-of-climb speed (VvsE) and apply maximum continuous power on the remaining engine. The airplane may or may not be able to climb. If it cannot climb at the present altitude, at least it will descend at the minimum possible rate of sink and level off at its maximum engine-out altitude. It may be necessary to dump fuel to improve the altitude capability of the aircraft. If an aircraft is not capable of maintaining altitude with an engine inoperative under existing circumstances, the airspeed should be maintained within ±5 knots of the engine-out best rate--of-climb speed (VysE), in order to conserve altitude as long as possible to reach a suitable landing area A multi-engine airplane should never be flown below its minimum control speed (VMe)· If it is below VMe and an engine failure occurs, it may be impossible to maintain directional control with the other engine operating at full power. VMc will vary with the aircraft's center of gravity location. VMe will be the highest with the CG at its most rearward-allowed position because a rearward CG decreases rudder effectiveness and increases VMC· A commercial operator of large aircraft may conduct a ferry flight of a four-engine airplane or a turbine-engine-powered, three-engine airplane with one engine inoperative, to a base for the purpose of repairing the engine. Several restrictions apply to such flights. These include: A. The airplane model must have been test flown to show that such an operation is safe. B. The operator's approved airplane flight manual must contain procedures and performance data, which allow for the safe operation of such a flight C. The operation weight of the aircraft must be limited to the minimum required for flight plus any required reserve fuel. D. Take-offs are usually limited to dry runways. E. The computed take-off performance must be within acceptable limits (this will vary depending on the type of aircraft). F. The initial climb cannot be over thickly-populated areas. VMc -
108
G Only required flight crewmembers may be on the aircraft.
H. Weather conditions at the take-off and destination airports must be VFR. The table in Figure 4-37 shows the time required to dump to a given fuel weight. The column at the left edge of the table is the initial fuel weight and the row at the top of the table is the ending fuel weight. The intersection of any of those weights is the time requ ired to dump from the beginning weight to the ending weight. INITIAL
FUEL WEIGHT
1000 LB
ENDING FUEL WEIGHT- 1000 L B
r1o_14:1a
22 ~26- 3~ r34'3_: ~~~46 so
27i~ 2~ ~Z2_ 20.18
54 .58 ,62.64 ,70
70
' 28 .
66
62
26 ,25 123 21.20 18 16 15. 13 .12 ,10_ 8 23 23 20 1s 11 1s 13 11 10 a 1 s
58
21
54
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so 46
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7
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FUEL JETTISON
'"""'T.
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10
Figure 4-37 Fuel Dump Time
For example, refer to Figure 4-37, how many minutes of dump time is required to reach an aircraft weight of 144 500 pounds given an initial aircraft weight of 180 500 pounds and a zero fuel weight of 125 500 pounds? A. Determine the initial fuel weight by subtracting the zero fuel weight from the initial aircraft weight: 180 500-125 500 =55 000 pounds. B. Determine the ending fuel load by subtracting the zero fuel weight from the ending aircraft weight: 144 500-125 500 = 19 000 pounds. C. From the table, determine the fuel dump time to go from SS 000 pounds to 19 000 pounds. Interpolate as necessary: Dump time= 15.25 minutes. The tables in Figure 4-38 are used to determine the maximum altitude a Boeing 737 can :naintain with one of its engines inoperative. The engine bleed configuration determines which of ~e three
tables is to be used. The upper table is for all anti-ice off, the middle is for engine anti-ice 109
only, and the lower is for when both engine and wing anti-ice are in use. Once the correct table has been selected, find the aircraft weight at the left-hand side and follow that row across to the appropriate ISA temperature. The only possible adjustment to the table value for the level-off altitude is covered by the note at the bottom of the figure. The note allows an increase of 800 feet in the level-off altitude if the air conditioning is off and the aircraft is below 17 000 feet.
ENGINE An
OFf
-----
,--------------·------.------------
ISA DEY · c
MIOSS WEIOHT 100f• lB
-
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AT ENOINE FAILURr
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NOTE:
WHEN ENGINE BLEED FOR AIR CONDITIONING IS on: OElOW 17.000 FT., INCAI:ASE LEVEL-Off ALTITUDE 8Y 800 FT.
Figure 4-38 Drift-Down Performance Chart
Assume the aircraft weights 100 000 pounds at the time of its engine failure, and the engine anti-ice is on. If the temperature is ISA, the level-off altitude is 19 400 feet. Even if the air conditioning were off, it would have no effect since the level-off is above 17 000 feet.
110
Using the data from operating conditions D-5 (refer to Figures 4-38 and 4-39) is another example. Assume the aircraft weighs 120 000 pounds at the time of its engine failure. If the temperature is ISA + 20° , the level-off altitude is 8 800 feet When engine bleed-air for air conditioning is off below 17 000 feet, increase level-off altitude by 800 feet. Therefore, the level-ofi altitude is 9 600 feet (8 800 + 800). OPERATING CONDITIONS
D-1
D-2
D-3
0-4
0-5
WT AT ENG FAIL (X1000)
100
110
90
80
120
ENGINE ANTI-ICE
ON
OFF
ON
ON
ON
OFF
OFF
ON
ON
OFF
ISA TEMPERATURE
JSA
+10~
-10"
-10"
+:'.O•
AIR CONDITIONING
OFF
OFF
OFF
OFF
OFF
WING ANTI-ICE
Figure 4-39 B737 Drift-Down Operating Conditions
SECTION H FLIGHT PLANNING GRAPHS AND TABLES Aircraft manufacturers publish flight planning graphs of tables that enable the flight crews to quickly estimate the time and fuel required to fly certain trips. These table or graphs allow adjustments for aircraft weight, wind, altitude, cruise speed and other variables. The graph in Figure 4-40 is used to determine the time and fuel required for a planned flight It allows for trip distance, wind, flight altitude, landing weight and temperature. This example shows the solution for operating condition X-1 (see Figure 4-41). Start at the bottom of the graph in Figure 4-40 with the trip distance (2 000 NM) and draw a vertical line to the reference line representing a zero knot wind component. Condition X -1 states that there is a 50-knot tailwind component. From the reference line follow the curved diagonal line back to the - 50-knot line. This will result in an equivalent trip distance of 1 800 NM. From there, draw a vertical line through both sets of diagonal lines representing cruise altitude. To determine the trip time, find the point of intersection between the vertical line and the diagonal in the upper set which represents the cruise altitude (27 000 feet). From there draw a horizontal line to the reference line representing 0° deviation from ISA. Since the temperature in condition X-1 is ISA + 10°, from the reference line parallel the diagonals down and to the left to the ISA + 10° line. From there draw a horizontal line to the trip time (3 hours, 55 minutes). To determine the trip fuel, fmd the point of intersection (on the lower set of altitude diagonals) between the vertical line drawn earlier and the diagonal line used for the cruise altitude. From there, draw a horizontal line, the reference line representing a landing weight of 65 000 pounds. Since the
111
landing weight in condition X-1 is 70 000 pounds, parallel the diagonal lines up and to the right until meeting the vertical 70 000-pound line. From there, draw a horizontal line to the trip fuel (26 000 pounds).
Figure 4-40 B 737 Flight Planning 0.78 Mach Indicated
X-1!
X-2
)(..3
X-4
X-5
l
2.'00
l.~jOO
2.800
1 .200
WIND COMPONENT (KTS)
:.oTWI
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CAU:SS PRESS ALTITUOE
27.000
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29.000
37000
.. jQ•
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+10"
65
90
OPERA TrNG CONOIT!ONS
D ISTANCE (NM)
2.000
ISA TEMPERATURE LANDINC1 WEIGHT {X 1000~
701
;
I
75
20 (',()0 +?.0~
7!>
~
Figu~ 4-41
112
Flight Planning at 0.78 Mach Cruise
I
-- r -
The table in Figure 4-42 shows the time and fuel required for trips of various distances. For example, a trip of 340 NM requires 55 minutes and consumes 5 550 pounds of fuel. A wind will change both the time and fuel required for a given flight The notes at the bottom of the table explain the correction factors. The formulas are: Change in Time= Time x Wmd Component+ TAS and Change in Fuel =Fuel x Wmd Component + TAS ABBREVIATED FLIGHT PLANNING .2801.70 CLIMB .74r.!201340 DESCENT 250 KTS CRUISE. BELOW 10000 FT. 320 KTS CRUISE 10000 THAU 23000 FT. 74 MACH CRUIS E 24000 FT. AND ABOVE OIST. N. MI. ~.,
REC. ALT.
£0
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290 ~UD
310
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450
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- --447
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TIME AllO FUEL CORRECTION FOR WIND TIME a TIME X WIND COMPONENT + TAS FUEL • FUEL X. WINO COMI"ONEN'I > TAS EXAMPLE: OIST, - 250 STILL .&.IR TIME z ~:!.MIN. STILL AIR FUEL ~ 45(10 LBS. liME " 43 X 20 + 449 " &!JN. WINO COMPONENT- 20 KTS /). FUEL • 4500 X 20 449 200 LBS. ADD fl. TIME AND /J,. FUEL FOR THE HEADWIND; SUSTRACT FOR TAILWIND
!J.
6.
6.
= =
Figure 4-42 Abbreviated Fligbt Planning
Assume a 25-knot tailwind for the conditions above. The formulas are: Change in Time= 55 x (-25) + 438 = -3.1 minutes and Change in Fuel =5 550 x (-25) + 438 = -316.8 pounds
113
The corrected time is 51.9 minutes (55- 3.1), and the corrected fuel is 5 233.2 pounds (5 550 - 316.8). N otice that a tailwind is entered as a negative number because it reduces the required time and fuel. A headwind should be entered as a positive number since it will increase the required time and fuel. The table in Figure 4-43 is used to plan for possible diversion to an alternate airport. For example, in condition L-1 (see Figure 4-44) the alternate is 110 NAM away. It will take 29 minutes to fly there and make an approach. It will also require 3 400 pounds of fuel, which includes an additional 15 minutes of holding fuel.
ALTERNATE PL ANNING CHART (liST
N/IM
!WIM AI I
TIME HIH
20
30
AO
50
60
10
80
90
100
110
?000 1b 2500
3000
.17
4000 '19
6000 22
7000
8000
11000
;23
:25
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2800
?900
~80
289
3000
3)00
286
292
?90
9000 :28 3200 300
10000
2600
5000 '20
160
190
200
210
220
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20000
21000 :43 4400 341
22000
m:.
TAS
OIST. NAM
150
160
170
OPJM AIr
ISOOO 35 :1&0U 319
16000
agoo
36
17000 :38 4000
323
326
330
33.4
280
290
300
310
320
330
340
3~0
?1000 !>3 5150
28000 55 5250 372
28000
29000 53
30000 1;()()
30000 1 .02
31000
:SG
29000 :58
53 SO
!)4~0
S800
1:03 5900
380
5600 385
S/00
371!
388
392
397
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DISl • NAM OI'TM AIT
liME. HIFL
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TAS
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4300 J38
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:!9
130
140
12000 13000 ·32 .~0
IQOOO :33
120
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3400
3500
1600
1700
306
308
312
!liS
230
:>•o
2SO
23000 24000 .46 ~48 <4800 4/00 349 353 360
370
31000 31000 104 105 6050 6150 397 397
260
210
25000 26000
27000
4800 357
<4900 361
5000 365
380
J90
•oo
31000 31000 108 I 07 63!.0 82!>0 3!H 397
31000 1.10
.so
•49
:S2
6500
397
NOTES: 1
Fuel inc;ludu 112 clrmb dtstance en route credit, fuel to cruise remaining distance at LRC schedule 15 minutes holding at alternate, and 800 lbs. for descent.
2. Tim" includes 112 climb distance credit, time to crUise distance shown at LRC schedule nnd 8 minutes lor descent. 15 minutes holding is not Included In time.
Figure 4-43 DC-9 Alternate Planning Chart
OPERATING CONDITIONS WEIGHT (START TO ALT) DISTANCE (NAM) WIND COMPONENT (KTS) HOLDING TIME AT ALT (MIN)
L-1
L-2
L-3
L-4
L-5
85,000
70 ,000
86,000
76,000
82,000
11 0
190
330
50
240
15 HW
40TW
50 HW
20TW
45HW
15
15
15
16
15
Figure 4-44 DC-9 Alternate Planning Operating Conditions
The conditions specify that there is 15 minutes holding at the alternate. Since Note 2 in Figure 4-43 specifically states that 15 minutes holding is not included in the time, then we must add the 15 minutes to the time listed in the alternate planning chart. Wind is not a factor since both figures deal in nautical air miles (NAM), so you should disregard the wind component
114
provided in the operating conditions. 29 + 15 =44 minutes Landing weight may be calculated by subtracting fuel burn from gross weight as follows: 85 000-3 400 = 81 600 lbs
SECTION I TYPICAL FLIGHT LOGS Flight logs are used to accurately plan the time and fuel required for a flight. In the following paragraphs we describe all the steps required to complete a flight log. A. Determine the magnetic courses for each leg and determine the leg distance. B. Apply variations to the winds aloft. C. Determine the temperature in relation to ISA. D. Determine Mach number and convert to TAS. E. Compute ground speed. F. Calculate and record the time for each leg. G Compute fuel flow. H. Compute total fuel. I. Determine the reserve fuel. J. Compute fuel burn to alternate. K. Add the en route, reserve, alternate, and missed approach fuel to find the total fuel required for the flight.
COMPUTATION OF TEMPERATURE AT CRUISE ALTITUDE Temperature is often expressed as a deviation from ISA which is the standard day temperature (i.e., ISA - 2 ·c). This temperature can be computed by the following procedure: A. Compute ISA by multiplying the altitude in thousands of feet times - 2 ·c and then adding 15 ·c. For example: ISAat27 OOOfeet=27 x (-2 ·c)+15 ·c =-39 ·c. B. Apply the deviation from ISA. ISA -2 ·c at 27 000 feet= (- 39 ·c)+ (- 2 ·c)= - 41 ·c.
COMPUTATION OF TRUE AIRSPEED USING MACH NUMBER True airspeed (TAS) can be computed from Mach number and outside air temperature (OAT). Using the CX-2 computer, select "plan Mach#" from the menu, then enter the OAT and the Mach number at the appropriate prompts. A. ln the small window labeled "Airspeed Correction" or "True Airspeed", align the arrow labeled "Mach Number'' with the OAT on the scale adjacent the window. B. Find the Mach number on the inner of the two main scales and then read the TAS opposite it on the outer scale. 11 5
Note: Some "CR"-type mechanical computers have a window in which a Mach index is aligned with a Mach number inside the window. Don't use this scale.lt is designed to use indicated temperature and will give an inaccurate TAS when OAT is used. See the instruction manual of your individual computer for more detailed instructions.
SPECIFIC
RANGE
Specific range is the term used to describe the rate of fuel burn per nautical air mile flown. It is calculated by using TAS and fuel flow only. Wind bas no effect on specific range. To calculate specific range in nautical air miles per 1 000 pounds, use the formula: NAM/1 000 =TAS X 1 000-T PPH TAS should be calculated from the Mach number as in the paragraph above. PPH can be taken directly from the flight log. Refer to Figure 4-45, in block 3 of the flight plan, there is the following entry: B/B747/R. Prefixes in the aircraft type box can be T/ (TCAS equipped), HI (heavy aircraft), or B/ (heavy aircraft and TCAS equipped). Therefore, the prefix "B" here indicates TCAS and heavy. The ''R/'' changed to "II" in February 1999. The "tr' indicates RNAV/Transponder/altitude encoding capability. The suffix II means the aircraft is equipped with LORAN, VORIDME, or INS (RNAV), and transponder with Mode C (altitude encoding capability). Refer to Figure 4-46, in block 3 of the flight plan, the G following MD90/ indicates the aircraft is equipped with GPS/GNSS that has oceanic, en route, and terminal capability. The /G indicates Global Positioning System (GPS)/Global Navigation Satellite System (GNSS) oceanic, en route, and terminal capability. Example l
Refer to Figures 4-47, 4-48, and 4-49, we can find out the ETE from Chicago Midway Airport to Greater Buffalo Inti, the fuel requirements for the flight according to the following steps. To solve this problem, complete the flight log in Figure 4-47, using the information given in the problem: A. Change the w~"'lds aloft ofFL 190 at GU (Gipper) from true to magnetic, using the variation from the flight log (see Figure 4-47). Note: The variation changes with each leg. Winds at GIJ at FL 190 are 230° true at 51 knots. 230° True + 01 o West Variation 231o Magnetic B. Find the distance flown for the leg. In this case it is 19 nautical miles, since the L/0 point is on the GIJ 270° radial at 19 NM. Distance for subsequent legs must be determined by referring to the en route charts (see Figure 4-49). C. Find the ground speed for the leg from L/0 to GIJ using a flight computer: • Wmd direction 231o (calculated in Step A). 116
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DEPARTURE ROUTE DESCRIPTION All aircraft expect rodor vectors to first l!nrovte fix. Expect cleorcnc;e to reque$ted ohitudclflight level ten minute$ alter departure. TAKE-OFF RUNWAYS 22LIR, . IC/R, 13LIC: Climb runway hooding to 1300' before turning on coune. TAKE-OFF RUNWAYS 4l/R: Northbound deporture5 assigned headings 360° (CW) thru 080°, turn right climb on heading I 00° until leaving 2400. Thence via vector ro O$Signed route OME-EQUIPPED AIRCRAFT: Complete initially assigned turn within 4 DttoE of Midway. Maintain 3000' or assigned lawor altitude. Expcd clearance to reqt•ested altitude 10 minutes after depor•ure. NON-DME EQUIPPED AIRCRAFT: Comple1e initially ossigned turn south of DPA R-096, maintain 3000' or a~signed lower altitude. Exped clearance to roque$ted altitude l 0 minutes after departure.
MIDWAY FOUR DEPARTURE (VECTOR) 9~31.2
CHICAGO, IlliNOIS
CHICAGO MIDWAY (MDW)
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• Wrnd speed 51 knots (given on the flight log). • Course 090° (L/0 point is on the GIJ 270° radial). • TAS 160 knots (given in the flight plan in Figure 4-47). Calculated GS is 196.4 knots. D. Compute the time en route for the leg from L/0 to GIJ: • Distance 19 NM (determined in Step B). • Ground speed 196.4 (calculated in Step C). Calculated leg time is 5 minutes, 48 seconds.
E. Since the next question asks for the fuel required for the flight, calculate the fuel burned on this leg. • ETE is: 5:48 (calculated in Step D). • Fuel flow is 61 0 PPH (in note at the bottom of the flight log). Fuel burned is 59.0 pounds. F. Repeat steps for the subsequent legs to fill in the flight log: TO FROM CRS TAS GS NM ETE FUEL 327.0. MDW :19:00* L/0 160 L/0 GIJ 090 196 19 :05:48 59.0 085 160 200 129 :38:58 392.8 GIJ CRL CRL YXU 065 160 219 118 :32:20 328.7 TID 101 :22:18 236.7 YXU 160 215 80 :14:oo· 121.5° TID BUF 30 *(given) 2:12:04 1455.7 G. Since the fuel burned from Chicago Midway Airport to Greater Buffalo Inti has been calculated in Step G (1 455.7 pounds), the fuel requirements are: • Fuel burned: 1 455.7 • Fuel for alternate to ROC: 236.0 • Fuel for reserve: + 532.5 • Fuel requirements: 2 224.2 So, the fuel requirements are 2 224.2 pounds. Furthermore, refer to Figures 4-47,4-48 and 4-49, the method to fmd out theTAS maintained to arrive over CRL VORTAC 42 minutes after level-off should be: A. Detennine the required ground speed using a flight calculator: • Distance flown is 148 NM (distance from L/0 to GIJ to CRL). • Time is 42 minutes (given in the problem). Calculated GS is 211.4 knots. B. Detennine the required TAS: • Wmd direction is 231 magnetic (see Steps A and B of the former question). • Wrnd speed is 51 knots (given in flight log). • Course is 087 (average of the legs). 122
• GS is 211.4 (calculated in Step A). TAS is 172.8 knots. Example2 Refer to Figures 4-50,4-51 , 4-52,4-53,4-54, and 4-55, we can find out the ETE from LAX to PHX at 0.78 Mach, the total fuel required at the speed according to the following steps. To solve this problem, complete the flight log in Figure 4-51 , using the information given in :he problem: A. Change the winds aloft at FL270 from true to magnetic, using the variation from the airport/facility directory entries for the LAX and PHX VORTACs. Winds at IPL at FL270 are 300° true at 43 knots. 300° True - 15° East Variation 285° Magnetic B. Calculate theTAS for Mach 0.78.
• ISA temperature at FL270 is - 39 ·c, i.g., 27 X(- 2 ·c) + 15 ·c. • ISA- 2 ·c = - 41 ·c. Using a flight calculator, determine that Mach 0.78 equal 463.1 knots. C. Find the distance flown for the leg. In this case it is 50 NM. The remarks section of the flight plan notes that the L/0 point is on the OCN 270 radial at 50 NM. The first leg of the IMPERIAL THREE Departure is from there to OCN. Even though only one line is used for the cruise portion of the IMPERIAL 3 departure, each leg of it should be calculated separately for best accuracy. The same is true of the ARLIN 9 Arrival into PHX. D. Find the ground speed for the leg from L/0 to OCN using a flight computer: • Wmd direction 285° (calculated in Step A). • Wmd speed 43 knots (given on the flight log). • Course 090° (L/0 point is on the OCN 270° radial). • TAS 463.1 knots (calculated in Step B). Calculated GS is 504.5 knots. E. Compute the time en route for the leg from L/0 to OCN: • Distance 50 NM (determined in Step C). • Ground speed 504.5 (calculated in Step D). Calculated leg time is 5 minutes, 57 seconds. F. Since the next question asks for the fuel required for the flight, calculate the fuel burned on this leg.
• ETE is: 5:57 (calculated in Step E). • Fuel flow is 9 600 PPH (in note at the bottom of the flight log). Fuel burned is 951.4 pounds. G. Repeat steps for the subsequent legs to fill in the flight log: 123
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129
NM 43 uo uo OCN 090 463.1 504.5 50 083 463.1 502.7 42 OCN JLJ JLI KUMBA 115 463.1 505.4 35 KUMBA 078 463.1 501.0 27 IPL IPL BZA 074 463.1 499.4 46 BZA Mohaklnt 075 463.1 499.0 32 067 463.1 494.7 15 Mohak TIP TIP HYDRR 035 463.1 473.9 42 HYDRR ARLIN 076 463.1 499.0 19 ARLIN PHX *(given) FROM LAX
TO
CRS
TAS
GS
ETE FUEL :19:00* 4 sto.o· :05:57 :05:01
951.4 802.1
:04:09 :03:14
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:05:32 :03:51 :01:49 :05:19
517.4 885.3 615.6 290.7 850.7
:02:17 365.3 • :12:00 1 140.0* 1:08:09 11 593.3
In this question, the regulation-required fuel must be calculated using the summary box at the bottom of the flight plan: A. Compute the fuel required to fly the flight: • Fuel required is 11 593.3 pounds (see flight plan before). B. Compute the required reserve fuel (see Step F of the former question): • Time required is 45 minutes. • Fuel flow is 9 250 PPH (given at the bottom of flight plan in Figure 4-51). Reserve fuel is 6 937.5 pounds. C. Determine ETE to alternate: • ETE to alternate is 26 minutes (given in the flight log). D. Compute fuel bum to alternate (see Step F of the former question): • Time to alternate is :26:00 (from Step C). • Fuel flow is 9 250 PPH (given in flight log). Fuel burn to alternate is 4 008.3 pounds. E. Add the totals ofStepsA throughD:
FUEL En route 11 593.3 Reserve 6 937.5 Alternate + 4 008.3 Total 22 539.1 Furthermore, refer to Figures 4-51 , 4-52, 4-53, 4-54 and 4-55, the specific range in nautical miles per 1 000 pounds of fuel from level-off to the ARLIN Intersection using 0.78 Mach should be calculated as the following method: NAM/1 000 is calculated by multiplying TAS times 1 000 and dividing the answer by the fuel 130
::ow. TAS is 463.1 (calculated in Step B of the former question to find out ETE). Fuel flow is 9 600 PPH (given in the flight log). NAM/1 000 = 48.2. Example3 Refer to Figures 4-51, 4-52, 4-53, and 4-55. The steps how to fmd the approximated indicated ~Iach maintained to arrive over the BZA VORTAC 6 minutes after passing IPL VORTAC are iiscussed as follows: A. Determine the required GS: • Distance is 46 NM (see Figure 4-53). • Time is 6 minutes (given in the question). GS = 460 knots. B. Determine the required TAS: • Wmd direction is 287° magnetic (300° true from flight log, less 13° CilSt variation). • Wmd speed is 43 knots (given in flight log). • Course is 074° (see Figure 4-53). • GS is 460 knots (calculated in Step A). Required TAS = 424.6 knots. C. Calculate the temperature: • ISA temperature at FL270 is- 39·c, ig., 27 x (- 2·c) + 15·c. • ISA - 2 ·c =- 4t •c . D. Calculate the required Mach number: • TAS is 424.6 knots (calculated in Step B). • Temperature is - 41 ·c (calculated in Step C). Required Mach number is 0.715.
131
CHAPTER 5 WEIGHT AND BALANCE SECTION A
INTRODUCTION
The correct loading of an airplane is one of the essential elements in establishing the safety for aircraft operations. For this reason, the determination of weight and balance lin the approval of loading procedures are an important part of the airworthiness function speo regulations. Regulations specify the requirement for establishing each aircraft's weight at of initial registration, and the requirement for a load data sheet and a loading system. The system is the approved method that operating crews must use on each flight to establishi weight and balance.
OVERWEIGHT OPERATIONS Apart from the fact that you would be contravening the regulations, if you operate an in excess of the structural limits, it will inevitably downgrade the strength of the aircraft. C< overweight operations could also accelerate the onset of metal fatigue induced structural fail Aircraft loaded in excess of the maximum weight permitted by runway, altitude or tern limitations cannot be expected to perform as required by the certification standard. Accelera be slowed during the take-off roll with the result that more take-off run will be require lift-off the aircraft will climb at a slower rate. In the event of an engine failure, an aircraft be able to climb at all in the second segment. Basically, overloading erodes the safety provided by the certification standard, particularly in the case of an emergency, such ru failure. In the cruise, operations at weights more than permitted by performance standards I'l slower cruise speed for a given engine power setting. Fuel consumption will also be higher. Finally, although an overweight landing may appear to be less of a problem, there is al' possibility oftyres bursting, brakes failing and over-running the end of the runway.
BALANCE LIMITATIONS Calculation of aircraft balance will determine whether the center of gravity position i permitted limits. This ensures that the aircraft will remain fully controllable throughout tb Adverse balance situations can cause marked deterioration in longitudinal stability and e< 132
the point where an aircraft may become uncontrollable. For example, if the CG is located too far forward, it may be difficult to raise the nose on take-off. An aircraft flown outside the approved weight and balance limits is being operated in an area where compliance with the required levels of airworthiness has not been demonstrated. Such operations clearly put the safety of both aircraft and occupants at risk.
SECTION B WEIGHT AND BALANCE PRINCIPLE W EI GHT TERMINOLOGY There are some differences in weight definitions for different types of aircraft. For a Boeing 727-type aircraft, the weight and balance calculation is usual to start with the basic operating weight (BOW). It is defined as the basic empty weight of the aircraft plus the weight of the required crew, their baggage and other standard items such as meals and potable water. However basic weight does not include usable fuel or payload. Payload, as the name implied, is the weight that is carried which can generate revenue. In some sense, BOW is just the same as the dry operating weight (DOW) defined for B737 and A320 aircraft below. For A320 aircraft, basic weight is defined as the aircraft weight without any load. This means a weight not including crewmembers, pantry load, fuel load and traffic load but including the commercial arrangement of the corresponding version and the unusable fuel. But for Boeing 737, the basic weight of the aircraft is the empty weight plus items of an operational nature otherwise. For both of them, dry operating weight (DOW), usually as the start of the aircraft weight calculation is the weight of the aircraft in operating configuration. It is obtained by addition of the basic weight, crewmembers and pantry load for A320. As for B737, DOW is also referred to as adjusted basic weight, allows for these variations such as the type and length of flight, and will have different values for the same aircraft conducting different operations. Take-off fuel is the weight of the inboard fuel onboard at take-off. Operating weight is defmed as the weight obtained by addition of the dry operating weight and the take-off fuel. Total traffic load is the weight of the payload including cargo loads, passengers and passengers' bags. Zero fuel weight is obtained by addition of the total traffic load and the dry operating weight Take-off weight is equal to the addition of the zero fuel weight and take-off fuel. Trip fuel is the weight of the fuel necessary to cover the normal leg without reserves. At last, the landing weight, as the name implied, is the weight at landing. It is equal to take-off weight minus trip fuel. Following summary should help you remember how various weights are calculated: Dry Operating Weight (DOW) +Payload (Total Traffic Load) = Zero Fuel Weight +Take-offFuel 133
= =
Take-off Weight - Planned fuel burn to destination (Trip Fuel) Landing Weight
Dry Operating Weight (DOW)
+ Take-off Fuel
=
Operating Weight
CENTER OF GRAVITY The center of gravity of an aircraft is the point about which the aircraft would balance if it were possible to suspend it at that point The total weight can be assumed to be concentrated at, and act through the CG, as shown in Figure 5-l.
-
I
""
Weight
Figure S-1 Center of Gravity
For most aircraft, the CG position will change whenever the weight of the aircraft changes or when items are moved within an aircraft. The most common reason for a changing CG position during a flight is the reducing weight of fuel as the flight progresses. For most modem swept-wing transports with a large proportion of fuel stored in the wings, reducing fuel contents will concentrate the remaining fuel toward the wing root. This result in a forward movement of the CG as fuel is consumed. To assist in deciding where everything on and in an aircraft is positioned, and what effect each item might have on the CG position, a reference datum is chosen arbitrarily at some point along the length of the aircraft. The relative position of the various items to be considered is measured from this datum. The horizontal distance from the datum to any component of the airplane or to any object located within the airplane is called the arm, or station. In some aircraft, the datum is located ahead of aircraft. Since there can be no components ahead of the datum plane, all items used to compute the weight and balance of such an airplane will have positive values and usually are referred to as inches aft the datum.
MOMENT A moment is the turning effect of a force about a point, and is found by multiplying the force 134
-. :t:S arm. By totaling the weights and
moments of all components and objects carried, the point ::;!re a loaded airplane would balance on an imaginary fulcrum can be determined. This is the
1.:...-:>lane's CG.
''EAN AERODYNAMIC CHORD The center of gravity of a properly loaded airplane must always fall somewhere along the =ean aerodynamic chord (MAC). The CG is often expressed as a percent ofMAC. If the CG were :: the leading edge of MAC (LEMAC), it would be at 0% of MAC. If it were at the trailing edge of .f.-\C (TEMAC), it would be at 100% of MAC. See figure 5-2. In the design and certification stage :::e manufacturer will specify the full length of the MAC, and the actual position of the ~C .eading edge (LEMAC) relative to the reference datum. Oalum
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Figure 5-2 Center of Gravity Terms
In loading systems, a percentage MAC is generally used to defme the fmal computed aircraft
CG position, and moment index units (which will be described later) are used to calculate the variation in CG position as fuel and payload are added.
CENTER OF GRAVITY ENVELOPE An aircraft will have certain extreme center of gravity limits which defme the furthest points forward and aft of the datum being used. However, quite often these limits vary as the weight of the aircraft changes. A diagram which shows limiting CG position for various weights is called a CG envelope, and a typical example is shown in Figure 5-3. Such variations of CG position with weight may be for structural reasons or for purely balance purposes. It is important to ensure that the CG position for a given weight falls within the envelope and not merely between the fore and aft limits (known as the CG range). In the CG envelope shown in Figure 5-3, the forward and aft limits of the CG vary from 18.4% MAC and 33.0% MAC respectively, at a gross weight of 10 000 kg with a CG position of 20% MAC, and then the CG position is within the envelope (position A). However, if the aircraft is loaded so that at a weight of 18 000 kg, it has a CG position of 20.5% MAC, then the CG position is just outside the forward limit of the CG envelope (position B). A CG position of 32% MAC at a 135
weight of20 000 kg is outside the aft limit of the envelope (position C). 24.7
30.5
22
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i ;
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18
18
20
22
24
28
28
30
32
34
38
Location of CG u % MAC
Figure 5-3 A Typical of CG Envelope
Clearly, it is not only important to calculate the CG position but also to compare it with the CG range. Both weight and CG position must be used together to ensure aircraft loading is within limits. This is particularly important in large transport category aircraft where the range of CG positions and weights vary considerably.
LOADING ZONE With very large aircraft, numerous combinations of passenger seating positions are possible when passenger numbers are less than the number of seats (i.e. the aircraft is not full). In such situations it would obviously be very time consuming to calculate CG position by plotting each seat position with its weight on a complex loading sheet. Loading zones are an approved method of calculation CG position by dividing the aircraft cabin into zones and simply adding up the weight within each zone. This zone weight is then considered to act through a single position for that zone, regardless of the actual zone weight. Despite of the flexibility that loading zones provide, it is nevertheless very important to control the center of gravity position by ensuring that zones are loaded evenly, or within the limits permitted by the CG range of a particular aircraft. The seat allocating system of an airline is primarily designed for this purpose. 136
SECTION C CENTER OF GRAVITY COMPUTATION AND STABILIZER TRIM SETTING In this section, two computation methods will be introduced, one for B727 and the other for
B737-300 and A320.
8727 Center of Gravity Computation For most early aircraft like B727, the first step in the solution weight and balance problem is the calculation of the total weight of the aircraft (gross weight) and the total moment. Of course, the actual moment is often converted to a moment index for the purpose of simplifying the computation. The moment index is the actual moment divided by 1 000 for a Boeing 727-type aircraft in airline transport pilot (ATP) test. To detennine the total weight and moment index, a separate weight and moment must be calculated for the BOW, the passenger loads in the forward and aft passenger compartments, the cargo loads in the forward and aft cargo compartments, and the fuel loads in fuel tanks l, 2, and 3. We show the solution process with the following example. A 8727 has a basic operating weight at 105 500 pounds and the basic operating index (moment/1 000) is 92 837. See Figure 5-4. There are 18 passengers in the forward compartment (FWD Comp) and 95 passengers in the aft compartment (AFT Comp). The weight of the passengers can be detennined by use of the passenger loading table in the upper left-hand comer of Figure 5-5. Since neither 18 passengers for the forward compartment nor 95 passengers for the aft compartment AIRPLANE DATUM CONSTANTS (IIAC l.E ol Bas.c
180 9 Inches 860 5 l'lclles 92.837 0 1.000-
~AC
Oo~
lorl.ox
OPERATING LIMITATIONS Ma xtnum Ta!(eofl S'ope Max:num Taxeoll 1 Landing Crosswind Component Ma1:m\im Taktilof! I L:~r.ding Ta ilwmd Component
•2~o
32 knots 12 knols
WEIGHT LIMITATIONS 105.500 pounds
WoJtgh1 'ii!ax•nutn Zero Fuel Watglll Mallimutn Taxi W11l,;n
B.t&IC ol)"laltng
M;.;(imum Takeoil Weight (Brake Release} Maxurtulll '" fi1oht Wetght {Flaps .1Q) (Flaps .:o) Walomum l<~nd "9 Wt>•g~,t {Cfnp:. 301 ("'lap~ 40)
Figure 5-4
:38.500 pounds 185.700 pound s f 84.700 pount!s · 55. 500 poun•i:> '~4
000
UO•JOJ5
155 000 po1.1n.Js 143 000 pounds
8727-Table of Weights and Limits
137
are listed in the table, the weight must be calculated by multiplying the number of passengers times the average weight per passenger. A quick examination of the table reveals that the average passenger weight is 170 pounds. The weights are: FWD Comp = 18 x 170 = 3 060 lbs AFT Comp =95 x 170 = 16 150 lbs The Moment Index (MOM/1 000) is calculated by using the formula: Weight x Arm/1 000 =MOM/I 000
CARGO LOADING TABLE
PASSENGER LOADING TABLE
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.,
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2.550
2r. n
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20
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FUEL LOADING TABLE TANKS 1 & 3 (EACH) 1'1019/tt Arm
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The arms for the passenger compartments are listed at each top of the compartment loadmg tables after the words "Forward Compartment Centroid" and "Aft Compartment Centroid". The 138
az:n for the forward compartment is 582.0 inches, and the aft compartment arm is 1 028.0 inches. :he easiest way to apply the 1 000-reduction factor is to move the decimal on the arm three places -J the left (i.e., 582.0"/1 000 = 0.582). In the example used, the moment/! 000 for the forward and m passengers compartments (rounded to the nearest whole number) are: FWD Comp Moment/1 000 = 3 060 x 0.582 = 1 781 AFT Comp Moment/1 000 = 16 150 x 1.028 = 16 602 The weights for the forward and aft cargo holds are stated as follows: there is 1 500 pounds in :..1e forward hold and 2 500 pounds in the aft hold. The moment/! 000 can be determined from the :abies in the upper right-hand comer of Figure 5-5. For example, the moment/1 000 for 1 500 pounds in the forward cargo hold is determined by adding the moment/1 000 for 1 000 pounds (680) and the moment/1 000 for 500 pounds (340). If necessary, the moment/! 000 can also be determined by multiplying weight times arm (divided by 1 000). The moment/] 000 for the cargo holds are: FWD Hold = 1 020 AFT Hold= 2 915 Fuel tanks 1 and 3 are the wing tanks and are always loaded with the same weight of fuel. They will always have the moment/1 000 as well. The number 2 tank is the center fuselage tank and will often have a fuel weight different from tanks 1 and 3. It will always have a different moment/1 000. In the example, the fuel load in tanks 1 and 3 is 10 500 pounds each and that the load in tank 2 is 28 000 pounds. The moment/1 000 for each is determined from the table in the bottom portion of Figure 5-5. The moment/! 000 can be calculated, if necessary, by multiplying weight times arm (divided by 1 000). Notice that the arm varies with the fuel load in each tank. The moment/! 000 for tanks 1, 2 and 3 respectively is: Moment/1 000 = 10 451 Moment/1 000 = 10 451 Moment/1 000 = 25 589 The total weight and total moment/1 000 is the sum of all the items discussed above. The total weight and moment/1 000 are: BOW 18PAXFWD 95PAXAFT FWD Cargo AFT Cargo Fuel Tank 1 Fuel Tank 3 Fuel Tank2
Weight 105 500 3 060 16 150 1500 2 500 10 500 10 500 28 000
Moment/1 000 92 837 1 781 16 602 1020 2915 10 451 10451 25 589
Total 177 710 161 646 The center of gravity in inches aft of the datum line can be determined by using the formula: 139
CG =Total Moment I Total Weight Since these questions use a moment index instead of moment, it is necessary to modify thi~ fonnula by multiplying the total moment/total weight by the reduction factor (1 000). The fonnul' then be<:omes: CG = (Total Moment Index I Total Weight) x 1 000 Using the weight and moment/1 000 we calculated the above: CG = {161 646/177 710) x 1 000 = 909.6 inches The center of gravity of a properly loaded airplane must always fall somewhere along the mean aerodynamic chord (MAC). The CG is often expressed as a percent of MAC. The CG's percent ofMAC is calculated by: A. Determine the CG in inches aft of LBMAC b~ 'i>U.b~ctiug the distance datum to LEMAC from the CG in inches aft of Datum. The distance from datum to LEMAC is given ir Figure 5-4 as 860.5 inches. This is used for all calculations of percent of MAC for tb( B727. The CG in inches aft of datum is calculated in the previous paragraph. Using thos( numbers: CG (inches aft ofLEMAC) = 909.6- 860.5 = 49.1 inches B. Detennine the CG in percent of MAC by dividing the CG in inches aft ofLEMAC by the length of MAC. The length ofMAC is the distance in inches from LEMAC to TEMAC. !1 is given in Figure 5-4 and is 180.9 inches. The fonnula is: CG (%of MAC)= (CG in inches aft ofLEMAC I MAC) x 100% Using the numbers from the above: CG(% ofMAC)=(49.1 I 180.9) x 100%=27.1%
----f' u U~ITS ~~n~~;.~:
Finally, we flnd that the CG is located 909.6 incht-s aft of datum or at 27.1% MAC.
Stabilizer Trim Setting The correct horizontal stabilizer trim setting is very critical for proper take-off performance of jet aircraft. The main determinants are the CG location and possibly the flap setting. Some aircraft, such as the DC-9, have their stabilizer trim indicators calibrated in percent of MAC, so it is necessary to calculate the CG to know the trim setting. Other aircraft (such as the B737 and B727) have their trim indicators marked off in units of nose up trim. In such cases it is necessary to refer to the trim table to determine the proper setting for a given CG The stab trim setting table at the left side of Figure 5-6 is used to determine the take-off trim setting for a 8727. Flap setting and CG location in 140
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oercent of MAC are used to determine the setting. For example, if the CG is at 28% of MAC and the flaps are set at 15° the stab trim setting is 4-1/2 units ANU (Airplane Nose Up).
8737-300 The purpose of the B737 and A320 load sheet and balance and trim chart are to provide an orderly method of determining the aircraft weight at certain critical stages (zero fuel, taxi, brake release and landing); and at the same time determining the corresponding CG position for each stage. Completion of the sheet also allows the aircraft horizontal stabilizer setting for the particular take-off flap setting to be determined. The following example uses B737-300 (148 version) as sample aircraft. The load conditions are: Load distribution: FWD Hold 1 (baggage 1 500 kg, cargo 400 kg, mail 95 kg) 4 400 pounds or 1 995 kg AFT Hold 4 (baggage 1 500 kg, cargo 300 kg, mail 195 kg) 4 400 pounds or 1 995 kg 40 passengers in FWD Passenger Compartment (6 600 pounds or 2 994 kg) 50 passengers in MID Passenger Compartment (8 250 pounds or 3 742 kg) 48 passengers in AFT Passenger Compartment (7 920 pounds or 3 592 kg) Fuel: Wmg Fuel Tanks (Fuel tanks 1 and 2)
20 087 pounds or 9 111 kg
Central Fuselage Tank
5 696 pounds or 2 688 kg
Total Fuel Weight
25 783 pounds or 11 799 kg 225 pounds or 99 kg
Taxiing Fuel Take-off Fuel
25 558 pounds or 11 700 kg
19 800 pounds or 9 000 kg Trip Fuel The average passenger weight is 75 kg (165 pounds), including the hand baggage weight The DOW is 32 930 kg, and the Balance Arm (arm) is 652.9 inches (20.3%MAC).
Load Sheet & Load Message The load sheet is used to indicate and compute the weight loads. The weight calculation is usual to start with the dry operating weight (DOW). If there is no adjustment to crew or panty, the basic weight equal to the DOW, so enter the same value, in the example is 32 930 kg. in the basic weight box in the top left hand comer of the load sheet, and the dry operating weight box immediately under it, as shown in Figure 5-7. Then enter the take-off fuel of 11 700 kg in corresponding box and get the operating weight of 44 630 kg. These columns, for determining the allowable take-off weight (TOW) and allowed traffic load, are on the top right side of the form. There are three columns titled zero fuel, take-off and landing. which are used to calculate the maximum weight at take-off limited by maximum zero fuel weight (MZFW), other take-off limits [such as field length, climb requirement etc, except for the MZFW and maximum landing weight (MLDW)] and 11LDW respectively. Usually, these maximum weights have been given before the weight and balance calculation.
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We can get the MZFW limited TOW of 60 007 kg by addition of the MZFW of 48 307 kg and the :ake-off fuel of 11 700 kg in the left column, and the MLDW limited TOW of 60 709 kg by subtracting trip fuel of 9 000 kg from MLDW of 51 704 kg in the right column. The lowest among the three limited TOWs is the allowed weight for take-off, that is 60 007 kg in the left column. Next, enter the operating weight of 44 630 kg which has been obtained previously, in corresponding box, and then the allowed traffic load can be obtained by allowed weight for take-off minus operating weight, that is 15 377 kg. Enter the number of passengers in appropriate boxes in ''NO. OF PASS" column in the middle left hand side of the form. The term "M", "A", "Ch" and "Inf' denote males, female adults, children and infants respectively. In this example, all the passengers are assumed to be males and the total is 138. Then enter the cargo, baggage and mail weight in corresponding box according to the load distribution given in the example as the sample load sheet shows. The column in the bottom left hand comer of the load sheet is provided to enter and determine the various weights. The total traffic load is obtained by the addition of total weight of 3 990 kg in holds and total passenger weight of 10 328 kg. In this example the weight of 14 318 kg is entered. Next, enter DOW, take-off fuel and trip fuel figures and then calculate the actual zero fuel weight, take-off weight and landing weight for current flight, they are 47 248 kg, 58 948 kg, 49 948 kg respectively. Care must be taken to ensure each of these weights is not greater than the corresponding maximum weight limit. ln the "traffic load check" column at the bottom center of the sheet, enter the allowed traffic load and the total traffic load in appropriate boxes. The "underload before LMC" is then obtained by subtracting the total traffic load from the allowed traffic load, i.e., IS 377 minus 14 318 equals to 1 059 kg. Finally, the boxes in the column at the bottom right hand comer will be entered later after the CG positions are calculated on the balance and trim sheet Balance and Trim Chart
The balance and trim chart indicates the influence of load distribution on the airplane's CG. It serves the purpose of ensuring safe balance condition and determining the CG position at ZFW and TOW as well as the trim setting for take-off. The first step is to calculate the dry operation index (DOl) by the formula presented at the bottom left comer of the load sheet, that is, INDEX= (ann- 648.5) x DOW I 29 483 DOl = (arm - 648.5) x DOW I 29 483 + 40 where: DOW - Dry Operating Weight (given in kg); Arm - the distance from 0 station to CG position at DOW (in inch); 648.5 - Reference Station for calculating the index, i.e., the distance from 0 station to CG datum (in inch). Using the number of the example: DOl= (652.9- 648.5) X 32 930 I 29 483 + 40 = 44.9 143
Enter the 00144.9 in the dry operating weight box at the top left corner of the chart. If there is no adjustment to DOl, enter the same data in ADJ. dry operating index box on the left. Once the DOl has been computed, the next step is to find the zero fuel CG position. The influence of payload distribution on the index movement will be given by the different scales for different compartment. BALANCE AND TRIM CHART NO.
BOEING 737-308
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. ..s shown in Figure 5-8, enter the loads of holds and passenger numbers in corresponding ::5
:.n compartment load column at the top left hand side of the chan. Then, enter the dry
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index scale line with the value of 44.9 and draw a vertical line until it intersects the first .!:l:;~ diagonal scale line. From here, this vertical line, representing the CG position, is moved in the :::-.::ion of the arrow at the left hand ends of the horizontal scale line, the appropriate number of :sions in accordance with the scale of each zone. Note that the scale is different for each zone; :::-~ ~ale to be used in each zone is defined at the left end of each zone. In the first zone (FWD -.:.d), the scale of this zone is defined as 1 division per 200 kg, i.e., each division represents 200 kg. .: :he given example, from the point of intersection, proceed horizontally to the left as indicated by :::~arrow, 10 divisions for 1 995 kg. You will see that each zone has an arrow pointing either to the ;::1, for a load which will move the CG forward, or to the right, for an aft movement of the CG .-\iter the vertical line has been moved the appropriate number of scale divisions horizontally, it is :::en extended vertically down to intercept the next zone (AFT Hold) diagonal scale line. This ~tersection becomes the starting point for movement on next zone. This process is repeated for each zone until the last zone (AFT PASS COMPT) scale movement is finished. If in the process, a zone has no scale arrow and scale lines for it, then the vertical is extended downward until the next zone is reached. From the end point of the horizontal line in the last zone, draw a vertical line down until the line enters the CG envelop at the bottom of the chart as shown in Figure 5-8. The zero fuel line is now extended down until it intersects the horizontal line representing the ZFW. In the example, the ZFW is 47 248 kg, so a mark is made on the vertical line. The point where the two lines intersects represents the zero fuel CG position, which in this case, is clearly inside the envelope. It is useful to mark that point with a "Z" or "ZFW". For the purpose of determining the zero fuel CG in terms of % MAC, a line should be drawn from the zero fuel CG position, upward and parallel to the nearest MAC line radiating from the index scale at the bottom of the envelope to% MAC scale at the top of the envelope. In this example, this gives a zero fuel CG of about 21% MAC. The influence of fuel on the airplane CG will be determined by the total fuel index table at the lower left side of the chart. Enter the fuel load in each tank and the total fuel weight of 11 700 kg in the fuel load column. Using the total fuel index table for the weight of 11 700 kg, you can see the weight falls between the 11 500 kg and 12 000 kg weight values. This means the fuel index falls between -3.1 and - 3.9 units and it can be obtained by interpolation calculation. lt is -3.5 units in this example. Move horizontally fuel index units of -3.5 from the zero fuel index scale on the index scale line just above MAC-diagram on the chart. A minus index units indicates the movement to the left and a positive value denotes a rightward movement In a graphical sense, this movement represents that the fuel index is added to the zero fuel ~ex to give the take-off index. From the end point, draw a vertical line down into the CG envelope to intercept the horizontal line representing the aircraft weight at take-off (i.e. TOW). This intercept determines the aircraft CG position at take-off, and must be within the envelope. Mark it with ''T.O". From this point, draw a line upward and 145
parallel to the nearest MAC radiating line to give the take-off CG position of 19% MAC in the example. From the calculated point on the MAC scale (19% in the example), a line is drawn vertically up to the appropriate stabilizer scale for the flap setting for take-off. Note that there is a line for 15° flap and another for 1o and 5° flap. The take-off flap setting would be determined during performance calculations. In the example, the flap setting used is 5°, which gives a stabilizer of 4
314
•
Finally, zero fuel CG position and take-off CG position in terms of% MAC as well as the stabilizer setting are entered in the appropriate boxes in the lower left-hand comer of the balance and trim chart.
A320 The weight and balance calculation for an A320 aircraft is similar to that for a Boeing 737-300. The load sheet is used to record and compute the weight loads and the load and trim sheet allows the determination of aircraft CG location (% MAC) in function of dry operating weight, pantry adjustment, cargo loads, passengers and fuel on board. Hereafter is a description of the load and trim sheet utilization (see Figure 5-9). Data: Dry Operating Weight = 93 000 lb and CG = 26 % Deviation or adjustment =200 lb in zone F Cargo = 10 500 lb as : cargo 1 = 4 500 lb ; cargo 3 = 2 500 lb cargo 4 = 1 000 lb ; cargo 5 = 2 500 lb Passengers (165 lb I PAX)= 156 PAX as: cabin OA = 40; cabin OB = 66; cabin OC =50 Fuel =30 000 lb Description: A. Report master data in CD. B. Compute dry operating weight index using the formula indicated in® and repot in@. C. Report weight deviation in @ and read corresponding index in @. D. Calculate corrected index and report in ®. E. Report cargo weight and PAX number in (J). F. Enter index scale ® with corrected index and proceed through cargo and passengers scales as shown in®. Then, from the final point (cabin OC), draw a vertical line down to the zero fuel line @.
G. Check intersection with zero fuel line determined in table ® is within the Max zero fuel weight and zero fuel operational limits, if not rearrange cargo loading. H. Read in table @ fuel index correction and carry forward in scale @. From this point draw a vertical line down to take-off weight line @.
I. Read take-off CG on CG scale 146
®.
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Figure 5-9 A320 - Load and Trim Sheet 1117
SECTION D
CHANGING LOADING CONDITION
Anytime weight is either added to or subtracted from a loaded airplane, both the gross weight and the center of gravity location will change. The solution of such a problem is really a simplified loading problem. Instead of calculating a weight and moment for every section of the aircraft, it is only necessary to compute the original weight and moment and then the effect the change in weight had. Often in these problems the original CG is expressed in percent of MAC and it is necessary to convert this to an arm for the entire aircraft. Hereafter is an example for DC-9, what is the new CG if the weight is removed from the forward compartment under Loading Condition WS-1 (see Figure 5-10). LOADING CONDITIONS
WS-1
W S-2
WS-3
WS-4
WS·5
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90,000
85,000
84,500
81,700
88,300
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28.4%
19.8~;,
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25.5%
2.500
1.600
3,000
2,100
3.300
WEIGHT CHANGE (POUNDS)
FWD COMPT CENTROID - STA 352.1 AND - 227.9 INDEX ARM AFT COMPT CENTROID - STA 724.9 A."'D ·•144.9 INDEX ARM MAC- 141.5 INCHES, LEMAC - STA 549.13, AND -.30.87 INDEX AA\4
Figure 5-10 DC-9-Weight Shift
It is sometimes necessary to convert a CG position expressed in percent of MAC to the CG in
inches aft of Datum. This is just the reverse of the process described above. This is done in two steps. A. Convert the CG in percent of MAC to CG in inches aft ofLEMAC. This is done by using the fonnula: CG (inches aft ofLEMAC) =(CG% ofMAC I 100%) x MAC Load condition WS-1 gives a CG of 22.5 % and a length of MAC of 141.5 inches. The formula is: CG (inches aft of LEMAC) = (22.5% I 100%) x 141.5 = 3 I .84 inches B. Add the CG in inches aft of LEMAC to the distance from datum to LEMAC. In Figure 5-10, LEMAC is 549.13 inches aft of datum. CG (inches aft ofDatum)= 549.13 + 31 .84 = 580.97 inches Use the original weight and CG to calculate the original moment/1 000. Next, use the weight change and station to determine the moment/! 000 change. Weight Moment/1 000 90 000 Original Weight 52 287.08 -2500 - 880.25 Weight Change New Weight 148
87 500
51 406.83
~ote:
A reduction in weight results in a reduction in moment/! 000, while an increase in ~ight results in an increase in moment/1 000. Determine the new CG: CG = (51406.83 I 87 500) x 1 000 = 587.51 inches Convert CG to percent of MAC: CG (inches aft ofLEMAC)= 587.51-549.13 = 38.38 inches CG (% ofMAC)=(38.38 + 141.5) x 100%=27.1% When a portion of an aircraft's load is shifted from one location to another, the CG of the .oaded aircraft will change as well. Also, the CG will follow the weight That is, if weight is shifted :earward, the CG will move rearward as well; and if weight is shifted forward, the CG will move forward. To calculate the effect of a weight shift on CG position, three numbers must be known: the weight shp:ted, the distance the weight was moved, and the total weight of the aircraft. The formula used is: Change in CG = Weight Shifted x Distance Shifted I Total Weight Another question asks what the effect on CG is if weight is shifted from the forward to aft cargo compartment under load condition WS-1 (see Figure 5-10). Load condition WS-1 gives the total weight as 90 000 pounds and the weight shifted as 2 500 pounds. The distance shifted is the difference between the forward compartment centroid (352.1 inches) and the aft compartment centroid (724.9 inches), which is 372.8 inches (724.9- 352.1).
Note: These centroids are distances aft of the datum line. The index arms are distances from the CG index and will be discussed in a later example. Notice however, that the difference between the two index arms is also 372.8 inches [144.9- (-227.9) = 372.8]. The solution is: Change in CG = 2 500 lbs x 372.8 inches I 90 000 lbs = 10.4 inches If weight is shifted forward, the CG will move forward as well. This is expressed by writing the distance shifted as a negative number. If weight is shifted from the aft to the forward cargo compartment, the distance shifted is _-372.8 inches. For example, a question asks about such a shift of 1 800 pounds with an aircraft total weight of 85 000 pounds. The formula is: Change in CG = 1 800 lbs x (-372.8 inches) I 85 000 lbs = -1.89 inches If require an answer in percent of MAC. The change in CG can be converted to a percent of
MAC by using the formula: Change in CG (% ofMAC) = (Change in CG I MAC)
x
100%
The CG sometimes can be expressed an index arm. Index arm is the distance, in inches, from an index set at a point close to the normal CG location. A positive index arm is a point aft of the index and a negative index arm is a point forward of the index. For example, Figure 5-10 shows LEMAC as having an index arm of -30.87 inches or 30.87 inches forward of the index. The index point for all questions on this test is 580.0 inches. The CG in index arm is calculated by the formula: CG (Index Arm) = CG (inches aft of Datum) -580 inches 149
Using the data from load condition WS-5, the formula is: CG (Index Arm)= 585.21 - 580 = +5.21 inches
SECTION E FLOOR LOADING LIMITS In addition to ensuring that an aircraft is loaded within its weight and balance limits, it is important to make sure that the floor of a cargo compartment is not overloaded. The load limit of a floor is stated in pounds per square foot The questions on the test require you to determine the maximum load that can be placed on a pallet of certain dimensions. For example: what is the maximum weight that may be carried on a pallet which has the dimensions of 37 inches x 39 inches, when the floor load limit is 115 pounds per square foot, the pallet weight is 37 pounds, and the weight of the tiedown devices is 21 pounds? The first step is to determine the area of the floor (in square foot) covered by the pallet. This is done by multiplying the given dimensions (which calculates the area in square inches) and dividing by 144 (which converts the area to square foot). 37 inches x 39 inches I 144 square inches = 10.02 square feet The next step is to determine the total weight that the floor under the pallet can support, by multiplying the area times the floor load limit given in the question. 10.02 square feet x 115 pounds per square foot= 1 152.39 pounds
The final step is to determine the maximum weight, which can be placed on the pallet by subtracting the weight of the pallet and the tiedown devices from the total load limit. 1 152.39 pounds -58 pounds= 1 094.39 pounds The weight on the pallet must be equal to or less than this number (1 094.39, in this example). If it is more than this number, the combination of cargo, pallet, and tiedown weight would exceed the floor load limit A review of the test questions reveals that the closest answer choice is always equal to or slightly less than the floor limit. All the calculations in this section were performed with a calculator carrying all digits to the right of the decimal point forward for the next step of the problem. The explanations show only two places to the right of the decimal. A variation of the pallet loading problem is to determine the minimum floor load limit (in pounds per square foot) required to carry a particular loaded pallet For example: what is the minimum floor load limit to carry a pallet of cargo with a pallet dimension of 78.9 inches x 98.7 inches, and a combination weight of pallet, cargo, and tiedown devices of9 896.5 pounds? The first step is to determine the floor area, multiplying the dimensions and dividing by 144 (78.9 x 98.7 I 144 = 54.08 square feet). The second step is to determine the minimum required floor limit by dividing the total weight of the pallet, cargo, and tiedowns by the pallet area (9 896.5 I 54.08 = 183.00 pounds per square foot). The correct answer must be at or above this weight (183.00 pounds, in this example).
ISO
CHAPTER 6 FLIGHT OPERATIONS SECTION A AIRSPACES The national airspace is divided into controlled airspaces and uncontrolled airspace. The controlled airspaces include Class A, Class B, Class C and Class D airspace, while the uncontrolled airspace is called Class G airspace (Figure 6-1). Class A
Class C
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Figure 6-1 Airspaces
The Class A airspace is high-altitude airspace, the bottom of Class A airspace is at flight level (FL) 6 300 meters. There are altogether 28 high-altitude controlled airspaces by now. No person may operate an aircraft within Class A airspace unless a proper authorization from ATC has been received prior to entry. During flight within Class A airspace, you must comply with the Instrument Flight Regulation (IFR) and obtain separation between aircrafts from ATC. In addition, you must keep essential vertical separation from obstacles. The Class B airspace is middle-low altitude controlled airspace, which extends from FL 600 meters to FL 6 000 meters, and divided into 37 middle-low altitude controlled airspaces by now. Having received a clearance from ATC, you may enter the Class B airspace and keep IFR separation between aircrafts given by the ATC. When the air condition meets Visual Flight Regulation (VFR), the pilot could file visual flight and keep VFR separation between aircrafts after being authorized by ATC. The Class C airspace is approach controlled airspace, which extends from FL 600 meters up to FL 6 000 meters and extends from tower controlled airspace to radius 50 kilometers or air corridor 151
laterally. No person could enter class C airspace unless he has received a clearance from the approach controller. During flight within the approach airspace, you should comply with IFR and keep not only the longitudinal separation between aircrafts given by the controller, but also the vertical separation between the aircraft and the obstacles. When the meteorological condition meets VFR. you may apply visual flight and keep visual separation if you have received the clearance ghen by the approach controller. The tower controlled airspace is defmed as Class D airspace, which extends from the airport ground level to the first holding level, and includes the traffic pattern. No person may operate an aircraft within the tower airspace unless a proper authorization from the tower controller has been received prior to entry. The pilot should keep IFR separation between aircrafts during flight within the tower airspace, and keep vertical separation between the aircraft and the obstacles. The pilot could apply for VFR flight if the meteorological condition meets the minimum condition of VFR. Except for the tower controlled airspace, the airspace between the surface and FL 600 meters is uncontrolled airspace (Class G airspace). Prior to entering the uncontrolled airspace, pilots need only to file flight plan. During flight within the uncontrolled airspace, pilots should keep separation from other aircrafts by himself under IFR or VFR condition. The ATC has no responsibility for the aircraft's safety. The airspace management department authorized by the State Council and the Central Military Commission sets special airspaces for political or military needs, as well as science tests. The special airspaces include danger airspace, restricted airspace and prohibited airspace. The danger airspace is divided from the territorial sky or the airspace above open sea abutting to China. The airspace management department must announce the time of effectiveness of the danger airspace by means of disseminating NOTAMs (Notices To Airmen). Civil Pilot can't fly into the danger airspace unless a proper authorization from ATC has been received. For some reasons of military or science tests, the airspace management department sets restricted airspace above China's territory authorized by the State Council and the Central Military Commission. No one may operate a civil aircraft within the restricted airspace during its effective period. The prohibited airspace is set for some particular uses or the people's benefits. No person may operate a civil aircraft into the prohibited airspace unless he has been authorized by relative airspace management department
SECTION B
NOTAMs (Notices To Airmen)
NOTAMs are time-critical information notices, which are either temporary in nature or not known about far enough in advance to permit publication in charts and other such data. NOTAM information includes such things as airport or runway closure due to maintenance, changes of 152
'":.!vigation aids and communication frequencies, radar service availability, as well as snow situation ::1 the airport and other information essential to a planned route, landing operation procedure. '-:OTAMs are so important that pilot must read them carefully during preflight preparation. There ;:e three types ofNOTAMs altogether: Class 1, Class 2 and SNOWTAM. Class 1 NOTAMs is more urgent than Class 2 NOTAMs generally. Class 1 NOTAMs must be :!isseminated 7 days ago before it becomes effective. Class 1 NOTAMs includes A, C, and D three series at present. Series A NOTAMs is put up by ATMB (Air Traffic Management Bureau) NOTAMs Office to some foreign international NOTAMs Office, which has set up Class 1 flight information exchange relationship with China. In addition, it must be broadcast to international airports Flight Information Office (FlO) and regional flight information center NOTAMs Office of China. Series C NOTAMs is released by ATMB NOTAMs Office or regional flight information center ~OTAMs Office to domestic airport FlO and China Civil Aviation Flight College (CCAFC). Series D NOTAMs is issued by airport (CCAFC included) FlO to its own belonged regional flight information center NOTAMs Office. Series A NOTAMs uses Universal Time of Coordinate (UTC) because it is issued to foreign NOTAMs Office, but Series C and D NOTAMs take Beijing Time because they are issued to or from domestic airports FlO, CCAFC, and regional flight information center NOTAMs Office. No matter what series of the NOTAMs, their identification is NOTAM, and NOTAMN is a new NOTAM, NOTAMC is a NOTAM that will cancel an issued NOTAM, NOTAMR is a new NOTAM that will replace a previous NOTAM. The following NOTAMs are two typical examples of Series A NOTAMs:
Examplel ZCZC PYO 199 081039 GGZBBBYUYX 081037 LBSFYNYX (A 0351/97 NOTAMN Q) LBSR/QIOASII/B/A/000/999
A)LBSF B)9708081035 C)9708291035 EST E)MKR FOR RWY27 OUT OF SERVICE)
Examplel ZCZC PY0388 081953 GGZBBBYUYX 081950 LTAAYNYX (A 1702/97 NOTAMC Al700/97 Q)LTBB/QLEA//N/A/000/999 153
A)LTBE B)9708081630 C)9708082100 E)RWY 09/27 EDGE LIGHTS OUT OF SERVICE Class 2 NOTAMs is issued at regular intervals to relative department by international NOTAMs Office of CAAC flight information center. Class 2 NOTAMs includes series A and series C. Series A should be disseminated 25 days before hand to oversea's relative departments, but series C should be disseminated to domestic regional flight information center NOTAMs Office 15 days in advance. SNOWTAM is a special type of NOTAMs that takes fixed fonn to reflect the snow and ice condition on the airport surface. SNOWTAM should be put out by certain airport FlO to ATMB NOTAMs Office, domestic regional flight information center NOTAMs Office and other relative airports FlO. If SNOWTAM need to be issued to foreign airports, it should be transmitted by ATMB NOTAMs"C5ffice. SNOWTAM should be disseminated hourly according to the variation of the snow or ice on the surface, and the first SNOWTAM must be sent out one hour and a half prior to the desired first take-off or landing time. The longest effective time of a SNOWTAM is 24 hours. Following is an example ofSNOWTAM: ZCZCYOPOlO GGCCCCCCCC 151605 ZBBYNYX (SWZB0004 ZBAA 11151408 SNOWTAM 0004 A)ZBAA B)1151408 C) 18L F) 5/5/5 H) 5/5/5
SECTION C ITEMS ON THE FLIGHT PLAN In order to ensure the aircraft's flight safety, pilots must carry on preflight beforehand preparations and preflight direct preparations. If pilot and dispatcher signed the dispatch release together, the aircraft may take-off with a flied ATC clearance. Pilot makes preflight beforehand preparations in the FlO one day prior to the departure time. Pilot must read NOTAMs carefully and send the flight application form to Air Traffic Services Reporting Office prior to 15:00 Beijing Time. The flight application should be authorized at least 5 hours prior to the desired departure time with an approved telegram, and if you don't receive the telegram. you could think it has been approved. Pilots should keep in mind that you couldn't think the flight application has been approved without an authorized telegram when you file a temporary flight task. 154
An IFR Flight Plan (FPL) should be filed to the Air Traffic Services Reporting Office one hour and a half prior to the desired departure time during preflight direct preparations. Items on the FPL are as follows (Figure 6-2).
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155
If the actual weather condition meets the minimum meteorological criteria, pilot-in-command and dispatcher must sign together in the dispatch release before contacting with the ground controller. Following is a typical dispatch release (Figure 6-3).
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SECTION 0
SELECTING AN ALTERNATE AIRPORT
As we learned in section C, an alternate airport must be listed in the flight plan and the dispatch release. In fact, pilot should select a departure alternate and (or) an arrival alternate. If the weather conditions at the departure airport are below landing minimums and at or above take-off minimums in the certificate holder's operations specifications, a departure alternate must be listed in the dispatch release. Weather at alternate airports must meet the alternate weather minimums in the operations specifications. In addition, the maximum distance to the departure 156
:...:~:nate for
a two-engine airplane can't be more than 1 hour from the departure airport in still wind
;:h one engine cruising. The distance to the alternate airport for an airplane with three or more
=::gines can't be more than 2 hours from the departure airport in still air with one engine :.:1operative. Alternate airport for destination- Domestic Operation Air Carriers: Unless the forecast ·.\'eather conditions at the destination meets following criteria, an alternate airport must be listed in :.1e dispatch release for each destination airport; If the weather at the first listed alternate is marginal, !t
least one additional alternate must be listed. For the period from 1 hour before to 1 hour after the
estimated time of arrival: A. The ceiling must forecast to be at least 450 meters above the MDH (or DR) or 600 meters AGL, whichever is higher; and B. The visibility must forecast to be 4 800 meters or 3 200 meters greater than the applicable instrument approach visibility minimums, whichever is greater. Weather at alternate airports must meet the alternate weather minimums in the operations specifications. Alternate airport for destination- International Operation Air Carriers: An alternate airport must be listed in the dispatch release for all IFR flights longer than 6 hours. An alternate airport is not required for an international flight if it is scheduled less than 6 hours and the weather forecast for the destination meets certain criteria. For the period from 1 hour before to 1 hour after the estimated time of arrival:
A. The ceiling must forecast to be at least 450 meters above the visual circling approach MDA or the mstrument approach MDA (or DA) or 600 meters AGL, whichever is higher; and B. The visibility must forecast to be 4 800 meters or 3 200 meters greater than the applicable instrument approach visibility minimums, whichever is greater. Besides these conditions, an alternate airport is not required for a certain route that has been authorized without an alternate airport, if the airplane bas sufficient fuel. Weather at alternate airports must also meet the alternate weather minimums in the operations specifications. The alternate weather minimums include MDH (or DH) and visibility, which could be calculated by reference to the authorized operations minimums of the airport selected as alternate
airport A. For an airport with only one set of approach facility, MDH (or DH) must be added at least 120 meters, and visibility must be added at least 1 600 meters; B. For an airport with two or more sets of precision approach facilities and with different runways, DH must be added at least 60 meters, be added visibility must add at least 800 meters, whichever is higher from two lower runways. Pilots must keep in mind that alternate weather minimums are for planning purposes only and do not apply to actual operations. If an air carrier flight actually diverts to an alternate airport, the crew must use the actual landing weather minimums shown on the instrument approach procedure 157
chart for that airport.
SECTION E ATC CLEARANCES As an airline pilot, you can't operate an airplane in Class A, B, C or D airspace under IFR condition unless you have filed an IFR flight plan and received an appropriate clearance from the tower controller. Usually, IFR clearances contain following items: A. Aircraft identification (usually flight number); B. A clearance limit (usually destination); C. Authorized SID or transition route; D. Route of flight; E. Flight Level;
F. Other special information, such as SSR transponder code, fHght instructions after take-off: etc. The following examples are two typical ATC clearances: A. "China Southern 3403, cleared to Chengdu via BH three departure, flight planned route, FL 9 000 meters, aquawkA2101." B. "China Southwest 4102, cleared to Chengdu via flight planned route, Flight Level9 600 meters, aquawk A0631, after departure maintain runway heading, climb and maintain 900 meters QFE. When airborne, contact (Beijing) approach 129.0." The words "ilight planned route'' replace the route listed in the FPL. The tower controUer will still state the destination airport, the FL, the SID and the SSR transponder number. When you received an ATC clearance, you can't deviate from it (except in an emergency) unless an amended clearance is received. If you are uncertain of the meaning of an ATC clearance or the clearance appears to be contrary to a regulation, you should request a clarification immediately. When you received a clearance, you should always read back controller's instructions quickly. For a typical transportation airport, pilots usually apply for following several clearances from the ground controller before take-off. The first clearance is push back. In order to save stop time of the landing airplane, pilots usually stop the airplane face to the waiting room. Pilots should request push back prior to the estimated time of departure. If the ground controUer anticipates longer delay for IFR flight, he will establish gate hold procedure. The idea is to hold airplane at the gate rather than cause congestion and unnecessary fuel bum on the taxiways while waiting for an IFR release. Ground controller will instruct airplane when to start engines. The second clearance is start up. Pilots must request start up after the aircrafts have been pushed back. Occasionally, an aircraft will be held pretaxi due to taxiways traffic heavy. If this happens to an aircraft waiting for taxi, the ground controller should notify the pilot-in-command of the time of take-off.
158
The third clearance is pretaxi. After start up, the pilot-in-command should call ground ;::1rroller for taxi. Pilots must taxi aircrafts along the given taxiways to a clearance limit, which ..,:,-uall.y is the holding point outside the take-off runway. Following is a conversation of pilot-in-command (P) and ground controller (C). P: Wuhan ground, CXN4308, 10 minutes before start up, destination Chengdu, request ATC clearance. C: CXN4308 is cleared to Cbengdu via flight planned route, flight level 9 600 meters, aquawk A3435. After departure, maintain runway heading, climb and maintain 900 meters on QFE. Contact Wuhan approach 119.1. P: (read back). C: That's correct. P: Wuhan ground, CXN4308, request departure information. C: CXN4308, departure runway 09, wind 80 degrees, 6 meters per second, visibility 3 kilometers, temperature 23, dew point 20, QFE 1023. P: Runway 09, QFE1023, CXN4308. P: Wuhan ground, CXN4308, stand 7, request push back and start up. C: CXN4308, push back and start up approved, temperature 23. P: Ground, CXN4308, request taxi. C: CXN4308, taxi via taxiway C and X to holding point runway 09. P: Taxiway C and X, runway 09, CXN4308. P: Ground, CXN4308, approaching holding point runway 09. C: CXN4308, contact tower 130.0. P: Tower 130.0, CXN4308.
SECTION F TAKE-OFF PROCEDURES On 26 Feb, 2001, CAAC formally issued and enacted "The rules and regulations for aircraft aerodrome operating minima" (Regulation No, 98) (CCAR-97FS-Rl), which provided the principles of take-off minimums.
FACTORS CONCERNING TAKE-OFF MINIMUMS A. Avoidance of adverse terrain and obstacles. B. Aircraft operating capability and performance. C. VISual navaids available. D. Runway condition. E. Navaids available. F. Malfunctions (such as engine failure). 159
F. Adverse weather including runway contamination, side wind etc.
DESCRIPTION OF TAKE-OFF MINIMUMS Normally, take-off minimums are described only by using visibility. However, if the obstacles must be seen and avoided during departure, take-off minimums should include visibility and ceiling and the exact position of the obstacles should be marked out on the procedure published. Moreover, if an SID specifies minimums climb gradient required by obstacle clearance and the aircraft can meet the gradient, take-off minimums can be described only by visibility.
TAKE-OFF MINIMUMS • The ceiling of the take-off minimums should be at least 60 meters higher than the controlled obstacles and be rounded to 10 meters. • For single engine aircraft, ceiling not below 100 m, visibility not less than 1 600 m. • Multi-engine transport take-off minimums:
Basic Standard Visibility for two engine aircraft is 1 600 m; visibility for three/four engine aircraft is 800 m. With this standard, the alternates of the selected airport should meet the following requirement: A. The weather and equipments of alternate is supportive of landing aircraft with engine failure, the aircraft can at least climb to the MSA of the route and maintain that altitude to the alternate of the departure airport. B. One/two engine aircraft, the distance to the departure airport is normally no greater than the distance covered by the aircraft in one hour with one engine failure at cruise speed in calm wind. C. 1bree/four engine aircraft, the distance to the departure airport is normally no greater than the distance covered by the aircraft in one hour with one engine failure at cruise speed in calm wind. The above mentioned requirements also applies to the airports with take-off minimums less than the landing minimum of the runway available with engine failure.
Expanded Standard For turbine aircraft with two or more engines, if the flight performance and cockpit equipments are typically fit for low visibility operation and the flight crew qualified (see CAAC Regulation N0.5), in accordance with the runway visual equipments, the standards specified in Figure 6-4, which are less than the basic take-off minimums, can be employed. • The visibility required to avoid the obstacles or see them clear is the shortest from DER to the obstacle plus 500 m or 5 000 m, which ever is smaller. But for CAT AlB aircraft, the minimums visibility should be no less than 1 500 m, for CAT CID aircraft, the minimums visibility should be no less than 2 000 m. 160
Visual NAVAJD available
RVRNlS A.B,C
D,E
high intensity r/w side lights and middle lights with 3 RVR observing point
150
200
r/w side lights and middle Lights (no RVR observing point)
200
250
r/w side lights and middle line markers (no RVR observing point)
250
300
r/w middle line markers, no light (only daytime)
500
500
Figure 6-4 Expa.nded Standard
SECTION G
INSTRUMENT APPROACHES
This section is limited to rules and procedures common to most, or all approaches, or procedures that may be used in connection with published instrument approaches. Contact and visual approach are both lFR authorizations to proceed to an airport visually. A visual approach may be authorized by ATC to reduce pilot or controller workload and to expedite traffic by shortening flight paths to the airport. When requested by the aircraft and if so prescribed by the appropriate ATS authority an arriving aircraft may be cleared to descend subject to maintaining own separation and remaining in visual meteorological conditions if reports indicate that this is possible. For successive visual approaches, radar or non-radar separation shall be maintained until the pilot of a succeeding aircraft reports having the preceding aircraft in sight The aircraft shall be instructed to follow and maintain separation from the preceding aircraft. Transfer of communications should be effected at such a point or time that clearance to land or alternative instructions can be issued to the aircraft in a timely manner. The weather must be VFR and the pilot must report either the airport or the preceding aircraft in sight. Either the pilot or ATC may initiate a visual approach. A contact approach may be initiated only by the pilot. If a pilot-in-command reports or if it is clearly apparent to the ATC unit that he or she is not familiar with an instrument approach procedure, the initial approach level, the point (in minutes from the appropriate reporting point) at which procedure turn will be started, the level at which the procedure turn shall be carried out and the final approach track shall be specified, except that only the last-mentioned need be specified if the aircraft is to be cleared for a straight line approach. The missed approach procedure shall be specified when deemed necessary. If visual reference to terrain is established before completion of the approach procedure, the entire procedure must nevertheless be executed unless the aircraft requests and is cleared for a visual approach. A particular approach procedure may be specified to expedite traffic. The omission of a specified approach procedure will indicate that any authorized approach may be used at the discretion of the pilot. Succeeding aircraft shall be cleared for approach when the preceding aircraft: A. has reported that it is able to complete its approach without encountering instrument meteorological conditions; or 161
B. is in communication with and sighted by the aerodrome control tower and reasonable assurance exists that a normal landing can be accomplished. Separation shall be provided between an aircraft cleared to execute a visual approach arid other arriving and departing aircraft. The weather need not be VFR but the aircraft must be clear of the clouds, have at least 1 mile visibility and be able to proceed to the landing airport visually. An IFR flight may be cleared to execute a visual approach provided that the pilot can maintain visual reference to the terrain and: A. the reported ceiling is at or above the approved initial approach level for the aircraft so cleared; or B. the pilot reports at the initial approach level or at any time during the instrument approach procedure that the meteorological conditions are such that with reasonable assurance a visual approach and landing can be completed. When an airport bas ILS or MLS approaches to parallel runways at least 4 300 feet apart, ATC may conduct approaches to both runways simultaneously. The pilots will be informed if simultaneous approaches are in progress. To ensure safe separation between aircraft, radar monitoring is provided on the tower frequency. A pilot must report any malfunctioning aircraft receivers if he/she has been informed that simultaneous approaches are in progress. Parallel runways may be used for simultaneous instrument operations for: A. independent parallel approaches; or B. dependent parallel approaches; or C. segregated parallel operations. Independent parallel approaches may be conducted to parallel runways provided that: A. the runway centre lines are spaced by the distance specified in Annex 14, Volume I; and B. instrument landing system (ILS) and/or microwave landing system (MLS) approaches are being conducted on both runways; C. the aircraft are making straight-in approaches; D. the missed approach track for one approach diverges by at least 30 degrees from the missed approach track of the adjacent approach; E. an obstacle survey and evaluation is completed, as appropriate, for the areas adjacent to the fmal approach segments; F. aircraft are advised of the runway identification and ILS localizer or :MLS frequency; G. radar vectoring is used to intercept the ILS localizer course or the MLS fmal approach track; H. a no-transgression zone (NTZ) at least 610 m wide is established equidistant between extended runway centre lines and is depicted on the radar display; I. separate radar controllers monitor the approaches to each runway and ensure that when the 300m (1 000 ft) vertical separation is reduced; J. if no dedicated radio channels are available for the radar controllers to control the aircraft
until landing. 162
As early as practicable after an aircraft has established communication with approach control, --= :llrcraft shall be advised that independent parallel approaches are in force. This information may :.e ?rovided through the automatic terminal information service (ATIS) broadcasts. In addition, the ~:.~raft shall be advised of the runway identification and the ll.-S localizer or MLS frequency to be -~d.
Independent parallel approaches to parallel runways spaced by less than 1 525 m but not less ::.an 1 035 m between their centre lines shall be suspended under certain weather conditions, as :~escribed by the appropriate ATS authority, including wind shear, turbulence, downdrafts, ::-osswind and severe weather such as thunderstorms, which might otherwise increase as localizer :ourse and/or MLS final approach track deviations. to the extent that an unacceptable level of .:eviation alerts would be generated. Dependent parallel approaches may be conducted to parallel runways provided: A. the runway centre lines are spaced by the distance specified in Annex 14, Volume I; B. the aircraft are making straight-in approaches; C. suitable surveillance radar with a minimum azimuth accuracy of 0.3 degrees (one sigma) and update period of 5 seconds or less is available; D. as and/or MLS approaches are being conducted on both runways; E. aircraft are advised that approaches are in use to both runways (this information may be provided through the ATIS); F. the missed approach track for one approach diverges by at least 30 degrees from the missed approach track of the adjacent approach; and G. approach control has an override capability to aerodrome control. A minimum of 300 m (1 000 ft) vertical or a minimum of 6 km radar separation shall be provided between aircraft during turn-on to parallel ll-S localizer courses and/or MLS final approach tracks. The minimum radar separation to be provided between aircraft established on the as localizer course and/or MLS final approach track shall be: A. 6 km between aircraft on the same as localizer course or MLS fmal approach track unless increased longitudinal separation is required due to wake turbulence; and B. 3.7 km between successive aircraft on adjacent as localizer courses or MLS final approach tracks. Occasionally, a pilot will be asked to fly an instrument approach to a runway and then fly a visual "sidestep" maneuver to land on a parallel runway. This sidestep maneuver should be executed as soon as possible after the runway environment is in sight. If a pilot is being radar vectored when an approach clearance is received, he/she must maintain the last assigned altitude until the aircraft is established on a segment of a published route or approach procedure unless a different altitude is assigned by ATC. If a flight is being radar vectored to the final approach course and intercepts a published portion of the course, the pilot may not descend to the published altitudes until cleared for the approach. If a flight bas not been cleared for approach while on a radar vector and it becomes apparent that the current vector will take it across 163
the final approach course, the pilot should advise ATC of the situation. Do not tum to intercept the approach course unless cleared to do so. When vectoring to intercept the ILS localizer course or MLS final approach track, the final vector shall be such as to enable the aircraft to intercept the ILS localizer course or MLS final approach track at an angle not greater than 30 degrees and to provide at least 2 km (1.0 NM) straight and level flight prior to ILS localizer course or MLS final approach track intercept The vector shall also be such as to enable the aircraft to be established on the ILS localizer course or MLS final approach track in level flight for at least 3.7 km (2.0 NM) prior to intercepting the ILS glide path or specified MLS elevation angle. A minimum of 300 m (1 000 ft) vertical or a minimum of 6 km radar separation shall be provided until aircraft is established: A. inbound on the ILS localizer course and/or MLS final approach track; and B. within the normal operating zone (NOZ). A minimum of 5.6 km (3.0 NM) radar separation shall be provided between aircrafts on the same ILS localizer course or MLS final approach track unless increased longitudinal separation is required due to wake turbulence. When assigning the final heading to intercept the ILS localizer course or MLS final approach track, the aircraft shall be advised of: A. its position relatives to a fix on the ILS localizer course or MLS final approach track; B. the altitude to be maintained until established on the ILS localizer course or MLS final approach track to the ILS glide path or specified MLS elevation angle intercept point; and C. if required, clearance for the appropriate ILS or MLS approach. When an aircraft is observed to overshoot the tum-on or to continue on a track which will penetrate the NTZ, the aircraft shall be instructed to return immediately to the correct track. When an aircraft is observed penetrating the NTZ, the aircraft on the adjacent ILS localizer course or MLS fmal approach track shall be issued with appropriate beading and altitude instructions in order to avoid the deviating aircraft. Radar monitoring shall not be terminated until: A. visual separation is applied; or B. the aircraft has landed, or in case of a missed approach, is at least 2 km (1.0 NM) beyond the departure end of the runway and adequate separation with any other traffic is established. Unless ATC issues a clearance otherwise, no pilot may make a procedure turn on an instrument approach if any of the following apply: A. The flight is radar vectored to the final approach course or fix. B. The flight makes a timed approach from a holding fix. C. The approach procedure specifies "No PT". When the approach procedure involves a procedure tum, a maximum speed which is not greater than 200 KIAS should be observed from first overheading the course reversal IAF through the procedure turn maneuver, to ensure containment with the obstruction clearance area Except for 164
II and m approaches, if RVR minimums for take-off or landing are prescribed in an =:s::ument approach procedure, but the RVR is not reported for the runway intended, the ground -::oilities may be substituted. These may be found in FAA Legend 7. A pilot may not continue an approach past the final approach flx or on to the flnal approach ~gment unless the latest weather report for the airport indicates that the visibility is equal to, or ;:-eater than, the visibility required for the approach procedure. If a pilot has begun the flnal ;;:proach segment and then receives a report of below minimum conditions, he/she may continue :.Je approach to the DH or MDA. To descend below the published DH or MDA on an instrument approach, one of the following ::::mst be distinctly visible and identifiable to the pilot. Approach light system, except that the pilot may not descend below 100 feet above the :ouchdown zone elevation using the approach lights as a reference unless the recterminating bars or red side row bars are also distinctly visible and identifiable. A. Threshold; B. Threshold markings; C. Threshold lights; D. Runway end identifier lights; E. Visual approach slope indicator; F. Touchdown zone or touchdown zone markings; a Touchdown zone lights; H. Runway or runway markings; I. Runway lights. A pilot must initiate a missed approach from an ILS upon arrival at the DH on the glide slope if none of the required visual references is distinctly visible. If visual contact is lost anytime after descending below the DH but before touchdown, the pilot must start a missed approach. If a pilot loses visual reference while circling to land from an instrument approach, he/she should follow the missed approach procedure published for the approach used. The pilot should make an initial climbing turn towed the landing runway to establish the aircraft on the missed approach course. An Airport Surveillance Radar (ASR) approach is one in which an ATC radar controller provides directional guidance and distance to the runway information to the pilot. The only airborne equipment required is an operating radio receiver. The controller will tell the pilot when the aircraft is at the missed approach point and give missed approach instructions as required. If the pilot desires to execute a missed approach prior to the missed approach point, he/she should inform the controller, who will then issue missed approach instructions. All-weather category ll and m operations are based on a total system concept. The system encompasses the need for additional and more reliable ground equipment and airborne systems capable of guiding the airplane with greater accuracy to the decision height and, when appropriate, through to a landing and subsequent roll out. The pilot a is part of the system and takes an active
<:'z:.. ~ory
165
role in the operation. To this effect the pilot bas to be furnished with the necessary information to supervise all phases of the approach and landing and, if necessary, to assume manual control of the aircraft in order to complete the landing or ~arry out a missed approach procedure, if appropriate. The provision ofthe ATS is an essential part of the system concept in category n.and ill operations. System reliability and integrity is achieved through design features such as low failure rates, redundancy and a monitoring capability which allows for operational alternatives. Monitoring of all elements of the system, including both ground and airborne equipment, is essential. The pilot must be informed of any ground equipment failures affecting the status of the system, a task that is normally the responsibility of the air traffic controller. Redundancy is also an important part in providing operational reliability and it is for this reason that standby facilities are used for both ground and airborne equipment. The redundant equipment may also operate in a monitoring mode by comparing its performance with which of the primary operating equipment and may provide an alert if differences exceed established values. Guidance material concerning instrument landing system (ILS) installations, operational design and maintenance objectives as well as definitions of course structure for facility performance categories is described in Annex lO,Volume I, Attachment C to Part I. Additional requirements for category ll and ill operations are descneed in Dot 9365, Chapter 5. The facility performance categories defined in Annex 10, Part I, Chapter 3 have operational objectives which are described below: A. Category I: Operation down to 60 m (200 ft) decision height and with a runway visual range (RVR) not less than a value of the order of 800 m (2 600 ft} with a high probability of approach success. This can be regarded as a precision approach operation achieved without the need for facilities additional to those which have been in use for several years for the classic ILS approach. B. Category II: Operation down to 30m (100ft) decision height and with an RVR not less than a value of the order of 400 m (1 200 ft) with a high probability of approach success. In this category the time available in the visual phase limits the corrections which can be made to the aircraft's flight path. Consequently, improved quality of non-visual guidance and aircraft equipment from that required for category I is necessary. Improved approach and runway lighting systems are necessary to provide adequate visual cues. Carefully considered flight deck procedures and flight crew training are called for. C. Category IliA: Operation, with no decision height limitation, to and along the surface of the runway with external visual reference during the final phase of the landing and with an RVR not less than a value of the order of 200m (700ft). In practice, category IliA operations may include a decision height below 30m (100ft) to permit pilot confirmation that a safe automatic landing can be effected. In this operation the guidance and control systems must have the capability to permit the aircraft to land safely on the runway without visual reference but thereafter, during the landing roll, the pilot will normally control the aircraft by external visual references. 166
D. Category IIIB: Operation, with no decision height limitation, to and along the surface of the nmway without reliance on external visual reference, and subsequently, taxiing with external visual reference in a visibility corresponding to an RVR not less than a value of the order of 50 m (150 ft). This operation introduces a requirement to provide non-visual guidance for roll-out Depending on the taxiway configuration, extensive improvements to taxiway lighting, marking and traffic control may be required if the attainment of the lowest limits of category IllB is intended. E. Category IIIC: Operation, with no decision height limitation, to and along the surface of the runway and taxiways without reliance on external visual reference. This ultimate objective creates the need for non-visual guidance to guide the aircraft on the taxiways and on the apron. The system will also have to be applicable to emergency services and other essential vehicles, unless alternative means can be applied to provide them with facilities for rapid and safe movement while performing their tasks. The provision of aerodrome control service is considered essential when aerodromes planned for categories IT and III operations. The information to be provided to pilots is specified in Annex 11 and in the Procedures for Air Navigation Services - Rules of the Air and Air Traffic Services (PANS&AC, Dot 4444), Part IV. Guidance on the responsibilities of ATS regarding surface movement guidance and control is given in ICAO Circular 148 -Surface Movement Guidance and Control Systems. The ATS unit must ensure that pilots are kept informed of any changes in the status of airport facilities at their destinations and at their alternate aerodromes. In some locations, the ATS unit concerned may require a discrete frequency for communicating information to aircraft at the commencement of an approach and during the final approach, landing and roll-out phases. Where provided, an automatic terminal information service (ATIS) will assist operations prior to the commencement of final approach, but may not normally be updated frequently enough to eliminate the need to pass additional information to pilots engaged in operations lower than category I. Because ILS signals can be disturbed by reflections caused by aeroplanes overflying the localizer, ATS units must ensure that when category II or III operations are being conducted, aeroplanes do not take off from the landing runway after an aeroplane on final approach has reached a certain point For instance, clearance for take-off should be given so as to ensure that the departing aeroplane has overflowed the ILS localizer antenna before the arriving aero~lane has descended to 60 m (200 ft). This is necessary to preserve the integrity of the precision guidance system during the time when the landing aircraft is critically dependent on the quality of the signal in space. For the same reason, additional longitudinal separation may be required between successive aircraft conducting category IT and moperations. When designing approach procedures for use in conjunction with category IT and ill ILS facilities, it is desirable to make provisions whereby aircraft equipped for low visibility operations will not be delayed unnecessarily by aircraft not so equipped. Such consideration may require special holding procedures, or special radar vectoring 167
procedures. However, when category IT or ill operations do not prevail, all aircraft should be afforded normal priorities by A TS units . A TS units should recognize the need for aircraft to simulate low minima approaches in good weather conditions so that both crew and equipment can gain practical exposure. Approval to conduct such an exercise should be requested by the pilot and A TS units should agree to such a request whenever traffic will pennit. While this exercise is being conducted, ATS units should, where feasible, restrict take-offs and ground manoeuvring to the same extent as if actual low minimal conditions existed. When this is not feasible, A TS should advise the pilot accordingly.
SECTION H
LANDING
Except for emergencies, the landing priority of aircraft arriving at a tower-controlled airport is on "first-come, first-served" basis. When landing at a tower control, an aircraft should exit the runway at the first suitable taxiway and remain on the tower frequency until instructed to do otherwise. The aircraft should not turn onto any other taxiway unless a clearance to do so has been received. ATC furnishes pilots' braking action reports using the terms "good", "fair", "poor'' and "nil" or a combination of these terms. If you give a braking action report to A TC, you should use the same terminology.
If an aircraft requests to take off, land, or touch-and-go on a closed or unsafe runway, the pilot will be informed that the runway is closed or unsafe by ATC as "RUNWAY 18 CLOSED or RUNWAY 18 UNSAFE". and if you persists in your request, A TC will quote you the appropriate parts of the NOTAM applying to the runway and inform you that a clearance cannot be issued. Then, if you insist and in ATC's opinion the intended operation would not adversely affect other traffic, the operation will be at your own risk. Normally, you can receive current landing information during approach. Landing information contained in the A TIS broadcast may be omitted if you state the appropriate ATIS code.
SECTION I
COMMUN ICATIONS
The "Sterile Cockpit" Rule: Regulations say only those duties required for the safe operations of the aircraft are allowed during critical phases of flight. Critical phases of flight are defined as climb and descent when below 3 000 meters, taxi, take-off and landing. Excluded from the definition of critical phase of flight are any operations at or above 3 000 meters and cruise flight below 3 000 meters. Activities, which are prohibited during critical phases of flight, include filling out logs, ordering galley supplies, making passenger announcements or pointing out sights of 168
interest Activities such as eating meals or engaging in nonessential conversations are also prohibited. The following should be reported without ATC request: A. Vacating a previously assigned altitude for a newly assigned one. B. An altitude change when operating under a VFR-On-Top clearance. C. When unable to climb or descend at a rate of at least 500 feet per minute. D. When an approach has been missed. E. A change in cruising true airspeed of 10 knots or 5%, whichever is greater. F. The time and altitude (or Flight Level) upon reaching a holding fix or clearance G. When leaving an assigned holding fix or point H. The malfunction of navigation, approach or communication equipment. I. Any information pertaining to the safety of flight J. In addition to the reports listed above, when not in radar contact a pilot must report. K. When over designated compulsory reporting points. L. When leaving the final approach fix inbound on an instrument approach. M. When it becomes apparent that an estimate of arrival time over a fix is in error by more than 3 minutes. Occasionally an ATC controller will query a pilot about the aircraft's altitude or course. For example, a controller says "verify 3 000", meaning be/she wants confirmation that the aircraft is at 3 000 meters altitude. If the aircraft is not at that altitude, the pilot should reply, "Negative, maintain 2 700 as assigned. No climb or descent should be started unless specifically assigned by the controller. Pilots should notify controllers on initial contact that they have received the ATIS broadcast by repeating the alphabetical code used appended to the broadcast. For example, "Information Sierra received".
SECTION J
SPEED ADJUSTMENTS
ATC controllers often issue speed adjustments to radar-controlled aircraft to achieve or maintain the desired separation. The following minimum speeds are usually observed: Aircraft operating above 3 000 meters: not less than 250 knots or the equivalent mach number, except the pilot is unable to do it. Anival aircraft below 3 000 meters: Turbojet aircraft. A speed not less than 210 knots; except 20 miles from threshold, a speed not less than 170 knots. Piston and turboprop aircraft. Not less than 200 knots; except 20 flying miles from threshold, a speed not less than 1SO knots. Departure aircraft: Turbojet aircraft. A speed not less than 230 knots. Piton engine and turboprop aircraft. A speed not less than 150 knots. Helicopters: A speed not less than 60 knots. 169
If an ATC controller assigns a speed, which is too fast or too slow for the operating limitations of the aircraft under the existing circumstances, the pilot should advise ATC of the speed that will be used. The controller will then issue instructions based on that speed. Speed adjustments are not achieved instantaneously. Aircraft configuration, altitudes and speed determine the time and distance required to accomplish the adjustment Because of the great differences in speed and operating characteristics of helicopters and airplanes, they are usually assigned different routing. Occasionally, larger/faster helicopters are integrated with fixed-wing aircraft. These situations could occur on IFR flights, routes that avoid noise-sensitive areas or when the helicopter is assigned runways or taxiways to avoid downwash in congested areas.
SECTION K
HOLDING
A holding pattern is a procedure designed to keep an aircraft within a specified airspace while awaiting further clearance from ATC. In most cases it is used as a method of delaying a flight on its planned route.
THE ELEMENTS OF A HOLDING PATTERN A holding pattern involves holding fix, two turns and two straight-and-level legs as shown in Figure 6-5. The holding fix can be a VOR, an NDB, airway intersections, a point defined by a specific DME distance from a VOR on a specific radial, or an arbitrary RNAV-fix for aircraft appropriately equipped. A standard holding uses right hand turns and a one minutes inbound leg. The length of the outbound leg may vary a little to compensate for hctdlng"" wind drift. Above 14 000 feet the leg length is Figure 6-5 Standard Holding Pattern extended to 1.5 minutes. It may also be extended by ATC. Some holding patterns, rather than being based on time, are based on DME distance outbound. If a nonstandard pattern is to be flown, ATC will specify left turns. At and below 14 000 feet MSL (no wind), the aircraft flies the specified course inbound to the fiX, turns to the right 180°, flies a parallel course outbound for 1 minute, again turns 180° to the right, and flies 1 minute inbound to the fix. Above 14 000 feet MSL, the inbound leg length is 1-o.s minute. During turns in a holding pattern, the rate of turn or bank angle should be 3° per second or 25e bank, whichever is less. 170
:be timing for outbound leg usually start at abeam or over the holding fix, which ever occur ~
If that position cannot be detennined (e.g. because the fix is a DME fix), start timing when
~ _ :omplete
the turn outbound.
ENTERI NG A HOLING PATTERN Entering a holding pattern sometimes requires some maneuvering, as you might be -=;:oaching the pattern from any direction. There are three types of entrance maneuvers for a -..:.-:em. The type of entry you use depends ::: :·our heading as you approach the holding :::_,_ Figure 6-6 shows the three sectors for a :-.;ht-hand
pattern.
Entry
sectors
are
Sector p
:s:ablished by forming angles of 70° on the .:0lding pattern side of the holding course ~~d
110° on the non-holding side. For
eft-band patterns all things discussed below
SectorT
2pply in an analogous way. Entering from sector III (D) you will use a Direct Entry, :rom sector II(T) a Teardrop Entry, and from
Figure 6-6 Entry Sectors
sector I (P)a Parallel Entry.
Direct Entry The direct entry procedure is the most simple one and most published holdings are designed such that inbound traffic can most often use this simple method of entry (see Figure 6-7).
In a direct entry you simply fly to the fix and start the turn to the outbound leg. If your entry requires an outbound tum of less than 180°, start the turn with an appropriate delay. For instance, if the required tum is only 145°, start your turn 45°/ 3°/s=lS seconds after crossing the holding fix.. Without that delay your outbound leg would be too close to the inbound leg and the following turn at the outbound end would carry you out of the holding area
Figure 6-7 Direct Entry Procedure
Teardrop Entry Fly to the fix and tum to a heading which starts a 30 degree teardrop on the holding side. Fly this heading for 1 minute and then start the turn to the inbound leg (see Figure 6-8).
171
Parallel Entry After passing the holding fix, tum to the outbound heading to parallel the inbound course, then tum inboood to the holding fix (see Figure 6-9).
Figure 6-8 Teardrop Entry Procedure
Figure 6-9 Parallel Entry Procedure
Example 1 A plane, :MH 60°, receive this A TC
TeardrOP
H
iJ
clearance: " ... HOLD EAST OF THE ABC VORTAC ON THE ZERO NINER ZERO
Direct
RADIAL, LEFT TURNS ... " (see Figure 6-10). What is the recommended procedure to enter the holding pattern? First determine the holding fix, then dragging it on the holding radial given by
Parallel Hold on 090" Radllll Non-Standard
Left Turns
ATC, this example inbound leg 90°, then return back to fix. Then draw the pattern from the fix with turns in the direction specified, this example is left turns.
160"
Figure 6-10 Parallel Entry 360"
Teardrop
The entry procedure is based on the
ft
Parallel
aircraft's heading. To determine which entry procedure to use, draw a line at 70° angle from the holding fix. With a heading 60°, a parallel entry would be used.
tto•
Examplel A plane, MH 60°, receive this ATC clearance: "... HOLD SOUTII OF THE ABC VORTAC ON? THE ONE EIGHT ZERO RADIAL ..." (see Figure 6-11). 172
Direct
Direct
Hold on 180" Radial Standard Right Turns
Figure 6-11 Direct Entry
What is the recommended procedure to enter the holding pattern? First determine the holding fix, then dragging it on the holding radial given by ATC, this =x1Illple inbound leg 180°, then return back to fix. Then draw the pattern from the fix with turns in ".:ie direction specified, this example is right turns. The entry procedure is based on the aircraft's heading. To determined which entry procedure to _ ". draw a line at 70° angle from the holding fix. With a heading 60°, a direct entry would be used.
SECTION L
CHARTS FOR INSTRUMENT FLIGHT
INTRODUCTION Instrument flight may be broken down into three broad phases. The departure phase takes you from the airport to the enroute structure. The enroute phase is used to travel from one location to another, and the arrival phase pennits you to transition from the enroute structure to your destination. The arrival phase may begin with a published arrival procedure and usually ends with an instrument approach. Jeppesen Sanderson, Inc., a private firm. publishes instrument charts for each of these phases. Most civil operators, including most air carriers, use Jeppesen charts. Therefore, it is important to be familiar with Jeppesen charts fonnat, and as an airline pilot, you must be able to analyze Jeppesen charts.
INSTRUMENT APPROACH CHARTS The standard instrument approach procedure, or lAP, allows you to descend safely from the enroute altitude to a relatively low altitude near a runway at your destination. In the nonnal case of a category I instrument landing system (ILS-1) approach, you typically arrive at a point located approximately one-half mile from the runway threshold at an altitude of 200 feet above the elevation of the touchdown zone. At this point, if certain visual requirements are met, you may continue to a landing using visual references. If the visual requirements can't be met at this point, or if the required visual cues are lost after passing it, you must discontinue the approach and follow the missed approach procedure. Although there are many different types of approaches in use, most have common procedures and chart symbology. Therefore, your ability to read one approach chart generally means you will be able to read others. This section is designed to help you become proficient at reading charts. An ILS/DME approach and a NDB/DME approach chart has been selected, since this chart includes most ofthe features found on other approach charts. Approach Segments
Before looking at approach chart symbology, it is helpful to have a basic understanding of an 173
approach procedure. An instrument approach may be divided into as many as five segments: arrival, initial, intermediate, fmal and missed approach segment. These segments often begin and end at designated fixes (Figure 6-12).
Approach Fix(FAF)
Initial
Intermediate Approach Fix (IF)
Approach Fix{IAF)
Figure 6-IZ Five Degments oflnstrument Approach
Arrival Routes Arrival routes, although technically not considered as approach segments, are an integral part of many instrument approach procedures. They provide a link between the enroute and approach structures. Although an approach procedure may have several arrival routes, you generally use the one closest to your enroute arrival point When a arrival route is shown, the chart provides the course or bearing to be flown, the distance, and the minimum altitude.
Initial Approach Segment The purpose of the initial approach segment is to provide a method for aligning your aircraft with the approach course. This is accomplished by using an arc procedure, a course reversal, or by following a route which intersects the fmal approach course. An initial approach segment begins at the initial approach fix, and usually ends where it joins the intermediate approach segment The initial approach fix is usually depicted on the chart with an IAF. A given procedure may have several initial approach segments. Where more than one exists, each will join a common intermediate segment, although not necessarily at the same location.
Intermediate Approach Segment The intermediate segment is designed primarily to position your aircraft for the final descent to the airport. During it, you typically reduce your airspeed to at or near the approach airspeed, complete the landing checklist, and make a final review of the approach procedure and applicable
mininiiuns.
Like the arrival route and initial approach segment, the chart depiction of the
intermediate provides you with course, distance, and minimum altitude information. The intermediate segment is normally aligned within 30° of the fmal approach course, it begins 174
.:: ·ne intermediate fix (IF) or point, and ends at the beginning of the fmal approach segment In so: ::::e cases, an IF is not shown on the approach chart In this situation, intermectiate segment begins ~ ~ point where you are proceeding inbound to the final approach fix, is properly aligned with the :":::al course, and is located within the prescribed distance from the final approach fix (FAF).
.=-:nal Approach Segment The purpose of the final approach segment is to allow you to navigate safely to a point at ···hicb, if the required visual references are available, you can continue the approach to a landing. If :· ou cannot see the required cues at the missed approach point (MAPt), you must execute the missed approach procedure. The final approach segment for a precision approach begins where the glide slope is intercepted at the minimum glide slope intercept altitude specified by the approach chart. If ATC authorizes a lower intercept altitude, the final approach segment begins upon glide slope interception at that altitude. For a nonprecision approach, the fmal approach segment begins either at a designated FAF or at the point where you are aligned with the final approach course. The final approach segment ends either at the designated missed approach point or when you land. Although the charted fmal approach segment provides you with course and distance information, many factors influence the minimum altitude to which you can descend. These include the type of aircraft being flown, the aircraft's equipment and approach speed, the operational status of navaids, the airport lighting, the type of approach being flown, and local terrain features . .'lfzssed Approach Segment The purpose of the missed approach segment is to allow you to safely navigate from the MAPt to a point where you can attempt another approach or continue to another airport Evezy instrument approach will have a missed approach segment along with appropriate heading, course and altitude information. The missed approach segment begins at the MAPt and ends at a designated point, such as an initial approach or enroute fix. The actual location of the MAPt depends upon the type of approach you are flying. For example, during a precision approach, the MAPt occurs when you reach a designated altitude called the decision height (DH). For nonprecision approaches, the missed approach point usually occurs at a fiX defined by a navaid. Chart Layout
Jeppesen instrument approach charts portray the instrument approach procedures which are available at a given airport. Generally, a sheet of Jeppesen chart consists of four sections: heading section, plan view, profile view and, landing minimums (Figure 6-13).
Heading Section On Jeppesen charts, the heading section identifies the airport, the primary approach facility, communication frequencies, and, if available, minimum safe altitude information. Jeppesen lists the city and state (item 1) on the upper right-hand comer where the airport is located, followed by the airport name on the next line (item 2). The procedure name (item 3) indicates the type of approach system used during final approach and the runway served. The 175
I
p .R. OF C:HiNA ..A
.
(PEKING)
-~-CAPITAL
LS·DME Rwy 18R DME Rwy 18R *110.3 ltG
Figure 6-13 JLSIDME and NDBIDME Approach
176
minimum equipment required to fly the approach is indicated by the procedure name and notes on the approach chart This approach chart uses an ILS DME and a NDB DME to serve runway 18R at CAPITAL. Ifyour aircraft is capable of flying an ILS DME or a NDB DME approach, you may use
this chart The minimum safe altitude (MSA) provides I 000 feet of obstruction clearance within 25 nautical miles of the indicated facility (unless some other distance is specified). The MSA may be divided into several sectors which are defined by radials or bearings to the navaid. For Beijing CAPITAL, there are altogether four sectors, the MSA is 7 100 feet from 96° to 21 0°, 5 500 feet 210° to 276°, 2 800 feet 276° to 30°, and the sector from 30° to 96° is a prohibited area (item 7). The four sectors are divided by reference to LG NDB. There are several important features of the MSA. First, it provides only obstruction clearance within the sector. Neither navigation nor communication coverage is guaranteed. Second, the MSA is designed only for use in an emergency or during VFR flight, such as during a VFR approach at night And third, MSA is not listed for every approach. Its omission may be due to the lack of ari easily identifiable facility upon which to orient the MSA circle. Jeppesen approach charts present communication frequencies in the sequence in which you normally use them. For example, your first contact is with Beijing Approach on frequency 129.0, followed by Beijing Tower 118.1, then Ground 121.7. In addition, you may receive arrival information on the frequency of ATIS 127.6 (item 11). Jeppesen charts normally present the publish date and the effective date if a chart is issued before it can be used. In this situation, you should continue to use the previous chart until the effective date (item 9). If there is no effective date, you may use the chart upon receipt
Plan View The plan view displays an overhead presentation of the entire approach procedure. Since approach charts are intended for use during instrument weather conditions, they show only limited terrain and obstruction information. However, when the procedure is flown as depicted, obstruction clearance is provided throughout the approach. Navaid facility boxes identify various navaids which appear on the approach chart. On Jeppesen charts, a rectangular box is used to depict a NDB, VOR, or LOM facility, while an oval shape is used to depict an ILS facility. No matter what shape of the box, it mainly provides frequency and Morse code identification. Jeppesen uses shading around the primary facility upon which the approach is based. In this case, the primary facilities are an ILS localizer and a NDB. The ILS localizer is aligned on a course of 179° with frequency 110.3 MHz (item 16), while the NDB 's frequency is 325kHz with the identifier LG (item16). The letter "f' is used to indicate an ILS localizer. On the plan view, various types of initial approach segment are depicted according to
associated arrival chart In this case, the announced initial approach segment is base tum with IAF at LG NDB. Category A and B aircra.fts should follow the course of019° to a distance of7.3 DME, while category C and D aircrafts should follow the course of 030° to a distance of 8.5 DME (item 177
17). The identifier of the DME is ILG. If you received a holding clearance rather than an approach clearance during arrival, you could join the holding pattern depicted on the plan view. For this example, you could join LG or OB holding pattern according to the arrival route and the ATC clearance. The minimum holding altitude of the LG holding pattern is 3 070 feet, and its outbound course is 17()0. The missed approach path and the associated holding pattern also are shown on the plan view. The details of the missed approach procedure are described on the profile view. In this case, the holding pattern is shown on LG along with its minimum holding altitude, inbound and outbound courses. Occasionally, there is an altitude and height conversion table. For an ILS approach, the height of certain point equals to the altitude minuses the runway threshold elevation. Because the elevation of runway 18R is 115 feet, the LG IAF altitude is 3 070 feet and its height is 2 955 feet (item 18).. Profile View The profile view displays descent path, facilities and minimum altitudes in feet MSL. On Jeppesen charts, an additional height is shown in parentheses and it can be either a height above the threshold (HA1) elevation or height above the airport (HAA) elevation. The HAT is measured from the threshold elevation of the runway served by the approach, while the HAA is measured from the airport elevation. On the profile view of Jeppesen charts, HAT values are presented in the parentheses when a runway threshold elevation is given. If the runway threshold elevation is not given, the numbers in parentheses represent HAA. For CAPITAL approach, pilot should descend from 3 070 feet MSL to 1 920 feet MSL along the outbound course of030° until 08.5 ILG if the aircraft belongs to category Cor category D (item 21). After completing base turn, and when ;rou established on the inbound course, you must keep the minimum altitude of 1 920 feet and intercept the glide slope, then descend along the final approach segment (item 22). Pilot could use the DME-altitude relationship table shown on the profile view to keep the glide path if a NDB or LOC (when GS failures) approach is being implemented (item 20). For example, the minimum altitude should be 1 060 feet when you descend to DME 3.0 nautical miles ILG. Landing Minimums
The landing minimums section is an extremely important part of an approach chart. Minimums have been established for each approach at a given airport and can vary from runway to runway. Factors which affect these minimums include the type of approach equipment installed, runway lighting and obstructions in the approach or missed approach path. Landing minimums are also affected by the equipment on board your aircraft and your approach speed. Approach minimums contain both minimum visibility and minimum altitude requirements. 1) Visibility Requirements. To continue your approach past the missed approach point, the visibility must be equal to or greater than that listed on the approach chart. In addition, you must be able to clearly identify at least one of the above mentioned visual references for the intended runway. 178
\\ben the visibility is expressed in meters of VIS, it is usuall) a prevailing visibility that is ~·'"' -:~d
by an accredited observer (tower or weather personnel). When the visibility is expressed in
-=·=:s ofRVR, it is determined through the use of runway visual range (RVR) equipment. On the .:..:...,:_ Jeppesen provides both the RVR and the VIS in the approach minimums section. For !:U.-:lple, the minimum visibility is RVR 600 meters or VIS 800 meters when you implement an full C5 approach (item 33). 2) Minimum Descent Requirements. The descent limits shown in the minimums section -::~ate
bow low you are permitted to descend in an attempt to identify the required visual
--::;;rences. This can either be a decision height (DH) or a minimum descent height (MDH) :-:pending on the type of approach. For precision approaches, the point where you must make the :;;dsion to continue the approach or execute a missed approach is referred to as DA (or DR) .,em 32). Jeppesen refers to this MSL altitude as the decision altitude or DA. The figure in :arentheses on Jeppesen charts is the height above touchdown (HAT) if the runway threshold -::evation is given on the profile view. For the ILS DME runway 18R approach at CAPITAL, the '.:-west MSL altitude you can descend to is 318 feet, which equals to 203 feet height above the :ouchdown zone elevation. For nonprecisions, the point where you make a decision to continue ~pproach or execute a missed approach procedure is defmed as MDA, which referred to the mean sea level. Jepessen also present MDH
mparentheses if the runway elevation is given.
For
CAPITAL, the MDA is 420 feet and the MDH is 305 feet when you are executing a NOB DME approach. When the ILS glide slope is inoperative, the procedure becomes a nonprecision, localizer approach. Nonprecision approaches use a minimum descent altitude 1\tiDA. Upon crossing the final approach fix or
st~p
down fix, as appropriate, you descend to the MDA. You can remain ryf thi!:
altitude until you reach the missed approach point However, you may not descend below the MDA unless the visual requirements can be mel In this case, the missed approach point is detennined by LMM and the MDA ofLOC approach is 420 feet (item 24). The conversion table at the bottom of the Jeppesen charts also provides the glide slope angle and a recommended rate of descent to maintain the glide slope during an ILS approach (item 35). For example, if your groundspeed is 140 knots, your rate of descent shouid be 753 feet per minute to follow the glide slope. Jeppesen charts also give the landing minimum criteria of visual circling approach in the landing minimums table. In this case, the minimum visibility of circle-to-land is 3 600 meters the MDA is 820 feet (item 34).
anc
AIRPORT CHARTS Jeppesen usually provides a full-page airport diagram for selected airport to assist the movement of ground traffic where complex runway and taxiway configurations exist. If the surface of the airport is too complex, the airport chart may be divided into two pages. No :1atter hO\\
tl.'l:t!
7C;
pages are there, a Jepp~:cn ai::port chart usually consists of heading section, plan view, additional runway infounation and take-off minimums.
Heading Section The heading section (,f the Jeppesen airport chart identifies the airport, its location, elevation, chart effective date, and outbouno communication frequencies. You will notice many similarities between this section and the heading section of a Jeppesen approach chart (see Figure 6-14). CAPITAL airport geographic location is given in the fonnat of latitude and longitude coordinates. The lal~tude a'1d longitude coordinates of the official airport location are N40 04.4 and E116 35.7 (item l). The airport elevation and the chart effective date are included on the Jeppesen airport chart. In tlus case, the elevation of the CAPITAL airport is 115 feet (item 2), and the chart ·'!ffective dat~.: is 16 May, 2003 (item 3). The communications section (item 4) lists the frequencies in the order they are nonnally used when you depart the airpon. In this case, you frrst contact Ground Control on the frequency of 121.7 from 1201 to 2400, but from 0001 to 1200, you should contact Ground Control on the frequency of 121.9 when you are being west or 121.7 when you are being east. When you are being at the hold point outside the runway, you should contact Tower on 118.1, and then followed by 119.7 Departure Control.
Plan View The plan view portrays an overhead view of the airport. Its purpose is to provide you with infonnation about the airport, such as its runways and lighting systems (Figure 6-14). Jeppesen airport charts usually list the elevation of each end of the runway. This alJows you to estimate the average runway slope or gradient. For instance, the threshold elevation of runway 18R
is 115 feet (item 5), and at other end of this runway, the threshold elevation is 108 feet, so, the gradient of runway 18R is about 0.0667 %. Jeppesen shows not only the width of the stopway (item
6) associated with a runway, but also the runway length (item 7). In this case, the length of runway 18R is 3 200 meteN, and runway 18L 3 800 meters. The airport reference point, or ARP, (item 8) is where the official latitude and longitude coordinates are derived.
The location of the airport's control tower (item 9) may be shown on the plan view, along with the Ioca1ion of aprons (item 10). Runway numbers (item 11) are located at the end of each runway. Jeppesen also I:sts the actual magnetic direction of the runway (item 12). This information allowf. you to make a final cross-check of the magnetic compass and heading indicator orior to flight. On the upper rillht~hand comer ofthe chart, tlle magnetic variation is shown (item 13). This infonnation is usually used to depict the runway direction. At the bottom of the chart, there is a scale of the chart (item 15), which may be used to measure the length of two points. Occasionally, 5ome important notes about the airport are also shown at the bottom of the plan view. In this case, ''DO NOT MISTAKE LIGHTED ROAD FOR RUNWAY'' reminds that some lighted road around the airport may be thought to be the runway during night approach (item 14). 180
ZBAA/PEK ~ I Apt Elev
D
\
115'
BEIJING \PR OF CHINA
: :.JEPPESEN 16 MAY 03
I
(@])
~
N~O
CAPITAL
OU Ell6 35.7
f AJIS
119.7
/
I
191'60..
' APRON7
l!)lttr
WESI \ ----~----; t
-;-
121.9 ll
1.
~
~ Ground (0001 • 1100) J \
:" c I W2
121.7 I 1
J
I
11201. 2•001
l 1
---------
t
19n0m
1
FOil PARKING I POSITIONS '\
I . I
SEE 10·91
r----------- -r~-
,-------121.7~ EASI
'Ground
1--------
Let• 0
A9
E5 !'"
\
~\)
A
£6 Elev 98'
00 NOT MISTAKE
LIGHTED ROAD FOR RUNWAY
A
1"' 6Ctr. Stop\l.rly
0lctr
Figure 6-14 Beading Section and Plan View of Airport Chart
181
Additional Runway Information Runway and approach lighting systems, as well as PAPI installations, arc shown on Jeppesen, and which includes tllis intbrmation in the additional runway information section. This section contains other data, such as grooved runways, RVR equipmen4 usable runway lengths and runway widths (Figure 6-15). ~.JEPPESEN
ZBAA/PEK
16MAYOJ
BEIJING, PR OF CHINA
(10-9A)
CAPITAL
~ Rwy 36!t 1$ approv-.d for CAT U operatrons, !:podol airct"ew end odl cerllf1cation r•quired.
Rwy• 18R
&
361l rlght·bend c ircuit.
ADDITIONAl RUNWAY INfORMATIO~SABLE UNGTHS I-LANDING RWV I / ...., Throahold Glide Slopo TAI
0
......----~
1BEVON~~ ~~~
l
o 1ur ·E(, es 0
18R
H$T·E2,
~3
HIR~aOHIAlS SFL TOZ PAPI·l 3 .0° 0 nvR 36l HIRLO ClO HIAlS PAPI·l(3.0"} ORVR
/94&5' 711Sm
I
W IDTl1 197' 6Dm
+ n 164' Slim
'P'I''7
00 while opacing 60"' 30m 0HST·W4, WS OHST·WI, Wl
l t-....
2 TUtti lno Of"
;~ 8
3' ''"" 0 o ....
TAKE· Off Rwy tBl/3611 LV,. must bo in for~
_,
HIIU0"4C:l
I
Ill endRCU4
tvt700m
l
IMI250m
ltVI
250m
-~·
.,
"II llwy1 Nit 4 0AYO"\~
R'o/lt~OO,
•W
tMI.100m VISI600m
I
""m
Figure 6-15 Runway Information and Take-off Minimums
182
For CAPITAL airport, its ruJlway lighting system consists of HW.L and CL (item 1). The ::-;.::e of the CL system is 60 meters. The approach lighting system of four direction of two runway~ IS ~·IALs (item 2). The light space of runway 18L and runwa" 36R is 15 meters with white colort :n: le runway 18R and 36 L is 30 meters with the same color. The landing useable length of rLJnwa; ;p after glide slope is J 488 meters or 11444 feet (item 3). The width of runway 36R/1 81 is 60 r::eters (item 4).
-3.ke-off and Alternate Minimums CAAC has estahlishect airport operation zules which provide tak......off minimums •or all
.:1·:nmercial operated aircrafl.. Although legal, it is unwise to initiate a take-off in weathe1 conditions -"'at would keep a commercial flight g,LOUilO
ENROUTE CHARTS This section presents an overview of the idonnation and symbo!cg) contained on enroute and area charts. Enroute charts are primarily usea for IFR cross-countrj flights and contain essential 183
information that helps you keep track of your position, as well as maintain obstacle clearance and navigation signal reception. Area charts portray more detail than enroute charts and are primarily used during the transition to or from the enroute structure. In some cases, the symbols appear in the margin with an explanation in the accompanying text For China airways, 6 300 meters MSL is the altitude that separates the national airway system from Class A airspace. Therefore, it is a convenient place to establish the division between the low and high altitude airway structures. Airways located below 6 300 meters MSL are depicted on low altitude enroute charts and those at or above 6 300 meters MSL are shown on high altitude enroute charts. Jeppesen enroute charts of China combined the low altitude and the high altitude airways on a sheet of chart. This section concentrates on Jeppesen high/low enroute charts, since these charts display vast amounts of information about the airways, routes of flight, radio facilities used for enroute navigation, identification of instrument fixes, airport information, communications available, altitudes that guarantee proper reception of navigation signals, and terrain clearance. Front Panel
At the top of the Jeppesen front panel, the name of the chart, as well as the series number and the scale are presented. In this case, CH (HIL) 2 is the naine of CHINA IDGHILOW ALTITUDE ENROUTE CHARTS with a scale of 1 inch equals to 80 nautical miles (Figure 6-16). Following the name of the chart, Jeppesen presents a specification of airways, routes and airspaces on the chart and some other notes of flying. On the middle of the Jeppesen front panel, the limits and classifications of designated airspace table is given. For example, the vertical separation from the ground to FL 6 100 meters is the former USSR lower airspace (item 5). Usually, there is a specification of revision data behind the table of limits and classifications of designated airspace (item 6). Jeppesen portrays the area covered by each enroute chart with squares on the front panel, which contains valuable information concerning the use of the chart. The effective date at the top (item 8) tells you when the old chart becomes obsolete for navigation and the information on the new chart becomes effective. A square within the bold outline is used to indicate the chart you are holding, as well as its coverage area. The locations of major cities are included to help you find the appropriate chart quickly. Jeppesen uses a bold city name and a blue shading to show where area charts are available (item 9). Time zone boundaries are included on Jeppesen charts. Jeppesen includes the formula to convert both standard and daylight time to Coordinated Universal Time on the front panel (item 10). Navigation Aids and Communications
On the Jeppesen charts for China, there are mainly four types of navaids: VORIDME, NDB, as well as ILS (Figure 6-17). 184
Flying outside of ATS routs wltflln P R of China, D' R of t
CLASS
MANDALAY SECTOR :UNDEP.L!ES YANGON FIR) MONGOUA FIRs
.
GND· FL200
.
Fl118 · FL 397 FL.WWm·FL/2/00m GNO • FL200 GND. FL 6100m
• CU\SS
FORMER .USSR UPPER AIRSPACE FORMER USSR FIRs
.
.
~
UMITS FL200 • UNL
PL 6:00m • UNL FL 39- FL 397
-
FLI200m·FL12!00r.t
FORMER USSR LOWER AIRSPACE • Airspace classification not spe<:if
~EV1SION DATA CHART C.H(HIL) 1 5 MAR 93 Mullan VOR frequency changed. Numerous radio alds Within Cluna commissioned/decommissionedlchanQed. Pingzhou VOA deoomm1ssioned. ATS sySIAm and ·~~·ictive airspace within China revised.
CHART CH(HIL) 2
5 MAR 93 Pyongyang VOADME ident changed. Vledivoslol< Loe&tors commissioned. Numerous rad1o a•ds within China commfsslonedldecomm!sslo$clldlanged. Pingzl\Ou VOA decommissioned. ATS system and restrictive airspace within China revised.
Figure 6-16 Front Panel ofEnroute Chart 185
\
'
116
35m
\
.
~.:u~~
·1'!0- --. ·--. -+·
., .... --• . I), •• -.
-'"--·- .. · ~
llz ·•
.... j
.. 3•*)""..~...;!• ....
' "".!.
....
1.25
3sn.. ~ -- · ·
I
\
r ----- .·-- ' \ . ···--· Figure 6-17 Enroute Chart
186
A VOR is represented as a compass rose oriented to magnetic north. The center of the compass
-0se shows the location of the VOR station. Jeppesen charts use the symbol itself to indicate a VOR :'acility and use a serrated circle to portray Dl'v1E facilities. A collocated VOR and DME is called a \ 'OR!Dl'v1E. Since VORIDME is functionally identical for civil aircraft, Jeppesen uses a single symbol to indicate this type of facility. The information in a VOR or VORIDME facility box provides you with the facility's name, frequency, and identifier (both three-letter and Morse code). The letter ''D" preceding the frequency in the Jeppesen excerpt indicates DME information is available (item 1). The nondirectional radio beacon (NDB) is a low frequency navaid used for instrument approaches, as well as for enroute navigation. On Jeppesen charts, a nondirectional radio beacon is shown as a circle of dots (item 2). The arrow extending out of the top is aligned with magnetic north, which makes it possible to measure the magnetic bearing with a plotter. This symbol is also similar to the ones used to depict compass locators. On Jeppesen charts, they are shown only when the facility provides an enroute function. The facility box for an NDB includes the name, frequency, and identification code. Jeppesen often groups NDB information with an adjacent VORIDME if it has the same name (item 3). Jeppesen shows the availability of ILS approaches with a locaJjzer symbol. On the chart, the front course of an ILS is depicted an arrow with the right triangle filled short lines (item 4). The information ofiLS is shown on the ILS approach chart. The boundary of an air traffic control center (ACC) is designated by a line, along with the name of the controlling center. If the control area is not divided into several sectors, Jeppesen uses only one rectangle to present the ACC's name, communication frequency, as well as the service time (item 7). In order to provide adequate communications coverage throughout the area served by certain control center, the area with heavy traffic is usually divided into several sectors. If the control area is divided into several sectors, Jeppesen lists the name, frequency, and the service time of each sector respectively. For example, the frequency of south sector of Beijing control is 132.70 MHz. In addition, jeppesen uses a thin-line box to provide the communication frequency of the approach control office (item 9). Pilots could use the frequencies shown in the ellipse box to listen weather information (item 8) during flight In China, there are only two such stations situated at Beijing and Guangzbou. The asterisk preceding the navaid or communication frequency indicates this service is available on a part-time basis (item 7).
Airways Airways on Jeppesen charts for China are marked with a letter and a series of number. The first letter should be A,B or G which means that foreign countries' aircrafts may operate on the airway. The width of an airway is normally 4 nautical miles on each side of its centerline. This provides a total airway width of 8 nautical miles (Figure 6-17). All distances on IFR Jeppesen enroute charts are expressed in nautical miles and kilometers, 1R7
and nautical miles usually situates above or prior to kilometers. On Jeppesen charts for China, a number enclosed within an outlined box indicates total distance between navaids and/or compulsory reporting points. A number that is not enclosed in an outlined box indicates the distance between compulsory reporting points, intersections, navigation aids, or airway direction break points.
An airway break point is shown on a chart by a small "x" on the airway. Generally, this symbol indicates a point on the airway where the course changes direction and where an intersection is not designated. Intersections are checkpoints along an airway that provide a means for you and ATC to check the progress of a flight. They are often located at the points where the airway turns or where you need a positive means of establishing your position. Intersections are given five~ letter names above the latitude and longitude (item 11 ). Intersections are designated as either compulsory or noncompulsory reporting points. A compulsory reporting point is identified by a solid triangle. In a non radar environment, you are required to make a position report when you pass over this point. Noncompulsory reporting points are identified by open triangles, and position reports are not required, unless requested by ATC. For the convenience of flight, Jeppesen enroute charts for China present four types of altitude along airway. They are maximum authorized altitude (MAA), flight level (FL), minimum safe altitude (MSA) and minimum off-route altitude (MORA). Occasionally, it is necessary to establish a MAA for a route segment. MAA is the highest altitude you can fly based on the transmitting distance of VOR or VORIDME stations which use the same frequency. The MAA is established when the distance between two stations using the same frequency is such that both signals can be received at the same time, giving you an unreliable navigation signal. An MAA is shown with the letters "MAA" followed by the altitude. In the excerpt, MAA FL394 (item 15) above FL 12 000 m means that the maximum authorized altitude is 39 400 feet, which equals to 12 000 meters. It is for the convenience of ATC to do so. The flight level (FL) is usually the turbo~powered aircrafts cruising altitude. The FL for the route in this excerpt is 29 500 feet, which equals to 9 000 meters (item 12). In practical operation, pilots must comply with the ATC clearance. The minimum safe altitude (MSA) is shown for some route segments. On Jeppesen charts, it is identified by the letter ''T", which follows the altitude number. ln the following excerpt, the MSA for the route segment from BAOTOU to LIANGCHENG is 9 700 feet or 2 937 meters MSL (item 13). When you are not following an airway such as during a direct segment of an IFR flight, you are responsible for determining the minimum safe altitude. Basically, you must remain at least 400 meters above the highest obstacle within a horizontal distance of 25 kilometers from the course to be flown. In designated mountainous areas, the minimum altitude is increased to 600 meters and the distance from the course remains the same. You should also consider the range limitations of the navigation facilities and communications requirements when you establish your minimum altitude. The last altitude at the bottom of the altitude series is MORA, which is the abbreviation of minimum off~route altitude (item 14). The MORA is the MSA within the segment from the middle
188
:vint to the end of the route. In this case, the MORA is 10 000 feet or 3 100 meters. ~
rports and Airspaces Airports are divided into two basic categories- those with a published instrument approach
?rocedure and those without such a procedure. If an airport has a published instrument approach, : eppesen provides basic information about each airport. The basic information includes the airport a:1d city name in capital letters, as well as the frequencies and identifiers ofNDB navaids located at :he terminal. For example, Wusu TAIYUAN has set up instrument approach procedures, and its airport elevation is 2 566 feet or 782 meters. There are altogether three NDB navaids with operation frequencies of 228, 413 and 373 kHz, and their identifiers are B, C and BG separately (item 5) (Figure 6-17). Above FL 600 meters, the airspace is controlled airspace in China. Aircrafts may operate under VFR or IFR below FL 6 000 meters, while the air carrier must operate under IFR at or above the FL 6 300 meters. Special use airspace is designated and identified on enroute charts as either prohibited, restricted, or danger areas. On Jeppesen charts, all special use airspace is outlined by a green border. Information concerning each area is listed in or near the airspace, or it can be found on a chart panel. Information of the special use airspace usually includes its serial number, the upper and lower limit The capital letter enclosed in the parentheses of the serial number indicates the type of the special airspace, ''P" represents prohibited area, "R". represents restricted area and "D" represents restricted area. For example, item 10 on the following excerpt is a prohibited area, which extends from the ground to aloof.
Area Charts On Jeppesen enroute charts, a heavy blue dashed line signifies that an area chart is published for that terminal area. The information within the outlined area is normally limited to that necessary for through flights. If your departure or destination airport is within the boundary, you should refer to the appropriate area chart for complete information. Most of the symbology on area charts is identical to that of the enroute charts. Because of the scale used, more detail is possible, and readability is improved. In this case, Beijing terminal is enclosed with a heavy dashed line and it means an area chart has been depicted (Figure 6-17).
DEPARTURE AND ARRIVAL CHARTS Departure and arrival charts are published to help simplify complex clearances, reduce frequency congestion, and control the flow of traffic around an airport In some cases, they help reduce fuel consumption and often include noise abatement procedures. The standard instrument departure (SID) is used after take-off to provide a transition between the airport and the enroute structure. The standard terminal arrival route (STAR) performs the opposite function. It provides a standard method for departing the enroute structure and navigating to your destination. STAR usually terminate with an instrument or visual approach procedure. This section analyzes both 1R9
SID and STAR charts to help you become better acquainted with the symbols and information they contam. Jeppesen publishes SIDs and STARs for airports with procedures authorized by the Civil Aviation Administration of China (CAAC). Jeppesen includes the applicable departure and arrival charts in the basic approach chart subscription and these charts are filed with the airport's approach charts. When you accept a SID or STAR in a clearance, or you file for one in your flight plan, you are required to have a graphic or, at least, a textual description of the procedure in your possession. If you don't have the appropriate charts or don't want to use them, you should include the notation "NO SID -NO STAR" in the remarks section of your lFR flight plan. This advises A TC not to issue a clearance which contains one of these procedures. To illustrate how these procedures can be used to simplify a complex clearance and reduce frequency congestion, consider the following departure clearance issued to a pilot who was about to depart from CAPITAL, BEIJING, "AIR China 4102, cleared to Chengdu via VM 12 departure, flight planned route, FL 9 000 meters, aquawk A21 01 ".
Standard Instrument Departure Any clearance you are issued that contains SID takes precedence over any IFR departure procedures published for the airport. Since you are obligated to comply with the provisions listed for the SID, you must ensure your aircraft is capable of achieving the performance requirements. Some SIDs requires you to cross a ftx at or above a specified altitude. If the climb performance of your aircraft does not allow you to reach the altitude by the fix, you can't use the SID. Your responsibility as pilot-in-command is to review each SID, make sure your aircraft can comply with the procedures, and refuse any SID that is beyond the limits of your aircraft. CAAC disseminates pilots navigation SIDs by now. Pilot navigation SIDs are designed to allow you to navigate along a specified route with minimal communications with A TC. The SIDs usually contain an initial set of instructions that apply to an aircraft followed by one or more transition routes that require you to navigate to the appropriate fix within the enroute structure. The symbols used on Jeppesen SIDs are very similar to those used on other charts. Jeppesen SIDs include a textual description of the initial take-off and transition procedures, and a plan view of the routing. In some cases, a textual description may not be provided for a simple transition (Figure 6-18). At the top of the chart, Jeppesen usually lists the airport name served by the procedure (item I), the effective date of the chart (item 2), as well as the name of the chart (item 3) and the city name (item 4). In this case, it is CAPITAL airport in BEIJING, PROF CHINA. The effective date of this chart is 24 January 2003, and this chart is a pilot nav SID. The airport elevation (item 5) is shown at the upper left-hand comer of the plan view, which could be used to help pilot calculate the height of the airplane because the altimeter displays altitude. For instance, when the airplane takes off from runway 36L, it must climb to altitude 1 970 feet at 190
ZBAA/PEK
CAPITAL~
~
D
a~
Trans level: FL 118
Apt Elev
B
115'
tI
::.JEPPESEN 714 JAN o3
(1 o-3A)
BEIJING, P& OF CHINA
II~
11 ~ ll:B
Trans all : 9850'
~
10830' • QNH 1031 hPl!l or above 8860' • QNH 979 hPa or below
-~~~
VM 10 VM 20 VM 110 VM 120 VYK 1D VYK 20 VYK 110 VYK 120 RWY 18l RWY 36l RWY 18R RWY 36R
MSA
PEK VOR
J
Ill
t
I t.!.l E.'!'!:!<
FT/METER CONVERSION QNH
I
~AWAHGZHUANGl
660' • 200m 1640' 500m 1970' 600m 4930' 1500m 6890' 2100m 8860' 2700m 9850' 3000m 10830' 3300m
*489 YK
I
N39 lt.S E116 34.3
CAT
C, 0
Ill ./
~
r
SHIGEZMUANGl
*28om
H39
IS•.OE06 54.0
VM 10, 20, 110, 120
At or above FL236 CAT 8 At FL 138 CAT C, 0 below
Fl236. CAT B below fl138 & CAT A
FL CONVERSION
Fl118 Fll38 FL 148 FL 187 FL 197 Fl236
1139 11.5 E116 34.3
Fl3600m Fl4200m Fl4500m Fl5700m Fl6000m Fl7200m
At or above FL197 CAT8
At Fl138 Gnd speed - KT
75 100 150 200 250 300 5•At 304' per NM 380 506 760 1013 1266 1519 4.6% 280' per NM 349 466 699 932 1165 1398
CHANCES:
o..wangrhuang V0R &
CAT A & acft
below FLI38
At enroute Al T
NOB coordin"""-
Figure 6-18 Standard Instrument Departure Cbart
191
distance of7 nautical miles to PEK VOR, the height of this point is 1 855 feet. For the convenience of pilot correcting altimeter, Jeppesen lists Transition Level (TL) and Transition Altitude (TA) at the top of the plan view (item 6). If QNH greater than 979 hPa and less than 1 031 hPa, pilot must not correct altimeter to 1 013 hPa until it indicates 9 850 feet altitude. The MSA of different sectors within 25 nautical miles to PEK VOR is depicted at the upper right-hand corer of the plan view (item 7), which is same of the approach chart The runway number served by the SIDs is listed at the top of the plan view (item 8). For CAPITAL SID, when the airplane takes off from runway 36R and departures to south, the SID may be VM 120 or VYK 120, while if the airplane takes off from runway 36L, the SID may be VM 20 orVYK2D. The plan view of the SID mainly depicts runways served by different departure routes, as well as navaids and intersections. Besides these factors, altitudes, magnetic course, mileage between two intersections or navaids and sometimes the climb gradient of certain segment are portrayed on the graphic. Navaids are similar to those we discussed in other charts, for example, the frequency of HUAIRONG VOR/O:ME is 113.6 MHz with an identifier ofHUR, its geographical coordinates are north latitude 40 degrees 19.8 minutes and east longitude 116 degrees 44.9 minutes (item 9). Jeppesen SID provides the latitude and longitude coordinates of intersections (item 10), mileage break points to certain navigation facility and the outbound course. In this case, the mileage from XILIUHETUN to SHIGEZHUANG is 39 nautical miles (item 11), and the outbound magnetic course is 184° (item 12). Because of the large area covered, most SIDs are not usually drawn to scale. When this is the case, the notation ''NOT TO SCALE" is printed on the chart (item 13). Typically, when cleared to departure to SHIGEZHUANG via VM 120, pilots are expected to maintain the runway heading 359° that corresponds with the extended runway centerline and drift angle should not be applied. The initial take-off procedure applies to all runways. The graphic, or plan view of the departure route portrays the radial and altitude from CAPITAL to the initial tum point (item 14). On Jeppesen charts, this route is shown by a bold line. Thin lines are used to indicate the appropriate radial for navigating or identifying fixes. The actual mileage between a given runway and the intersection varies with aircraft performance and pilot technique. Therefore, Jeppesen includes the direct distance of 13 n.m. from the tum point to the intersection of OME 3 n.m. along HUAIROU radial 212° (item 15). After turning right, the airplane must fly to XILIUHETUN at or above 4 930 feet MSL along 206° (item 16). If your planned route allows you to follow one of the transitions, it is usually to your benefit to file for the transition. For example, suppose your route of flight takes you over the SHIGEZHUANG VORIDME. In this case, you can include the SHIGEZHUANG transition in your flight plan. The distance from XILIUHETUN to the SIUGEZHUANG VORIDME is 39 n.m., and the course follows the 184° radial from XILIUHETIJN (184° outbound). Notice that there are two different way points may transition via SlllGEZHUANG, one is CG and another is BTO. According to airplane's category and the departure direction, Jeppesen lists the minimum altitude o: the airplane via transition SlllGEZHUANG in tbe rectangle (item 17). In this case, the minimun: 192
altitude of category C and D airplanes must be at or above FL187 (5 700 meters) when the airplane departures to CG, while category A and other aircrafts bellow FL148 and at the enroute altitude filed in the flight plan (item 18). When you file for this transition, the first part of your routing should list the ATC code VM. This tells ATC you plan to fly the VM Departure and the SHIGEZHUANG transition. Listing the code exactly as it appears on the SID helps ATC enter it into the computer and reduce the time required to process your flight plan. The remainder of your route, starting at SHIGEZHUANG, is entered following this code. For the convenience of converting meter to feet, Jeppesen lists a feet and meter conversion table at the left of the chart (item 19). For example, if you are cleared to climb to altitude 5 700 meters via SHIGEZHUANG, you could easily determine that the altitude is FL 18 700 feet from the table.
In order to climb to the minimum altitude of 4 930 feet, Jeppesen gives out a ground speed (GS) and ratio of climb (R.C) relationship table at the lower left-hand corner of the plan view (item 20). If you are cleared to departure from runway 18R, because the minimum climb gradient is 4.6% from DK NDB to WF NDB, you must keep at least the RC of 699 feet per minute with GS 150 knots. Standard Terminal Arrival Route The standard terminal arrival route (STAR) uses symbols similar to those found on a SID chart. Since the procedure may begin at more than one enroute fix, several transitions may join into one common arrival route. The arrival routes normally terminate at an initial approach fix (IAF). On the accompanying CAPITAL arrival chart, four transitions are portrayed from DAWANGZHUANG VORIDME, HUAllAI and GUBEIKOU NDBs. VYK lA and LR 1A converge at HUAIROU VORIDME, while VYK 3A and KM lA coverage at the intersection ofDME 16 n.m. and QDR 277° from HUAIROU (Figure 6-19). Like SIDs, STARs include the name of the airport served (item 1) and the name of the procedure (item 2) near the top of the chart. The LR 1A transition (item 3) begins at the GUBEIKOU NDB and follows the magnetic course of 277° to the HUAIROU VOR/D:ME. The minimum altitude of approach for this route segment is 4 930 feet MSL (item 4), and the distance is 25 n.m.. The altitude that the airplane descends from enroute altitude to GUBEIKOU is different, and it yields to the category of the airplane. Category B, C and D airplanes should descend to certain FL between FL118 and FL148 by ATC (item 5). Category A airplane and other aircrafts should keep their enroute altitude below FL118. The arrival route VYK lA begins from DAWANGZHUANG and ends at HUAIROU, it is divided into two segments by the hold fix which locates at D:ME 25 from BEIJING VORID:ME along QDR 187° (item 6). The outbound course for the first segment is 007° (item 7), and the inbound course for the second segment is 016° (item 8) to HUAIROU. The first segment is 27 n.m. long and the second segment is altogether 42 n.m.. If you received an approach clearance along 193
ZBAA/PEK
::JEPPESEN
"
CAPITAL~
2~JAN03 ~
Ll
All Sel. hPa *ATIS
Apt Eft1v
127.6
115'
Trans level: FL 118 Trans all: 9850' 10830' · QNH I 031 hPo or above 8860' • QNH 979 hPo or below
KM lA, LR lA
r:;; GUBEIKOU
VYK lA, VYK 3A
I •2~
RWYS 18l/R ARRIVAlS
FLUS & Fl118 CAT A & aclt
below FL 118
(IAfJ
038 HUll N40 20. S
'
i~JOJ'!.,2o \ 09J"-D.J4 ~
0 on
7880 X -
H\JAil.AI :-1
*360 !~
X
4
X -R277""--013 SZY
...,, X
H40 18.2 £116 21.6
~~At "'
HUll
1
~SHAZJYING1
~'-~-~-!_ H~R I
'? V': ~
N40 19.8 E116 44.9
[At 4930']
(. . . .) r
Between
. ,...!.1~:.~. ~~~-~
Fl187 & Fl148
N40 06. 1 E116 27.7
CAT B below FL138 & CAT A
/
Ill
q
~ ~ ~
~ PROHIBITED A~SA ZB(P l·OOI
~
Fl5700m Fl4500m Fl4200m Fl3900m Fl3600m
FT/METER CONVERSION ONH
3300m 3000m 2700m 2400m 2100m !BOOm ISOOm
~ ...
~'P' ~ ~ ~
~~..<"JW'~~~ff41
025 PEK N39 38.0 Elt6 3S.S
..,.
~
0
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II
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~x.4,f ~ ~
DAWANGZHUANGl
Fl CONVERSION
Oil itif36.0
r/$?~~#1'~~ ~
North arrival sector : Available below 5910' operation hours by ATC.
VYK r~,,_112.7 --- -·I ·~~~ .!~ I N39 ll.S Ell6 34.3
-o
X
-
D29 PEK ~
Ill
1111
Hl9 ll.S E116 lU
CAT 8, C & 0 Between
Fll87 & FL 148 By ATC. AI
Fl 138
or ar Fl I 28 CAT A & acft below fll ~8 At enroute Al T
Figure 6-19 Standard Terminal Arrival Chart
194
'u
BEIJING ;:;-1 14.7 P~K I
1""
~
r-:0,..-0-evi_a_li_on_ w_e-51.., of SZY R-180 not permitted.
10830' 9850' 8860' 7880' 6890' 5910' 4930'
(IAfl IIJAIROU~
"930')
v-
·CAT 8, C & D
Fl187 Fl148 Fl138 Fll28 FLIIS
Al T
/
N40 23 6 EllS 29 S
At enroute ALT
enroute
~
7910']
-/K;;f 1A""'( X ~ X ~
At
0 II HUll N40 20.0 E116 24.0
O:U HUll
EllS SS.2
l
N40 38.0 Ell7 05.0 CAT B, C & 0 Between
I
I
J.!
..
~
NOT TO SCALE
VYK lA, you frrst descend to 6 890 feet to D25 PEK, then turn right and descend to 5 910 feet to Dl8 HUR (item 9). If you are cleared to hold at D25 PEK, the minimum hold altitude of this procedure is 6 890 feet, and the coverage of the procedure is between DME 25 n.m. and 29 n.m. to PEK (item 10). Since the minimum hold altitude of another two hold procedures is not shown on the chart, you should maintain enroute altitude until you are assigned a lower hold altitude by ATC (item 11). The textual explanation at the left side of the chart is a description of the VYK 3A arrival route (item 12). If you are cleared to fly to AHAZIYING along the VYK 3A arrival route, you must keep in mind that you can't deviate to the west side ofSZY Rl80°, because the BEUING prohibited area is located at the west side of szy R180°. 1f the enroute portion of your flight ends at the DAWANGZHUANG VOR/DME, you shopld add the code VYK to the end of the route description in your IFR flight plan. There are two arrival routes after DA WANGZHUANG, you can't file VYK l A or VYK 3A on your flight plan because the arrival route is given by the ATC upon arrival conditions.
'
195
CHAPTER 7 EMERGENCY, PHYSIOLOGY AND CREW RESOURCE MANAGEMENT SECTION A FLIGHT EMERGENCY AND HAZARDS The Pilot/Controller Glossary divides emergencies into two categories: distress and urgency. Distress is a condition of being threatened by serious and/or imminent danger and of requiring immediate assistance. Distress conditions include fire, mechanical failure or structural damage. An urgency condition is one of being concerned about safety and of requiring timely but not immediate assistance. At least an urgency condition exists the moment a pilot becomes doubtful about position, fuel endurance, weather or any other conditions that could adversely affect the safety of flight. A pilot should declare an emergency when either an urgency or a distress condition exists. Pilots who become apprehensive for their safety for any reason should request assistance immediately. Ready and willing help is available in the form of radio, radar, direction finding stations and other aircraft. Delay causes accidents and costs lives. Safety is not a luxury! Take action!
TRANSPONDER EMERGENCY OPERATION When a distress or urgency condition exists, the pilot should set the radar beacon transponder to code 7700.If an aircraft is being hijacked or illegally interfered with, the pilot can alert ATC to that fact by setting the transponder to code 7500. If an ai.rt;raft has experienced a two-way communications radio failure, the pilot should set the transponder to code 7600. The pilot should also conform to the radio failure procedures (IFR operations: Two-way radio communications failure). In order to avoid false alarms, pilots should take care not to inadvertently switch through codes 7500, 7600 and 7700 when changing the transponder.
DISTRESS AND URGENCY COMMUNICATIONS A pilot who encounters a distress or urgency condition can obtain assistance simply by contacting the air traffic facility or other agency in whose area of responsibility the aircraft is operating, stating the nature of the difficulty, pilot's intentions and assistance desires. Distress and urgency communications procedures are prescribed by the International Civil Aviation 196
Organization (ICAO), however, and have decided advantages over the informal procedure described above. Distress and urgency communications procedures discussed in the following paragraphs related to the use of air ground voice communications. A. The initial communication and, if considered necessary, any subsequent transmissions by an aircraft in distress should begin with the signal MAYDAY, preferably repeated three times. The signal PAN-PAN should be used in the same manner for an urgency condition. B. Distress communications have absolute priority over aU other communications, and the word MAYDAY commands radio silence on the frequency in use. Urgency communications have priority over aU other communications except distress and the word PAN-PAN warns other stations not to interfere will urgency transmissions. C. Normally, the station addressed will be the air traffic facility or other agency providing air traffic services on the frequency in use at the time. If the pilot is not communicating and receiving services, the station to be called will normally be the air traffic facility or other agency in whose area of responsibility the aircraft is operating on the appropriate assigned frequency. If the station addressed does not respond, or if time or the situation dictates, the distress or urgency message may be broadcast, or a collect call may be used, addressing "Any Station (Tower, Radio, Radar)". D. The station addressed should immediately acknowledge a distress or urgency message, provide assistance, coordinate and direct the activities of assisting facilities, and alert the appropriate search and rescue coordinator if warranted. Responsibility will be transferred to another station only if better handling will result. E. All other stations, aircraft and ground, will continue to listen until it is evident that assistance is being provided. If any station becomes aware that the station being called either has not received a distress or urgency message, or can't communicate with the aircraft in difficulty, it will attempt to contact the aircraft and provide assistance.
OBTAINING EMERGENCY ASSISTANCE A pilot in any distress or urgency condition should immediate take the following action, not necessarily in the order listed, to obtain assistance: A. Climb, if possible, for improved communications, and better radar and direction finding detection. However, it must be understood that unauthorized climb or descent under IFR conditions within controlled airspace is prohibited, except as permitted by CCAR Part 91.3. B. If equipped with a radar beacon transponder: • Continue squawking assigned MODE A/3discrete codeNFR code and MODE C altitude encoding when in radio contact with an air traffic facility or other agency providing air traffic services, unless instructed to do otherwise.
• If unable to immediately establish communications with an air traffic facility/agency, 197
squawk MODE A/3, Code 7700/Emergency and MODE C. C. Transmit a distress or urgency message consisting of as many as necessary of the following elements, preferably in the order listed: • If distress, MAYDAY, MAYDAY, MAYDAY; if urgency PAN-PAN, PAN-PAN, PAN-PAN. • Name of station addressed. • Aircraft identification and type. • Nature of distress or urgency. ·Weather. • Pilots intentions and request. • Present position, and heading; or if lost last known position, time, and heading since that position. • Altitude or flight level. • Fuel remaining in minutes. • Number of people on board. • Any other useful information. After establishing radio contact, comply with advice and instructions received. Cooperate. Do not hesitate to ask questions or clarify instructions when you do not understand or if you can't comply with clearance. Assist the ground station to control communications on the frequency in use. Silence interfering radio stations. Do not change frequency or change to another ground station unless absolutely necessary. If you do, advise the ground station of the new frequency and station name prior to the change, transmitting in the blind if necessary. If two-way communications can't be established on the new .frequency, return immediately to the frequency or station where two-way communications last existed. When in a distress condition with bailout, crash landing or ditching imminent, take the following additional actions to assist search and rescue units: A. Time and circumstances permitting, transmit as many as necessary of the message elements in subparagraph mentioned C and any of the following that you think might be helpful • ELT status. • Visible landmarks. • Aircraft color. • Number of persons on board. • Emergency equipment on board B. Actuate your ELT if the installation permits C. For bailout, and for crash landing or ditching if risk of fire is not a consideration, set your radio for continuous transmission. D. If it becomes necessary to ditch, make every effort to ditch near a surface vessel. E. After a crash landing unless you have good reason to believe that you will not be located by 198
searching aircraft or ground teams, it is best to remain with your aircraft and prepare means for signaling search aircraft.
TWQ-WAY RADIO COMMUNICATIONS FAILURE It is virtually impossible to provide regulations and procedures applicable to all possible situations associated with two-way radio communications failure. During two-way radio communication failure, when confronted by a situation not covered in the regulation, pilots are expected to exercise good judgment in whatever action they elect to take. Should the situation so dictate, they should not be reluctant to use the emergency action contained in CCAR Part 91.3. Whether two-way communications failure constitutes an emergency depends on the circumstances, and in any event, it is a determination made by the pilot. CCAR Part 91.3 authorizes a pilot to deviate from any rule in Subparts A and B to the extent required to meet an emergency.
In the event of two-way radio communications failure, ATC service will be provided on the basis that the pilot is operating in accordance with CCAR Part 91.185. A pilot experiencing two-way communications failure should (unless emergency authority is exercised) comply with CCAR Part 91.185 quoted below: A. General. Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR Shall comply with the rules of this section. B. VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the night under VFR and land as soon as practicable. NOTE: This procedure also applies when two-way radio failure occurs while operating in Class A airspace. The primary objective of this provision in FAR Pad 91.185 is to preclude extended IFR operation in the A TC system in VFR weather conditions. Pilots should recognize that operation under these conditions may unnecessarily as well as adversely affect other users of the airspace, since ATC may be required to reroute or delay other users in order to protect the failure aircraft. However, it is not intended that the requirement to "land as soon as practicable" be construed to mean "as soon as possible" the pilot retains his prerogative of exercising his best judgment and is not required to land at an unauthorized airport, at an airport unsuitable for the type of aircraft flown or to land only minutes short of his destination. C. IFR conditions. If the failure occurs in IFR conditions, or if paragraph 2 of this section can't be complied with, each pilot shall continue the flight according to the following: • Route: 1) By the route assigned in the last ATC clearance received; 2) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance; 3) In the absence of an assigned route, by the route that A TC has advised may be expected 199
in a further clearance; or 4) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance by the route tiled in the night plan. • Altitude. At the IDGHEST of the following altitudes or Flight Levels FOR THE ROUTE SEGMENT BEING FLOWN: 1) The altitude or flight level assigned in the last ATC clearance received; 2) The minimum altitude (converted, if appropriate, to minimum night level as prescribed in CCAR Part 91.121) for 1FR operations; or 3) The altitude or flight level ATC has advised may be expected in a further clearance. NOTE: The intent of the rule is that a pilot who has experienced two-way radio failure should select the appropriate altitude for the particular route segment being flown and make the necessary altitude adjustments for subsequent mute segments. If the pilot received an "expect further clearance" containing a higher altitude to expect at a specified time or fix, he/she should maintain the highest of the following altitudes until that time/fix: (1) His/her last assigned altitude, or (2) the minimum altitude/flight level for IFR operations. Upon reaching the time/fix specified, the pilot should commence his/her climb to the altitude he/s~e was advised to expect If the radio failure occurs after the time/fix specified, the altitude to be expected is not applicable and the pilot should maintain an altitude consistent with I or 2 above. If the pilot receives an "expect further clearance (EFC)", containing a lower altitude, the pilot should maintain the highest of Ior 2 above. Example 1 A pilot experiencing two-way radio failure at an assigned altitude of7 000 feet is cleared along a direct route which will require a climb to a minimum 1FR altitude of 9 000 feet, should climb to reach 9 000 feet at the time or place where it becomes necessary (see CCAR Part 91.177). Later while proceeding along an airway with an MEA of 5 000 feet, the pilot would descend to 7 000 feet (the last assigned altitude), because that altitude is higher than the MEA. Example2 A pilot experiencing two-way radio failure while being progressively descended to lower attitudes to begin an approach is assigned to 2 700 feet until crossing the VOR and then cleared for the approach. The MOCA along the airway is 2 700 feet and MEA is 4 000 feet. The aircraft is within 22NM of the VOR The pilot should remain at 2 700 feet until crossing the VOR because that at the altitude is the minimum IFR altitude for the route segment being flown Example3 The MEA between A and B -5 000 feet. The MEA between Band C - S 000 feet. The MEA between C and D - II 000 feet The MEA between D and E - 7 000 feet. A pilot had been cleared via A B, C, D, to E. While flying between A and B his assigned altitude was 6 000 feet and he was told to expect a clearance to 8 000 feet at B. Prior to receiving the higher altitude assignment, he experienced two-way failure. The pilot would maintain 6 000 to B, then climb to 8 000 feet (the altitude he was advised to expect) He would maintain 8 000 feet, then climb to 1I 000 at C, or prior 200
to C if necessary to comply with an MCA at C. (CCAR Part 91.177). Upon reaching D, the pilot would descend to 8 000 feet (even though the MEA was 7 000 feet), as 8 000 was the highest of the altitude situations stated in the rule (CCAR Part 91 .185). • Leave clearance limit: 1) When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect further clearance time if one has been received, or if one has not been received, as close as possible to the Estimated Time of Arrival (ETA) as calculated from the filed or amended (with ATC) Estimated Time en Route (ETE). 2) If the clearance limit is not a fix from which an approach begins, leave the clearance limit
at the expect further clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
NEAR MID-AIR COLLISION A near mid-air collision is defined as an occurrence in which the possibility of a collision existed as the result of two aircraft coming within 500 feet or less ofeach other. A high percentage of near mid-air collision occur below 8 000 feet AGL and within 30 miles of an airport. When operating VFR in these highly congested areas, whether you intend to land at an airport within the area or are just flying through, it is recommended that extra vigilance be maintained and that you monitor an appropriate control frequency. Normally the appropriate frequency is an approach control frequency. By such monitoring action you can "get the picture" of the traffic in your area When the approach controller has radar, radar traffic advisories may be given to VFR pilots upon request. .
MINIMUM FUEL ADVISORY A minimum fuel advisory is used by a pilot to inform ATC that the fuel supply has reached a state where the pilot can't accept any undue delay upon arrival at the destination. The minimum fhel advisory is not a declaration of an emergency, nor is it a request for priority. It does indicate that an emergency situation may develop if any undue delay occurs during the rest of the flight Pilot/Controller roles and responsibilities: A. Pilot: • Advise ATC of your minimum fuel status when your fuel supply has reached a state where, upon reaching destination, you can't accept any undue delay. • Be aware this is not an emergency situation, but merely an advisory that indicates an emergency situation is possible should any undue delay occur. • On initial contact the tern "minimum fuel", should be used after stating call sign.
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Example: SALT LAKE APPROACH, UNITED 621, "MINIMUM FUEL". • Be aware a minimum fuel advisory does not imply a need for traffic priority. • If the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, you should declare an emergency account low fuel and report fuel remaining in minutes (Reference-Pilot/Controller Glossary, Fuel Remaining). B. Controller: • When an aircraft declares a state of minimum fuel, relay this information to the facility to whom control jurisdiction is transferred. • Be alert for any occurrence that might delay the aircraft.
WIND INDICATORS Some airports have a number of wind indicators located around the perimeter of the field as well as a center field windsock. When there is a significant difference in speed or direction between the center field windsock and one or more of the boundary wind indicators, the tower can report that a w4td shear condition exists.
SAFETY ALERT A safety alert will be issued to pilots being controlled by ATC in either of two circumstances. A controller will issue a safety alert when, in the controller's opinion, the aircraft's altitude will put it in unsafe proximity to the surface or an obstacle. A controller will also issue an alert if he/she becomes aware of another aircraft, not controlled by him/her, that will put both aircraft in an unsafe proximity to each other. Pilot/Controller roles and responsibilities: A. Pilot: • Initiates appropriate action if a safety alert is received from ATC. • Be aware that this service is not always available and that many factors affect the ability of the controller to be aware of a situation in which unsafe proximity to terrain, obstructions, or another aircraft may be developing. B. Controller: • Issues a safety alert if he is aware an aircraft under his control is at an altitude which, in the controller's judgment, places the aircraft in unsafe proximity to terrain, obstructions or another aircraft. Types of safety alerts are: 1) Terrain or Obstruction Alert-Immediately issued to an aircraft under his control if he is aware the aircraft is at an altitude believed to place the aircraft in unsafe proximity to terrain or obstructions. 2) Aircraft Conflict Alert-Immediately issued to an aircraft under his control if he is aware of an aircraft not under his control at an altitude believed to place the aircraft in unsafe proximity to each other. With the alert, he offers the pilot an alternative, if 202
feasible. • Discontinues further alerts if informed by the pilot that he is taking action to correct the situation or that he has the other aircraft in sight.
WAKE TURBULENCE Every aircraft generates a wake while in flight Initially, when pilots encountered this wake in flight, the disturbance was attributed to ''prop Wash" It is known, however, that this disturbance is caused by a pair of counter rotating vortices trailing from the wing tips. The vortices from larger aircraft pose problems to encountering aircraft. For instance, the wake of these aircraft can impose toning moments exceeding the roll-control authority of the encountering aircraft. Further, turbulence generated within the vortices can damage aircraft components and equipment if encountered at close range. The pilot must learn to envision the location of the vortex wake generated by larger (transport category) aircraft and adjust the night path accordingly. During ground operations and during take-off, jet engine blast (thrust stream turbulence) can cause damage and upsets if encountered at close range. Exhaust velocity versus distance studies at various thrust levels have shown a need for light aircraft to maintain an adequate separation behind large turbojet aircraft. Pilots of larger aircraft should be particularly careful to consider the effects of their "jet blast'', on other aircraft, vehicles, and maintenance equipment during ground operations. Lift is generated by the creation of a pressure differential over the wing surface. The lowest pressure occurs over the upper wing surface and the highest pressures under the wing. This pressure differential triggers the rollup of the airflow aft of the wing resulting in swirling air masses trailing downstream of the wing tips. After the roll up is completed, the wake consists of two counter rotating cylindrical vortices. (See Figure 7-1 ). Most of the energy is within a few feet of the center of each vortex, but pilots should avoid a region within about 100 feet of the vortex core.
, Figure 7-1 Vortex Generation
Vortex Strength The strength of the vortex is governed by the weight, speed, and shape of the wing of the generating aircraft. The vortex characteristics of any given aircraft can also be changed by extension of naps or other wing configuring devices as well as by change in speed. However, as the basic factor is weight, the vortex strength increases proportionately. Peak vortex tangential speeds exceeding 300 feet per second have been recorded. The greatest vortex strength occurs when the 203
generating aircraft is HEAVY, CLEAN, and SLOW. In rare instances a wake encounter could cause in-night structural damage of catastrophic proportions. However, the usual hazard is associated with induced rolling moments which can exceed the roll-control authority of the encountering aircraft. In flight experiments, aircraft have been intentionally flown directly up trailing vortex cores of larger aircraft's was shown that the capability of an aircraft to counteract the roll imposed by the wake vortex primarily depends on the wingspan and counter-control responsiveness of the encountering aircraft. Counter control is usually effective and induced roil minimal in cases where the wingspan and ailerons of the encountering aircraft extend beyond the rotational now field of the vortex. It is more difficult for aircraft with short wingspan (relative to the generating aircraft) to counter the imposed roll induced by vortex now. Pilots of short span aircraft, even of the high performance type, must be especially alert to vortex encounters (See Figure 7-2 Wake Vortex Flow Field). The wake of larger aircraft requires Figure 7-2 Wake Vortex Flow Field the respect of all pilots. Vortex Behavior
Trailing vortices have certain behavioral characteristics which can help a pilot visualize the wake location and thereby take avoidance precaution. Vortices are generated from the moment aircraft leave the ground, since trailing vortices are a by-product of wing lift. Prior to take-off or touchdown pilots should note the rotation or touchdown point of the preceding aircraft (See Figure 7-3 Wake Begins/Ends).
~~:. ~tl Wake Ends
...
~/ ~ Wake Begins
Figure 7-3 Wake Begins/Ends
The vortex circulation is outward, upward and around the wing tips when viewed from either ahead or behind the aircraft. Tests with large aircraft have shown that the vortices remain spaced a bit less, than a wingspan apart, drifting with the wind, at altitudes greater than a wingspan from the ground. In view of this, if persistent vortex turbulence is encountered, a slight change of altitude and lateral position (preferably upwind) will provide a night path clear of the turbulence. Flight tests have shown that the vortices from larger (transport category) aircraft sink at a rate of several hundred feet per minute, slowing their descent and diminishing in strength with time and
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distance behind the generating aircraft. Atmospheric turbulence hastens breakup. Pilots shodd fly at or above the preceding aircraft's night path, altering course as necessary to avoid the area behind and below the generating aircraft (see Figure7-4). However vertical separation of 1 000 feet may be consider safe.
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Figure 7-4 Vortex Flow Field
When the vortices of larger aircraft sink close to the ground (within- I 00 to 200 feet), they tend to move laterally over the ground al airspeed of2 or 3 knots (see Figure 7-5).
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Figure 7-5 Vortex Sink Rate
A crosswind will decrease the lateral movement of the upwind vortex and increase the movement of the downwind vortex. Thus a light wind with across runway component of 1 to 5 knots could result in the upwind vortex remaining in the touch-down zone for a period of time and hasten the drift of the downwind vortex to ward another runway (see Figure 7-6). Similarly, a tail wind condition can move the vortices of the preceding aircraft forward into the touchdown zone. THE LIGHT QUAR1ERING TAIL WIND REQUIRES MAXIMUM CAUTION. Pilots should be alert to large aircraft upwind from their approach and take-off flight paths (see Figure 7-7).
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Figure 7-6 Vortex Movement in Ground
Figure 7-7 Vortex Movement in Ground Effect (Wind)
Effect (No Wind)
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Operations Problem Areas A wake encounter can be catastrophic. In 1972 at Fort Worth a DC-9 got too close to DC-10 (two miles back), rolled, caught a wingtip, cartwheel coming to rest in an inverted position on the runway. All aboard were killed. Serious and even fatal GA accidents induced by wake vortices are not uncommon. However, a wake encounter is not necessarily hazardous. It can be one or more jolts with varying severity depending upon the direction of the encounter, weight of the generating aircraft, size of the encountering aircraft, distance from the generating aircraft, and point of vortex encounter. The probability of induced roll increases when the encountering aircraft's heading is generally aligned with the flight path of the generating aircraft. AVOID THE AREA BELOW AND BEHIND THE GENERATING AIRCRAfT, ESPECIALLY AT LOW ALTITUDE WHERE EVEN A MOMENTARY WAKE ENCOUNTER COULD BE HAZARDOUS. This is not easy to do. Some accidents have occurred even though the pilot of the trailing aircraft had carefully noted that the aircraft in front was at a considerably lower altitude. Unfortunately, this does not ensure that the night path of the lead aircraft will be below that of the trailing aircraft. Pilots should be particularly alert in calm wind conditions and situations where the vortices could: A. Remain in the touchdown area. B. Drift from aircraft operating on a nearby runway. C. Sink into the take-off or landing path from a crossing runway. D. Sink into the traffic pattern from other airport operations. E. Sink into the night path of VFR aircraft operating on the hemispheric altitude 500 feet below. Pilots of all aircraft should visualize the location of the vortex trail behind larger aircraft and use proper vortex avoidance procedures to achieve safe operation. It is equally important that pilots oflarger aircraft plan or adjust their night paths to minimize vortex exposure to other aircraft.
Vortex Avoidance Procedures Under certain conditions, airport traffic controllers apply procedures for separating IFR aircraft. The controllers will also provide to VFR aircraft, with whom they are in communication and which in the tower's opinion may be adversely affected by wake turbulence from a larger aircraft, the position, altitude and direction of Iright of larger aircraft followed by the phrase "CAUTION-WAKE TIJRBULENC". WHE1HER OR NOT A WARNING HAS BEEN GIVEN, HOWEVER,'llffi PILOT IS EXPECTED TO ADJUST IDS OR HER OPERAIIONS AND FLIGHT PATH AS NECESSARY TO PRECLUDE SERlOUS WAKE ENCOUNTERS. The following vortex avoidance procedures are recommended for the various situations: A. Landing behind a larger aircraft-same runway: Stay at or above the larger aircraft's final approach night path-note its touchdown point- land beyond it. B. Landing behind a larger aircraft-when parallel runway is closer than 2 500 feet: Consider possible drift to your runway. Stay at or above the larger aircraft's final approach Iright
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path-note its touchdown point C. Landing behind a larger aircraft-crossing runway: Cross above the larger aircraft's night path. D. Landing behind a departing larger aircraft-same runway: Note the larger aircraft's rotation point-land well prior to rotation point. E. Landing behind a departing larger aircraft-crossing runway: Note the larger aircraft's rotation point-if past the intersection -
continue the approach-land prior to the
intersection. If larger aircraft rotates prior to the intersection, avoid night below the larger aircraft's night path. Abandon the approach unless a landing is ensured well before reaching the intersection. F. Departing behind a larger aircraft: Note the larger aircraft's rotation point-rotate prior to larger aircraft's rotation point-continue climb above the larger aircraft's climb path until . turning clear of his wake. A void subsequent headings which will cross below and behind a larger aircraft. Be alert for any critical take-off situation which could lead to a vortex encounter. G. Intersection take-offs -same runway: Be alert to adjacent larger aircraft operations, particularly upwind of your runway. If intersection take-off clearance is received, avoid subsequent heading which will cross below a larger aircraft's path. H. Departing or landing after a larger aircraft executing a low approach, missed approach or touch-and-go landing: Because vortices settle and move laterally near the ground, the vortex hazard may exist along the runway and in your night path after a larger aircraft has executed a low approach, missed approach or a touch-and-go landing, particular in light quartering wind conditions. You should ensure that an interval of at least 2 minutes has e 1apsed before your take-off or landing.
I. En route VFR (thousand-foot altitude plus 500 feet): A void night below and behind a large aircraft's path. If a larger aircraft is observed above on the same track (meeting or overtaking) adjust your position laterally, preferably upwind.
Helicopters In a slow hover taxi or stationary hover near the surface, helicopter main rotor(s) generate downwash producing high velocity outwash vortices to a distance approximately three times the diameter of the rotor. When rotor downwash hits the surface, the resulting outwash vortices have behavioral characteristics similar to wing tip vortices produced by fixed wing aircraft. However, the vortex circulation is outward, upward, around, and away from the main rotor(s) in all directions. Pilots of small aircraft should avoid operating within three rotor diameters of any helicopter in a slow hover taxi or stationary hover. In forward night, departing or landing helicopters produce a pair of strong, high-speed trailing vortices similar to wing tip vortices of larger fixed wing aircraft. Pilots of small aircraft should use caution when operating behind or crossing behind landing and departing helicopters.
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Pilot Responsibility Government and industry groups are making concerted efforts to minimiu or eliminate the hazards of trailing vortices. However, the flight disciplines necessary to ensure vortex avoidance during VFR operations must be exercised by the pilot Vortex visualization and avoidance procedures should be exercised by the pilot using the same degree of concern as in collision avoidance. Wake turbulence may be encountered by aircraft in night as well as when operating on the airport movement area (Reference - Pilot/Controller Glossary, Wake Turbulence). Pilots are reminded that in operations conducted behind all aircraft, acceptance of instructions from ATC in the following situations is an acknowledgment that the pilot will ensure safe take-off and landing intervals and accepts the responsibility of providing his own wake turbulence separation. A. Traffic information, B. Instructions to follow an aircraft, and C. The acceptance of a visual approach clearance. For operations conducted behind heavy aircraft ATC will specify the word ''heavy" when this information is known. Pilots of heavy aircraft should always use the word "heavy" in radio communications. Air Traffic Wake Turbulence Separations Because of the possible effects of wake turbulence, controllers are required to apply no less than specified minimum separation for aircraft operation behind a heavy jet and, in certain instances, behind large non-heavy aircraft. A. Separation is applied to aircraft operating directly behind a heavy jet at the same altitude or less than 1 000 feet below: • Heavy jet behind heavy jet- 4 miles. • Smal1/large aircraft behind heavy jet- 5 miles. B. Also, separation, measured at the time preceding aircraft is over the landing threshold, is provided to small aircraft: • Small aircraft landing behind heavy jet- 6 miles. • Small aircraft landing behind large aircraft- 4 miles. C. Additionally, appropriate time or distance intervals are provided to departing aircraft. Two minutes or the appropriate 4 or 5 miles radar separation when take-off behind a heavy jet will be: • from the same threshold; • on a crossing runway and projected night paths will cross; • from the threshold of a parallel runway when staggered ahead of that of the adjacent runway by less than 500 feet and when the runways are separated by less than 2 500 feet NOTE: Pilots, after considering possible wake-turbulence effects, may specifically request waiver of the 2-minutes interval by stating, "request waiver of 2-minute interval" or a similar 208
statement Controllers may acknowledge the statement as pilot acceptance of responsibility for wake turbulence separation and, if traffic pennlts, issue take-off clearance. A 3-minute interval will be provided when a small aircraft will take-off: A. From an intersection on the same runway (same or opposite direction) behind a departing large aircraft; B. In the opposite direction on the same runway behind a large aircraft take-off or low/missed approach. NOTE: This 3-minutes interval may be waived upon specific pilot request A 3-minutes interval will be provided for all aircraft taking off when the operation are as described A and B above, the preceding aircraft is a heavy jet, and the operations are on either the same runway or parallel runway separated by less than 2 500 feet Controllers may not reduce or waive this interval. Pilots may request additional separation i.e., 2 minutes instead of 4 or 5 miles for wake turbulence avoidance. This request should be made as soon as practical on ground control and at least before taxiing onto the runway. Controllers may anticipate separation and need not withhold a take-off clearance for an aircraft departing behind a large/heavy aircraft if there is reasonable assurance the required separation will exist when the departing aircraft starts take-off roll.
SECTION 8
FLIGHT PHYSIOLOGY
Many fight accidents show that pilots are the most important element in the aircraft's systems. How well pilots' body and mind work have a direct influence on flight operation, and then influencing on flight safety. As a pilot, we must understand the characteristic of our body functions and our mind, know how they react to the various environment situations encountered during flight In order to take measures actively to prevent and overcome corresponding disadvantageous, which may affect flight safety. What we learn in this chapter can help we deal with the limitations of both our body and the environment in which we operate. At first, we will discuss how our vision work in bright sunlight and at night It also covers some of the common visual illusions and how we can deal with them. Then we will discuss spatial disorientation and some of the confusing sensory inputs encountered in flight, study the effects of flying in reduced atmospheric pressure and what happens when your normal respiration is changed. At last, we will discuss how alcohol and drugs affect human performance.
INTRODUCTION OF VISION IN FLIGHT Vision is the most important sense that we have and nearly everything that we perceive is
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visual or heavily supplement by it In collision avoidance and depth perception, especially in the visual flight, the vision sense is by far most important When we perceive the outside world through our vision system, the visual illusions and blind spot are inevitable for the limitations of our mind information processing and vision sensor's structure. The more we know the vision system and how it functions, the easier it will be to compensate for these illusions and blind spot Structure and Function of the Eye
The cornea is a transparent film through which light first enters the eye. It can be thought as a "windshield" which protects the rest of the eye from the outside world. The cornea is supported and held in shape by a perfectly transparent fluid called aqueous humour. The iris is the colored part of the eye which changes its shape in response to the intensity of the light, causing the pupil - the black aperture which forms at the centre of the iris, to become larger or smaller thereby admitting more or less of the light through to the lens. The ciliary muscles alter the shape of the flexible lens allowing it to focus objects at various distances onto the retina. The retina has special receptor cells which convert light energy into nerve impulses. The interior surface of the retina is covered with many millions of light-sensitive cells called cones and rods.
Figure 7-8 The Anatomy of tbe Eye
The cones are centrally located around the center of the retina They gradually diminish in number as the distance from the center increases. The cones specialize in color perception and fine detail. Directly behind the lens on the retina is a small, notched area called the fovea, which is the most sensitive area on the retina which contains a large number of cone receptors. When we look directly at an object, the image is focused mainly on it. however, The cones require bright light they function poorly in dim light. That is why we can't see color as vividly at night as we can in the day. The rods are located in the periphery of the retina, arranged concentrically around the cones. The rods are our dim light and night receptors and can "see" only in black and white, but it is about 210
10 000 times more sensitive to light than the cones, which make it best in low light and are chiefly :-esponsible for night vision. Since the cones do not see well in the dark, so we may not be able to see an object if the image is focused mainly on the fovea This is so-called night blind spot Using the rods in low light intensity by look slightly to one side of objects, for example, 5 to 10 off center of the subject, rather than directly at them, can help us compensate for the night blind spot in the center of our vision. In the eye, there is a spot known as the blind spot at which nothing can be seen. The blind spot is the place in the retina at which the optic nerve enter the eye. At this point there are neither rods nor cones, and so no vision is possible. This can be demonstrated by the following experiment. Covering the left eye, hold the book at ann's length and using the right eye to look at the right aircraft in Figure 7-9. Move the book slowly closer to the face while fixing your gaze on the right aircraft, the right aircraft will disappear from your vision when its image falls on the blind spot. In general, the blind spot will be overcome when both eyes are used, but if pilot's visual field is blocked partly, or one of his eyes does not work well, this phenomena may take place.
,--...__ 1
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•
-"'4"•,4'»
................
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Figure 7-9 Blind Spot
Night Vision Night vision is derived from the rods in the retina. The cones in our eyes adapt quite rapidly to changes in light intensities, but the rods do not. This is the problem of dark adaptation. Dark adaptation is the process by which the eyes adapt for optimal night visual acuity under conditions of low ambient illumination. The eyes require between 30 and 45 minutes to fully adapt to minimal lighting conditions. The lower the starting level of illumination, the more rapidly complete dark adaptation is achieved. There are some ways we can do to minimize the time necessary to achieve complete dark adaptation and to avoid losing it A. avoid exposure to bright lights before and during the flight; B. use sunglasses if you will be flying from daylight into an area of increasing darkness; C. keep the instrument panel and interior lights turned up no higher than necessary. 211
Furthermore, our diet and general physical health have an impact on how well we can see in the dark. Deficiencies in vitamins A and C have been shown to reduce night acuity. Other factors, such as carbon monoxide poisoning, smoking, alcohol, certain drugs, and a lake of oxygen also can greatly decrease our night vision.
Empty Field Myopia and Night Myopia Empty field myopia, also called the empty visual field effect, this may occur when looking out of the cockpit at a featureless sky and that is devoid of objects, contrasting colors, or patterns. Because there is nothing for the eye to focus between the cockpit and infinity, the lens takes up its rest position for ciliary muscle relaxed, producing a focal distance between one and two meters from the eye. This is aggravated by the windscreen frame and other parts of the aircraft structure which attract the focusing point in from infinity. As a result the eyes appear to search the surrounding area, but in fact, it is focused at a very close distance. If an aircraft enters the pilot's field of vision, it may not be seen. Focusing on ground objects at frequent intervals, or in low visibility to focus on the wing tips from time to time, empty field myopia can be alleviated to some extent Night myopia, is also called night-induced nearsightedness. It is similar to empty field myopia, but is more pronounced because the visual references at night are more scarce that those of in daytime. At night, there is nothing to observe out of the aircraft, our eyes automatically focus on a point one to two meters in front of us. Searching out and focusing on distant light sources, no matter how dim, will help prevent the onset of it
Scanning Techniques Scanning the sky for other aircraft is important in avoiding mid-air collisions, particularly when flying under visual flight rules. In a airspace which flight conflict may be happened, we may can not see the aircraft, not to say avoiding the potential mid-air collisions because our vision system has some limitations, our mind information processing and specific operation, and flight path change, all need time. Some investigations show that less than 10% of mid-air collisions occur between air craft approaching head-on. Therefore, it is essential to develop and practice a scanning technique that allows the efficient monitoring of the surrounding air space as well as the cockpit instrumentation. When developing a technique for effective visual scanning in day light, it is necessary to perform a series of short, regularly spaced eye movements which bring successive areas of sky into the fovea. Scan from right to left or left to right, beginning a scan at the top of the visual field in front of you and then moving the eyes inward towards the bottom. Each movement should be 10° at most, and each area should be observed for at least I second but not longer than 2 ~ 3 seconds. The alternating movement and stopping of the eyes during the scan is known as the saccade/rest cycle. Unlike day scanning however, off-center viewing is used to focus objects on the rods rather than the fovea blind spot in night or in low visibility, moving our eyes slowly and in small sectors, 212
using off-center viewing and avoid staring in one place for too long. Avoid looking directly at an object for more than 2- 3 seconds because the retina will become accustomed to the light intensity and the image begin to fade. To keep it clearly visible, new areas in the retina must be exposed to the image. Small, circular eye movements help eliminate the fading. We also need to move our eyes more slowly from sector to sector than during the day to prevent blurring. So, we should use the off-centre viewing that consists of search movements of the eyes, 10° above, below, or to either side, to locate an object, and small eye movements to keep the object in sight. Switching the eyes from one offset point to another every 2 - 3 seconds will enable the object to be detected in the peripheral field of vision. Maintaining a constantly updated situational awareness of what is going on in the sky around us, is the best chance of avoiding mid-air collision. Knowing where to look during the various phases of flight wilJ considerably improve lookout. This particularly applies when entering an aerodrome traffic zone or flying close to ground based navigation aids where one expects a greater concentration of traffic. In addition, the information available from radio calls made by other aircraft should be intelligently used to assess when extra vigilance is required and which areas of the sky to search. An effective scan pattern is necessary to ensure that a pilot will see other aircraft in time to avoid potential mid-air collisions. Studies show that the time a pilot spends on visual tasks inside the cabin should represent no more than 1/4 to 113 of the scan time outside, or no more than 4 to 5 seconds on the instrureent panel for every 16 seconds outside. This means pilots should spend the majority of scan time outside the airplane, and outside scanning is necessary when in radar contact in VFR conditions, that is to say, 2/3 to 3/4 of a pilot's time should be spent scanning outside the aircraft, the best method for effective collision avoidance would be to look outside for about 15 seconds, and then inside for about 5 seconds, then repeat. It is much easier to see an aircraft which is moving relative to the observer. Unfortunately, aircraft which present a collision hazard are usually on the horizon with little or no apparent horizontal or vertical movement. The image only grows larger as the threat aircraft gets closer. So, there are something we must understand, and special vigilance must be exercised in these situations. An airplane which is ahead of you and moving from Left to right, or from right to left, should pass in front of you. An aircraft that appears to have no relative motion and stays in one scan quadrant is likely to be on a collision bourse. If a target shows no lateral or vertical motion, but increases in size, we must take evasive action.
SPATIAL DISORIENTATION We live and work in a one-G environment Standing on the ground, our orientation is not difficult with surroundings. However, flying is in three-dimensional realm, when we enter it, some conflict between our see and feel may turn up, even produce some illusions. Everyone is subject to spatial disorientation; even experienced pilots have felt its effects in one form or another and in varying degrees. Some situations are more disorienting than others. Understanding how they are 213
created and what illusions are produced is to help to us to deal effectively with these unrealistic sensations. Three Main Senses
A pilot awareness of his body's position is a result of input from three main senses: vision, vestibular, and kinesthetic. That is to say, we get information, which is used to determine orientation, from the body's sense organs- the eyes, the hearing and vestibular organs of the inner ear, the kinesthetic of nerve endings in the skin, muscles and joints and pass to the brain. VISual Sense As we have discussed in Section A, vision helps us maintain balance and our position relative to objects around us. When other sensory input is contradictory or confusing, the brain relies primarily upon sight to determine orientation. In darkness or limited visibility, when few out-side visual references are available, pilots need to rely heavily on their visual sense to interpret the flight instruments for accurate information. Vestibular Sense The vestibular organs are composed of the semicircular canals and static organ, which are located-in our inner ear. They are easily deceived by slow or gradual movement Our vestibular sense is primarily due to this sense tells pilot when he are turning, climbing, descending, speeding up, or slowing down. It also senses gravity and G-loads created by centrifugal force. The semicircular canals sense angular acceleration such as roll, pitch, and yaw. The three semicircular canals are filled with fluid and are located so that each canal lies along a specific axis. At the base of each canal are small hair cells that detect movement when they are displaced. When you maneuver the airplane or move your head, the semicircular canals move too, while the fluid remains temporarily stationary. This deflects tile sensory hairs and sends a nerve impulse to the brain, which interprets the "movement" as motion around an axis. The semicircular canals may not be able to sense a slow rate of rotation. They also are unable to sense movement after prolonged periods of uniform movement. The static organ is responsible for the perception of linear acceleration, which is movement forward and back, side to side, and up and down. One of the major problems with this sensory organ is its inability to tell the difference between gravity caused by the earth and G-loads caused by centrifugal force. J(jnesthetic Sense When your awareness of position is obtained from the nerves in your skin, joints and muscles, it is called the kinesthetic sense. Using this sense is sometimes called ''flying by the seat of your pants", and this is literally what you are doing. Kinesthetic sense is unreliable, however, because the brain can't tell the difference between input caused by gravity and that of maneuvering G-loads. Visual Illusion and Vestibular Illusion An illusion can be defined as a false impression or unreal vision formed when sensory
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information is misinterpreted by the brain. Spatial disorientation is also called disorientation or flight illusion. it is a false perception of orientation of the aircraft, with respect to spatial references such as flight path and altitude, or reference to objects with respect to expected shape or size. These may occur when the sensory organs send conflicting information to the brain. In the absence of powerful visual information. complex and interactive forces can create specific illusions. In the absence of external visual reference, e.g. flying in cloud, conditions of poor visibility or at night, the co~cting sensory information can be overcome by reference to the flight instruments. All pilots who fly 1n instrument conditions or at night may be subject to spatial disorientation, understanding the various types and how they occur, and taking preventative measures when appropriate, rely on the indications of the flight instruments, are help to overcome its passive effects. The best method to prevent or overcome spatial disorientation is to rely entirely on the indications of the flight inst11Jments. There are two kinds of spatial disorientation: visual illusion and vestibular illusion.
Visual Illusions There are many different types of visual illusions that we can experience during flight, such as auto-kinesis, false horizon. oculogravic illusion. and some other landing illusions. They commonly occur in pilots of all levels of skill and experience. Impulses from the sensory organs of the eye, are conducted along the optic nerve to the brain for interpretation. The eye is very reliable for orientation as long as adequate reference points are available. However, in flight, objects seen from the air often look quite different from when seen on the ground thus causing difficulty in interpreting visual cues. The problems are compounded
in conditions of poor visibility and visual illusions can lead to spatial disorientation or to landing errors. 1) Auto-kinesis. In the dark, when we stared at a stationary light for several seconds, the light will appear to move about. The apparent movement will increase if the light source is allowed to become the prime focus of attention. This visual illusion is caused by staring at a single point of light against a dark background, such as a ground light or bright star, for more than a few seconds. After a few moments, the light will appear to move on its own. If pilot attempt to align the aircraft in sole relation to the light, he may lose control of the airplane. To avoid the effects of this visual illusion, when flying at night it is important to shift the gaze so as not to stare at a single light source.
2) False Horizons. In the absence of a clearly defined horizon. the pilot may mistakenly choose another line as a reference and, for example, may fly parallel to a sloping cloud bank instead of the earth's surface. We called it false horizon. False horizon is another kind of visual illusion, which occurs when the natural horizon is obscured or not readily apparent It can be generated by confusing bright stars and city lights. It may occur when we are flying toward the shore of an ocean or a large lake, for the relative darkness of the water, the lights along the shoreline may be mistaken for the stars in the sky.
3) Oculogravic IDusions. The oculogravic illusion can be considered as the visual component 215
of the somatogravic illusion that we will discuss subsequently. When an aircraft accelerates and there is a backward rotation of the resultant force vector, the pi lot may experience an illusion of pitch up. This may be accompanied by an apparent upward movement and displacement of objects, such as a line of lights, within the visual field. 4) Landiug IDusions. Landing illusions occur in many forms. Elements that cause any type of visual obscuration such as rain, haze, or a dark runway environment can cause low-than normal approaches. Bright runway light, steep surrounding terrain, and a wide runway can produce the illusion of being too low, and there is the tendency to fly a higher-than normal approach. There are a variety of atmospheric and terrain conditions can produce landing illusions (Figure 7-1 0). When we encounter these situations, we must be: able to recognize them and use all the resources available to counteract them. LANDING Situation
ILLUSIONS illusion
Result
Ups! oping Runway or Terrain
Greater Height
Lower Approaches
Downsloping Runway or Terrain
Less Height
Higher Approaches
Narrower-Than-Usual Rtmway
Greater Height
Lower Approaches
Bright Runway and Approach Lights
Less Distance
Higher Approaches
Wider-Than-Usual Runway
Less Height
Higher Approaches
Featureless Terrain
Greater Height
Lower Approaches
Rain on Wmdscreen
Greater Height
Lower Approaches
Haze
Greater Height
Lower Approaches
Penetration of Fog
Pitching Up
Steeper Approaches
Figure 7-10 Atmospheric and Terra.i n Conditions Can Produce Visual Wusions
5) Runway and Terrain Slope musion. An upsloping runway or terrain, or both, can create the illusion that the aircraft is at a higher altitude than it actually is. This can lead to a lower than normal approach being flown. The runway or approach terrain which slopes down can have the opposite effect. It's common that airports have run':"ays with a slope, some of them having three percent or more, which may give you a strong landing illusion. If you know why and how it is happened, you will be able to identify them long before they become problems. Read the aeronautical chart and Airport/Facility Directory for your destination airport, take advantage of a visual approach slope indicator system to verify your approach height and descent rate, look for other clues, such as steep or featureless surrounding terrain, all contribute to eliminate these illusions (Figure 7-11).
6) Runway Width musion. When approaching a runway that is narrower than usual, the illusion may appear that the aircraft is higher than it actually is. This illusion may lead a pilot 216
descends too low on approach. This can lead to a low approach being flown (Figure 7-12). Conversely runways significantly wider than those normally used will give a pilot the impression of being too low on glide slope, may result in higher than desired approaches
c Figure 7-11 IUusion Created during Approach Caused by Sloping Runway
Normal approach
Figure 7-11 Dlusion Created during Approach Caused by Change in Runway Width (Broken Line Runway Is Normal)
7) Featureless Terrain Dlusion. An absence of visible ground feature, such as when landing
over water, darkened areas or terrain made featureless by snow, can create the illusion that the aircraft is at a higher altitude than is the case, which may lead a pilot descends too low on approach. "Black hole" Effect and "White hole" Effect are two types of it. When landing at night at an aerodrome with no surrounding lights, pilots face what bas become known as the "black hole". There is nothing to provide the dimension of scale leading to false perception of distance and 217
angle if the runway edge lights are the only visible cue, which may lead to an excessively low approach being flown with the risk of undershooting the runway. When landing at an runway ,which surrounding is covered by snow, no other reference objects to use, pilots feel that it is difficult to find the runway, or the aircraft is at a high altitude than is the case. This is called "black bole" Effect. The first one is called ''Black bole" Effect, and the second one is called "White hole" Effect. 8) Atmospheric Dlusions. Atmospheric haze, mist or fog, or rain on the windscreen, may lead to refraction of light. Haze may make pilot think that the aircraft is farther from the runway than it actually is. Rain on the windscreen can create an illusion of being at a higher altitude than you are. When penetrating mist or fog , an illusion of pitching up can occur leading to the approach being steepened abruptly. 9) Ground Lighting Dlusion. It refers to lights on a straight path such as a road, and even lights on moving vehicles, and that can be mistaken for runway or approach lights. Bright runway and approach landing systems, especially where few lights illuminate the surrounding terrain, may create the illusion of there being less distance to the runway threshold. Flying over terrain which has few lights to provide height cues may lead to a lower than normal approach being flown. Vestibular Illusions In general, we get our orientation primarily through our vision, but we can not ignore the role of the vestibular and kinesthetic senses. In fact, when we work at night or in marginal weather conditions, seat on an unstable moving platform at altitude with our vision cut off from the earth, horizon or other fixed reference, the visual cues are fewer, they provide much information for our orientation. However, these senses are not reliable, they can give false cues about our orientation. Especially in flying, we are susceptible to misinterpreting certain body sensations caused by aircraft's angular acceleration. The probability of spatial disorientation occurring is quite high if our orientation is depended on them. These illusions are called vestibular illusion. These illusions are most common at night and during the time of restricted visibility. Relying on the instruments and believing what they tell you, regardless of"how it feels", are the keys to avoid vestibular illusion. 1) Coriolis Dlusion. An abrupt head movement while making a prolonged constant rate turn, can produce a strong sensation of rotation or movement in an entirely different axis. The phenomenon is known as Coriolis Illusion. Coriolis illusion is considered to be one of the most deadly. It is an illusion of turning in a different axis, which is produced by the cross~oupled response arising from the stimulation of the semi-circular canals by the interaction of angular motion in different planes. In a prolonged, constant-rate turn, if a pilot tilt his bead down to change a fuel tank or pick up a pencil, the rapid head movement puts the fluid in motion in more than one semicircular canal. This creates an overwhelming sensation of rotating, turning, or accelerating along an entirely different plane. An attempt to stop the sensation by maneuvering the airplane may put it into a dangerous attitude. Not moving your head too fast in limited visibility or darkness is the best way to avoid it. 218
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2) Leans. This is one of the most common types of spatial disorientation also called illusion of level flight. This illusion often occurs when an abrupt recovery or a rapid correction is made, that is to say, an abrupt correction of a banked angle can create the illusion of banking in the opposite direction. In straight and level flight the fluid in the semicircular canals of the ear is stationary and the hair detectors are not deflected. Any movement of the head, for example result of aircraft roll or pitch, will cause a reaction in the appropriate pair of canals and this is perceived as movement in the appropriate direction. The signal to the brain is the result of the sensory hairs being deflected by the relative movement of the fluid, but continuing the motion at a steady rate will allow the fluid to catch up with the aircraft and the hairs will revert to their original upright position, which leads to a false perception that the aircraft is once again flying straight and level. So, when a aircraft is in an abrupt recovery or a rapid correction, if the pilot makes such a recovery, his semicircular canals sense a roll in the opposite direction. This may cause he to reenter the original attitude. When be return the aircraft to a Wing-level condition, he wiJJ tend to lean in the direction of the incorrect bank until the semicircular canal fluids return to normal. From the information mentioned above, we can know that if we are in this state for some reasons, maintaining a level attitude for a minute or two generally, this illusion will be stopped. 3) Somatogravic IDusion. A rapid acceleration or deceleration can cause a somatogravic illusion. An acceleration can produce the illusion that you are in a nose-high attitude, even though you are still in straight-and-level flight. This may prompt you to lower the nose and enter a dive. A deceleration, such as rapidly retarding the throttle, produces the opposite effect. You may think you are in a dive and raise the nose. If you raise the nose too far, a stall may be produced. 4) Inversion IDusion. An abrupt change from a climb to straight and level flight can create the illusion of tumbling backwards. The effect may cause you to lower the nose abruptly, which may intensify the illusion.
HYPOXIA Our respiration relates to the construction of the atmosphere closely. The atmosphere is a mixture of gasses, oxygen possess about 21%, while 78% is nitrogen and 1% is other gasses, such as carbon dioxide and argon. Although the percentage of nitrogen, carbon dioxide and oxygen in the atmosphere remains constant with changes in altitude, the pressure or density of the air is less. It is well know that the tissues in our body can receive enough oxygen, but for some reasons, our normal respiration cycle may be interrupted or broken down, the body may can not get enough oxygen. In this condition, pilot's judgment may be impaired and flight skills may be cut down. Eventually, there is loss of consciousness and ultimately death. The symptoms are insidious at first and develop slowly, but progressive and more marked at altitudes above 10 000 ft. In all cases night vision is impaired from approximately 5 000 ft upwards. Hypoxia occurs when our brain and other tissues can not receive enough oxygen for some reasons. The mixture of air you breathe remains relatively uniform as attitude increases, but the pressure or density of the air is less. That is to say, there is less oxygen reaching the cells in our 219
body as plane climb. hypoxic hypoxia and anemic hypoxia are two typical types of hypoxia in flying.
Hypoxic Hypoxia Hypoxic hypoxia occurs when there is a lack of available oxygen in the atmosphere. It is considered to be the most lethal factor of all physiological causes of accidents. It can occur very suddenly at high altitudes during rapid decompression, such as loss of cabin pressure. It can also occur slowly at lower altitudes when we are exposed to insufficient oxygen over an extended period of time. The symptoms of hypoxia vary with the individual. Some of the common symptoms include: A. Anincrease in breathing rate; B. Lightheaded or dizzy sensation; C. Headache; D. Sweating; E. Tmgling or warm sensation;
F. Blue fingernails and lips; G Reduced visual field; H. Sleepiness or frequent yawning; I. Impaired judgment; J. Aslowing of decision-making processes; K. Afeeling of euphoria; L. Changes in personality traits.
Anemic Hypoxia When our blood is not able to carry a sufficient amount of oxygen to the cells in your body, a condition called anemic hypoxia occurs. Its symptoms are very similar to hypoxic hypoxia and can produce the loss of muscle power, a headache, and dizziness. If the poisoning is severe enough, it can result in death. This type of hypoxia is a result of a deficiency in the blood (anemia), rather than a lack of inhaled oxygen. Anemia can occur as a result of excessive bleeding, a stomach ulcer, or a diet deficiency. It also can occur when oxygen is not able to attach itself to hemoglobin. For pilots, the most common cases of anemic hypoxia come from carbon monoxide poisoning. Carbon monoxide (CO) is produced by incomplete combustion of carbonaceous material and is also presented in the exhaust fumes of piston engines and tobacco smoking. Hemoglobin has an affinity for carbon monoxide 200 times greater than its affinity for oxygen, it prevents oxygen from attaching to the hemoglobin and can produce anemic hypoxia. The symptoms are progressive starting with headache, nausea, dizziness and a reduction in vision. Continuing inhalation of carbon monoxide eventually leads to vomiting, loss of muscular power, unconsciousness and death. Susceptibility to carbon monoxide poisoning increases as altitude increases because of the reduction in oxygen partial pressure. Tobacco smoking also increases susceptibility, which causes a 220
mild case of CO poisoning. The effects of cigarette smoke are especially apparent by a reduction in visual acuity during a night flight. Smoking three cigarettes during a night flight can dramatically reduce the sharpness of your vision. Carbon monoxide poisoning can result from a faulty aircraft heater. If you suspect carbon monoxide poisoning, you should tum off the heater immediately, open the fresh air vents or windows, and use supplemental oxygen if it is available.
The Time of Useful Consciousness (fUC) The time of useful consciousness (IUC) is the maximum time that pilot bas to make a rational, lifesav.ing decision and carry it out following a lack of oxygen at a given altitude. Some people say that life expectancy at high altitudes without oxygen is a mailer of minutes, and the time of useful consciousness is even less. If pilot goes beyond this time, he may not be able to place an oxygen mask over his face, even if he tries. The time of useful consciousness is affected by many factors, such as flight altitude, climbing rate, pilot's activity level, pilot's health, and whether the pilot smoking or not (Fignre7-13). THE TIME OF USEFUL CONSCIOUSNESS Altitude
While sitting quietly
During moderate activity
40000 ft
12200m
30s
18 s
35 000 ft
10670m
45 s
30s
30 OOOFt
9140m
1 min and 15 s
45 s
25 000 ft
7620m
3 min
2min
22 OOOft
6710m
!Omin
Smin
20000 ft
6100m
12min
5min
18 000 ft
5490m
30min
20min
Figure 7-13 The Altitude and the Amount of Exertion Can Affect the Time of Useful Consciousness
Supplemental Oxygen Recovery from hypoxia usually occurs rapidly after a person bas been given oxygen. If someone has suffered severe hypoxia, his mental and physical performance may be reduced for several hours. There are something we should pay attention to, although it is possible to learn the early symptoms of hypoxia It is not to say, we can take corrective action certainly whenever they occur. An early symptom is impaired judgment. When the onset of hypoxia is rapid, our judgment may be impaired before you have a chance to recognize other symptoms. So, to avoid the effects of hypoxia, prevention is the best way. For civil aviation pilots, using supplemental oxygen may be the most effective way to prevent hypoxia. Federal regulations specify when pilot must use supplemental oxygen. As a general rule, when we fly above 10 000 feet (3 050 meters) during the day or above 5 000 feet (1 525 meters) at night, we should use supplemental oxygen. 221
Hyperventilation Hyperventilation is caused by a reduction of carbon dioxide in the blood, usually due to rapid breathing in a stressful situation. It is the term used to describe a breathing rate that is too rapid and too deep. This process forces too much carbon dioxide from our body and creates a chemical imbalance in the blood. The symptoms associated with hyperventilation are: A. dizziness; B. tingling sensation in the fingers and toes; C. increased heart rate; D. blurring of vision; E. Muscle spasms; F. increased sensation of body heat; G Apprehension and mental confusion; H. loss of consciousness. Hyperventilation usually is an involuntary response to a stressful situation, such as tense, anxious, apprehensive, fearful, or overworked. The symptoms of hyperventilation are similar to hypoxia. It is not easy to discriminate between hyperventilation and hypoxia. It is dangerous that we inhale more oxygen when falling into hyperventilation, but we think incorrectly that we were hypoxia. How to diagnose it correctly? If we still feel breathless after we used supplemental oxygen, we should know that we are hyperventilation. Ensuring that the supplemental oxygen equipment is work in proper flow rate, when we use it, maintaining a normal breathing rate when we are in a stressful situation are help to prevent it. Slowing the breathing rate, reducing breathing depth, talking aloud, or breathing into a paper bag of carbon dioxide slowly, are all treatments for hyperventilation. Recovery is usually rapid when the rate of breathing is brought under control.
AlCOHOL AND DRUGS It is well known that pilot's physical and mental skills must be in high-point when he is at the controls, but alcohol and some drugs, even these drugs are used to treat a disease be is suffering, may dull these senses and can reduce his performance to a dangerous level. In this section, we will discuss the hazardous effects of alcohol and the way seemingly harmless drugs can sometimes cause serious problems in the flying environment.
Alcohol Alcohol, such as wine, beer or spirits, is a form of ethyl alcohol which acts as a depressant on the central nervous system. One of the characteristics of alcohol is the amazing speed with which it is absorbed into the body. Unlike most other substances, it does not require digestion, but passes directly into the blood stream. There is some reduction in the rate of absorption if the stomach already contains some foods, especially fatty foods. Once in the blood stream, it is carried almost
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immediately to the brain where it acts as a depressant Often there is a sense of euphoria, accompanied by a false impression that performance is above average. In fact, the individual who has consumed alcohol will become more relaxed and less prone to worry, leading to a decrease in alertness. The alcohol then affects the area of the brain which controls speech and muscular activity, resulting in impairment of speech and muscular coordination. Continuing absorption of alcohol eventually affects all areas of the brain which can lead to coma The adverse effect of alcohol is greatly multiplied when a person is exposed to altitude It has been shown that two drinks on the ground are equivalent to three or four at altitude. Alcohol reduces the amount of oxygen absorbed into our bloodstream. When we drink, our "physiological altitude" is much higher than our actual altitude. The effect of alcohol on physiological altitude is much greater than that of smoking. Also, the body can not metabolize alcohol as easily at higher altitudes, At sea level, the average person takes about three hours to metabolize an ounce of alcohol. After consuming one ounce (31.1 03 g) of alcohol at 12 000 feet, the average person will take nearly four times, longer to metabolize it as compared to sea level. An individual can't speed up the rate at which alcohol leaves the body. Although drinking
while taking food reduces the rate at which alcohol may be absorbed into the bloodstream, it does not affect the rate at which the alcohol is metabolized and removed from the bloodstream. The use of black coffee, steam baths or fresh air will not change the rate of oxidation, and sleeping off the effects of alcohol may actually slow the rate of oxidation because all body functions slow down during sleep. In addition, alcohol also effects the semi-circular canals, which leads to an increase in susceptibility to disorientation and motion sickness. Considering have an adverse effect on pilots' reaction and judgment, this effect is magnified as altitude increases, the FARs require that pilot blood alcohol be less than 0.04% and that eight hours pass between drinking alcohol and piloting an aircraft. If a pilot has a blood alcohol level of 0.04% or greater after eight hours, he can't fly until his blood alcohol falls below that amount. Even though his blood alcohol may be well below 0.04%, you can't fly sooner than eight hours after drinking alcohol. CCAR 121 also order that no person may act or attempt to act as a crewmember of a civil aircraft within 8 hours after the consumption of any alcoholic beverage, or having a blood alcohol level of. 0.04% or higher. So, it is illegal for a crew member to operate when under the influence of alcohol. Drugs Drugs are used to treat fight illnesses, diseases, or to reduce the severity of their symptoms, but at the same time, almost every drugs has side effects. For example, many stomach medicines contain sedatives which can cause blurred vision and reduce our ability to respond and function in a fully alert state. Some analgesics available for the relief of pain, may cause mental confusion, dizziness, a headache, nausea, and vision problem. It is obviously that these drugs may affect flight safety. So, when you are not feeling well or are taking medication, you should ask yourself several 223
key questions to determine your flying status. If yon have an illness, does the condition present a hazard to safe flight? If you are taking a drug for an illness and it wears off during a flight, will it cause an unsafe condition? If you are taking a drug, can the drug produce any side effect that would influence your motor, perceptual, or psychological condition? If the answer to any of these questions is "Yes" or "I don't know'', consult with an aviation medical examiner (AME) before flying. Furthennore, many pilots prefer to drink coffee or tea to ''pick-me-up" in flight, even heavy coffee or tea. But both of them have caffeine, a typical stimulant, which can stimulate the central nervous system and produce an increase in alertness and activity, produce anxiety and drastic mood swings at one time. The later is very dangerous to fly. The speed of caffeine absorbed into the body is quickly, it begins to show up in the bloodstream within five minutes of ingestion, and its effects can last for as long as 14 hours. Too much caffeine can lead to nervousness and sleep disturbances. Other symptoms of a caffeine overdose are increased mental fatigue, muscle tremors, and occasional stomach irritation. Although caffeine use is not prohibited by the CCAR and FARs, we should use it in moderation to avoid the side effects.
SECTION C SITUATION AWARENESS, COMMUNICATION, LEADERSHIP AND DECISION MAKING Human error has been cited as a major factor in the majority of aviation accidents and incidents in the past two decades. Investigations into the causes of air operator accidents have shown that human error is a contributing factor in 60 to 80 percent of all air operator incidents and accidents. Long term research has demonstrated that these events share common characteristics. Many problems encountered by flight crews have very little to do with the technical aspects of operating in a multi-person cockpit. Instead, problems are associated with situation awareness loss, poor group decision making, ineffective communication, inadequate leadership, and poor task or resource management. In 1979. Resource Management on the Flight deck sponsored by the National Aeronautics and Space Administration. This conference was the outgrowth of NASA research into the causes of air transport accidents. The research presented at this meeting identified the human error aspects of the majority of air crashes as failures of interpersonal communications, decision making, and leadership. At this meeting, the label Cockpit Resource Management (CRM) was applied to the process of training crews to reduce ..pilot error" by making better use of the human resources on the flight deck. In this section, we will discuss some basic questions about CRM, such as situation awareness, communication, leadership. and decision making.
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WHAT IS CRM CRM is the abbreviation for Cockpit Resource Management or Crew Resource Management. The application of team management concepts in the flight deck environment was initially known as Cockpit Resource Management As CRM training programs evolved to include cabin crews, maintenance personnel and others, the phrase Crew Resource Management has been adopted. Briefly defined, crew resource management is a process using all available information and resources, i.e. equipment, procedures and people, to achieve a safe and efficient flight operation. CRM training is one way of addressing the challenge of optimizing the human/machine interface and accompanying interpersonal activities. These activities include team building and maintenance, information transfer, problem solving, decision making, maintaining situation awareness, and dealing with automated systems. Effective CRM has the following characteristics: 1) CRM is a comprehensive system of applying human factors concepts to improve crew performance. 2) CRM embraces all operational personnel. 3) CRM can be blended into all forms of aircrew training. 4) CRM concentrates on crew members' attitudes and behaviors and their impact on safety. 5) CRM uses the crew as the unit of training. 6) CRM is training that requires the active participation of all crew members. It provides an opportunity for individuals and crews to examine their own behavior, and to make decisions on how to improve cockpit teamwork.
SITUATIONAL AWARENESS Situational Awareness (SA) is a new, but an important, concept in CRM. It is the key component of safe flight. Some study shows that many accidents are owing to pilot's SA falling or losing, on the other hand, good SA can increase safety, reduce workload, enhance pilot performance, expand the range of pilot operations, and improve decision making. Pilots need to perceive relevant information, integrating various pieces of data in conjunction with operator goals provides an understanding of the meaning of that information. Based on this understanding, future events and system states can be predicted, allowing for timely and effective decision making.
What Is Situational Awareness There are two good definitions about SA. At the 1989 Fifth International Symposium on Aviation Psychology, Douglas Szchwartz stated: "Situation awareness is the accurate perception of the factors and conditions that affect an aircraft and its flight crew during a defined period of time. In simplest terms, it is knowing what is going on around you- a concept embraced to the need to think ahead of the aircraft". In 1993, Mica Endsley gave it a scholarly definition: "Situation
awareness is the perception of the elements in the environment within a volume of time and space, 225
the comprehension of their meaning and the projection of their status in the near future." From these definitions, we can see that building and maintaining better SA is the key to increasing cockpit safety. In general, SA covers five areas: The fJ.rst area gives status information -
the physical state or condition of the airplane, e.g. the
amount of flaps or spoilers, the amount of power being drawn from the engines, the flue states, or the position of the landing gear or flaps. The second area is the position of the airplane in respect to the flight plan, to any natural or man made obstructions, or to any other airplane of interest from an avoidance point of view. The third area is the total external environment, including the present and future weather and details of the aviation infrastructure. The fourth area involves: the time the airplane will meet its next navigational fix; the time it will reach its destination; the time available for holding or diversion; the time limit for the fuel available; the time before the weather will change, etc. The fifth area is the state of the other members of the operating team(the cockpit and cabin crew), the passengers, and even the cargo that might be aboard.
Three Levels of SA In a highly successful effort to better analyze SA incidents, Mica Endsley developed a 3-level taxonomy in 1995. the three levels are: Level 1 -
Failure to correctly perceive the situation;
Level2- Failure to comprehend the situation; Level 3 -Failure to comprehend the situation into the future. Using the taxonomy, ASRS reviewed 113 SA incidents that were reported it and found 169 SA errors. In the 113, 80.2% were classified as Levell errors, 16.9% as Level2 errors, and only 2.9% were classified as Level 3 errors. These findings strongly suggest that Level 1 errors (failure to correctly perceive the situation) need the most attention. There can be several reasons for these errors. One is that the information may be known but temporarily forgotten. The cause may be a shortcoming in the system design, a failure in the communication process or because of inadequate training. The date may have been available but difficult to detect or perceive; or it may have been clearly available but simply missed. The date may have been missed because of distractions, complacency, the narrowing of perception, because of concentration in other areas, or because of a too high task load. SA is not a simple process, and is not the safe and efficient operation of an air transport a simple process.
In the past ten years or more, pilot and flight crew' s SA has been studied widely, such as how to measure our SA, the clues of SA weaken or loss, and how to set up and holding our good SA. In this section, we will give you 10 clues to loss of SA and 10 tips for good SA management 10 Clues to Loss ofSA These clues can warn of an "error chain" in progress -
a series of events that may lead to an
accident. Most accidents involving human error include at least four of these clues. 226
1) Ambiguity-information from two or more sources that doesn't agree. 2) Fixation-focusing on any one thing to the exclusion of everything else. 3) Confusion-uncertainty or bafflement about a situation (often accompanied by anxiety or psychological discomfort). 4) Failure to fly the plan~ everyone is focused on non-flying activities. 5) Failure to look outside-everyone heads down. 6) Failure to meet expected checkpoint on flight plan or profile-ETA, fuel burn, etc.
7) Failure to adhere to standard operating procedures. 8) Failure to comply with limitations, minimums, FARs, etc. 9) Failure to resolve discrepancies- contradictory data or personal conflicts. 10) Failure to communicate fully and effectively- vague or incomplete statements.
10 Tips for Good SA Management 1) Predetermine crew roles for high-workload phases of flight. 2) Develop a plan and assign responsibilities for handling problems and distractions. 3) Solicit input from all crew members including cabin, A TC, maintenance, dispatch, etc. 4) Rotate attention from plane to path to people - don't fixate. 5) Monitor and evaluate current status relative to your plan. 6) Project ahead and consider contingencies. 7) Focus on the details and scan the big picture. 8) Create visual and/or aural reminders of interrupted tasks. 9) Watch for clues of degraded SA. 10) Speak up when you see SA breaking down.
COMMUNICATION Effective communication is the most important of all CRM elements, it is critical to the safe operation of the flight. Human factors issues related to interpersonal communication have been implicated in approximately 70% to 80% of all accidents over the past 20 years. To some extent, communication is the center of all CRM. Communication is the exchange of ideas, information and instruction in an effective and timely manner, so messages are correctly received and clearly understood. Communication is a process of some information transferring, which is possible in many different forms. Through the spoken or written word, through body language, through symbols and gestures and through art and music. No matter what it is, a communication consists of a sender, a massage, and a receiver. For an effective communication, it is important that the receiver can interpret the message and respond accordingly. In this section, we will mainly discuss the spoken word, a form of communication, which is used almost exclusively during flight
A Communication Model Before a communication can take place, a purpose expressed as a message to be conveyed is 227
needed. It passes between a sender and a receiver. The message is encoded (converted to symbolic form) and is passed by way of some medium (channel) to the receiver, who retranslates (decodes) the message initiated by the sender. The result is a transference of meaning from one person to another. Figure 7-14 depicts the communication process. The model is made up of seven parts: the communication source (sender), encoding, message, the channel, decoding, the receiver and feedback.
feedback Figure 7-14 Communication Model
The sender sends a message to the receiver, he/she initiates a message by encoding a thought, four conditions have been described, which affect the encode message: skill, attitudes, knowledge, and the social culture system. The message is the actual physical product from the sender's encoding. It is affected by the code or group of symbols we used to transfer meaning, the content of the message itself, and the decisions we make in selecting and arranging both codes and content. The channel is the medium through which the message travels. it is selected by the sender. The receiver is the object to whom the message is directed. But before the message can be received, the symbols in it must be translated into a form that can be understood by the receiver. This is the decoding of the message. Just as the encoder was limited by his/her skill, attitudes, knowledge, and the social culture system, the receiver is equally restricted. The feedback loop is the final link in the communication process. Feedback is the check on how successful we have been in transferring our message as ordinary intended. It determines whether understanding has been achieved. That's to say, we can use it to put the message back into the system as a check against misunderstanding.
Verbal and Non-verbal Communication In general, there are two types of communication, verbal and non-verbal communication. Verbal communication is the use of words and language to give and receive information. Language is inextricably linked with the cognitive or thinking processes as well as with communication. Interpersonal relationships are influenced by the manner of speech as well as by the content. The manner or paralanguage includes voice pitch, word stress, timing and pauses. This can cause difficulties when communicating in a language which is not native language to the speaker, such as may occur ewe in the use of English as the international aviation language. Non-verbal communication is also known as body language. This involves communication using eye contact, facial expression, touch, body orientation and posture, hand and head movement,
228
and physical separation.
Communication Barriers Whether a communication is available or not is not only depending on the characteristic of the information itself, but also lying communicators' mental trait, such as apperception, memory, thinking, personality, and etc. The background of the communication affect its validity too. Factors that can inhibit effective communication can be external or internal. External factors are the most obvious, they include high environmental noise levels, distractions of a busy work environment or physical discomfort, and poor enunciation or an unfamiliar accent Internal factors are mainly associated with the perception of what is said. A message spoken with perfect enunciation and clarity can still be misunderstood if the receiver misinterprets its intended meaning. One of the most common internal factors is the error of expectancy. This occurs when the receiver assumes that he has heard what he expects to hear rather than what has actually been said. In some cases the receiver listens to part of the message which says what is expected, but fails to register other information that may be relevant "Authority gradient'' is an important factor that can have an effect on communication in a multi-crew environment. This concept is used to describe the composing of flight crew. Authority gradient refers to the difference of rank, ability, longevity and status between the captain and the other members of the flight crew. No matter authority gradient is too steep or too shallow, it is not beneficial to flight safety. If the authority gradient too steep, the captain may assume total command leaving the first officer out of the "loop''. The first officer may be unlikely to contribute anything to the decision making process- even when he is sure that the captain has made a mistake! If the authority gradient too shallow, the caption may consult the first officer on every issue and may never take command. In an emergency it is likely that no clear cut decision will be made. In a flight crew, an apt arranging is the caption's power, ability, longevity and status is higher than the other members of the flight crew in some short. In this arrangement, the captain can assume overall command but involves the first officer as a useful member of a team which he leads. The first officer respects the captain's command status but feels :free to contribute.
Effective Communication Poor crew communication can lead to misunderstandings that may result in crew error. In order to ensure flight safety, we must know how to avoid misunderstanding, and make an effective communication. Generally speaking, an effective communication requires skill in inquiry, advocacy and an awareness of potential communication barriers. Using of standard phrases, thinking before you speak, keeping control over the pace and clarity of speech, avoiding the effect of motion, are helpful for effective communication. Moreover. fight crew is matched reasonable, the captain has good leadership. the other flight crew member can recognize his/her role in assuring the flight safety. these are all benefit to enhance communication effective.
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LEADERSHIP In modem civil aviation, most flight operations should be a team activity. A flight crew is a team, although it is small, it still has leader and followers. According to the rules, the captain takes charge the aircraft, he /she will be the leader of the flight deck group by virtue of status, the other flight members should be the followers. A leader in a given situation is a person whose ideas and actions influence the thought and behavior of others. A leader uses example and persuasion combined with a personal understanding ofthe goals and desires of the group be/she happens to be leading as well as those of the employer. A leader feels responsible for trying to implement these goals, he should take the initiative to promote teamwork and professionalism, foster a productive staff climate, mentor other staff members to improve their skills and abilities, demonstrate standards of professionalism and resolve conflict.
Authoritative and Participatory There are many different definitions of leadership. Authoritative and participatory are the more broadly accepted types of leadership. Authoritative is derived from the word "authority" . An authoritative leader tends to make all team decisions and controls all resources because the team is structured as a hierarchy. A hierarchical structure is one in which many levels of management exist and there is a clearly defined boss. But true leadership is not equal to authority. Whereas authority is usually assigned, true leadership is acquired. The status of authority has effect immediately it is assigned, but the quality of leadership takes time to develop. People who are leaders will be automatically granted authority by the group, while people in authority often show no trace of leadership. A participatory leader allows each team member to have a say and to participate in team processes. The team leader is more egalitarian, or equal, under participatory leadership than with an authoritative leader. The participatory leader may, however, ultimately decide the team's actions, but takes into consideration the team members' experience, knowledge, and preferences. Whether one form of leadership is better than another form? The answer to that question_ usually depends on the organization of the team and the task being performed. For example, a fully participative team where a vote is taken and every team member surveyed on every little detail of the workday would be unable to perform their duties in a timely manner. However, an overly authoritative supervisor or manager who fails to request input from anyone may suppress the free flow of ideas and dictate team activities that negatively impact safety. Good leadership is a balancing act between the two, he should recognize different behavioral styles and balance concern for people with concern for performance.
In summary, a good leader should: A. Lead by example. Set high standards of performance by demonstrating a high level personal performance. 230
B. Advise intent Communicate with the team and keep them informed of intentions before acting on those decisions. C. Delegate. Delegate appropriate duties to team members to allow time for the leader to perform a monitoring or supervising roll. D. Motivate. One of the most effective means of motivation is to offer praise for good performance (Positive reinforcement). E. Consult. Involve the team in most decision making processes. F. Set priorities. The most efficient use of resources is achieved when energy is directed to tasks in a logical order of priority. Most students have heard it summed up by the slogan "aviate, navigate, communicate."
Management Styles Management styles, is another good description of leader's behavior. A leader may be taskoriented or relationship-oriented, or may combine elements of both depending on individual personality. A leader at the extreme of task orientation will show a style which may be dominant, opinionated, aggressive and stubborn. Conversely, a leader at the relationship extreme of orientation
will demonstrate a style which is practical, trusting, friendly, accommodating, but does not voice qualms. Blake and Mouton integrated the ideas of task and relationship orientations into a grid with five main styles. It is based on the concept that leaders vary (from 1 to 9) in their concern for people (relationships) and their concern for getting things done (tasks) (See Figure 7 -15).
1.9
9.9
5.5
1.1
9.1 Concern for production
Figure 7-15 Managerial Grid
9.1 Authority-Obedience: The leader's maximum concern is for task completion and is combined with a minimum concern for people, i.e., dictation to followers what they 231
should do and how they should do it. 1.9 "Country Club" Management: The leader shows a minimum concern for getting tasks completed, but a maximum concern for people. 1.1 Impoverished Management: The leader has a minimum concern for both production and people and puts forth only the least effort required to remain in the organization. 5.5 "Organization Man" Management: The leader does what is minimally ex.-pected, which results in conformity to the status quo. 9.9 Team Management: The leader integrates the concern for production and the concern for people at a high lever; is goal centered; and seeks results through the participation, involvement and commitment of all those who can contribute. This model of leadership was developed as a guide for managers who deal with multiple subordinates. The ideal leader will have a style which combines the extremes of either orientation and will be confident and relaxed, communicate and involve others, accept criticism, and be technicaUy competent. Powers of command will be exercised in a way which gains the respect and commitment of all crew members, generating an atmosphere in which all members of the team feel that they are actively and positively contributing to the achievement of the goal.
Followers hip Any team must have both a leader and followers. A follower is a member of the team that is being led. In a flight crew, a follower should be anyone except the captain. Followership is a new term, which covers the ability to be a good team player and the ability to effectively help a recognized leader. A leader displays leadership by directing operations \Vith confidence, gaining trust and cooperation, and inviting initiatives from the other crew members while ensuring task completion. A follower displays followership by inquiring, advocating. critiquing and through practices such as planning ahead to preclude surprises, anticipating requirements and being ready to provide input to support the leader. A survey conducted in the UK revealed that 93% of first officers and 74% of captains admitted that there were other pilots with whom they preferred not to work. As a team member, you may not always has the luxury of working only with those that you genuinely like. To be an effective team member, you must be able to put personality differences aside and still contribute effectively to the task goals. A good team member will not agree with a plan of action just to ''keep the peace" if he/she is feeling uneasy about it. On the other hand, once an appropriate plan of action has been decided upon, a good term member will fully support it if he/she might personally prefer a different plan. The degree of assertiveness displayed by a particular team member is controlled to a very great extent by that person's personality, however if you are convinced that a particular course of action is incorrect or dangerous. It is vital that you put your opinion forward for consideration. Just as we have discussed, decision making is the key to safety. The leader, in general, has final responsibility and authority for decision making, but all other members must participate in the decision-making 232
;:rocess as necessary and time permitting. Many of the worlds worst aviation disasters may have :)een avoided if the first office or other crew member had strongly voiced their objections to a bad decision. There are something we should notice that the position of leader and the follower may be changed in some special conditions. Captains can become followers, and followers can become captains. While remaining overall leader of the flight crew, the captain might not be the leader in a specific circumstance in which another member of the team has great knowledge. For example, the first office has a great deal of experience with a particular airport as compared to the captain. Soliciting inputs and utilizing this experience from other crewmembers can be a confidence-building situation for all concerned, yet it does not mean that the captain has relinquished his command. More precisely, the captain is making good use of the resources in the cockpit It might also be mentioned that this type of leadership behavior by the captain is radically different from that of the stereotypic autocratic captain. So, it is right that some people say a good leader also has the ability to act as a good follower.
DECISION MAKING Decision making is the process of determining and implementing a course of action and evaluating the outcome. Act as a special conveyance, flying is a combination of events which requires pilots to make a continuous stream of decisions. Especially, when we find that something has changed or that an expected change did not occur, it is needed. The decision making process is shaped by the type of problem, degree of threat, time available and resources. During any job there are many opportunities for decision making, ranging from simple to complex. and from short-term to long-term. Experience plays a large part in our decision making process by enhancing our ability to define possible threats and generate a safe course of action. The decision making process also encompasses the ability to handle errors that we may or may not have experience handling. Decision making can be known in two ways: On the one hand, it is an ability to search for and establish the relevance of all available information regarding a flight situation, to specify alternative courses of action. and to determine expected outcomes from each alternative. From it, we can see that pilots decision making refers to intellectual capabilities, it relies on our abilities to sense, store, retrieve, and integrate information. This part of decision making is purely rationaL On the another hand, it is a motivation to choose and authoritatively execute a suitable course of action within the time frame permitted by the situation, which implies that, in part, our decisions are based on tendencies to use other than safety-related information when choosing courses of action. For example, pilots might consider such items as job demands, convenience, monetary gain, and self-esteem before taking action. Decide
The decision-making process is quite complex; however, it can be condensed into six elements, 233
using the acronym DECIDE. The steps in the DECIDE process are as follows: D -Detect the fact that a change has occurred; E -Estimate the need to counter or react to the change; C- Choose a desirable outcome for the success of the flight; I - Identify actions which could successfully control the change; D -Do the necessary action to adapt to the change; E- Evaluate the effect of the action.
Hazardous Attitudes There are five hazardous attitudes which affect pilot decision making Anti-authority: "Don't tell me what to do, I'll do it my way!" - People with this attitude may refuse to listen to the advice or suggestions of others, or they may just regard rules, regulations, and procedures as silly or unnecessary. Impulsivity: ''Do something quickly!"- This is the thought pattern of people who frequently feel the need to do something immediately. They do not stop to consider what they are about to do So they can select the best alternative, they do the first thing that comes to mind. Invulnerability: "It won't happen to me!"- Many people feel that accidents happen to others but never to them. Pilots who think this way are more likely to take chances and run unnecessary risks. Macho: "There's nothing I can't do", "there's nothing I won't try!" - These people are always trying to prove that they are better than anyone else by taking risks and by trying to impress others. Resignation: "What's the use?"- This is an unwillingness to take control of a situation and do something different when the unexpected happens. People with this attitude do not see themselves as making a great deal of difference in what happens to them. When things go well, they ~''That's good luck." When things go badly, they attribute it to bad luck or feel that someone is "out to get them" They have the action to others for better or worse.
Antidotes for Hazardous Attitudes There are ways to overcome the five major hazardous attitudes which contribute to poor pilot decision making. One way is to become thoroughly aware of them by studying the preceding paragraphs, another is to use antidotes. By telling yourself something to counteract the hazardous attitude, you're ''taking an antidote". Learn to recognize a hazardous attitude, correctly label the thought, and then say its antidote to yourself(See Figure 7-16).
The False Hypothesis One of the most common contributors to human error in the decision making process is the false hypothesis or mistaken assumption. No pilot would deliberately commence a take-off without a clearance, however there are countless cases on record when the pilot bas falsely assumed that a clearance has been given. 234
I
HAZARDOUS Anti-authority Impulsivity
"Don't tell me what to do!" "Do something- quickly!"
Invulnerability Macho
"It won't happen to me!"
"There's nothing I can't do!"
Resignation
"What's the use?"
ANTIDOTE "Follow the rules, they are usually right." "Not so fast, think first." "it could happen to me." "taking chances is foolish." "I'm not helpless, I can make a difference."
Figure 7-16 _To Overcome Hazardous Attitudes
High expectancy: A good example of this is provided by the world's worst aviation accident occurred when two Boeing 747s collided on the runway at Tenerife in 1977 after one of the captains made such an assumption. Analysis of a number of aviation and railway accidents shows that there are certain situations in which the false hypothesis is most likely to occur.
Diverted attention: When the pilot is preoccupied with one problem, a false assumption is made about the status of other systems. Many a pilot has grappled with a radio problem in controlled airspace only to end up landing with the wheels up. There is one case of an airline crew who run out of fuel while trying to solve a problem with an undercarriage warning light!
When it serves as a defense: This involves accepting the assumption which promises the happiest outcome and ignoring or evading the truth. A pilot accepts any evidence that the weather is likely to improve while rejecting any evidence to the contrary.
Following a period of high concentration: After coping with a demanding or dangerous in-flight situation there is a tendency to relax. A pilot who bas just landed after coping with an engine failure in a light twin turns off the runway and taxies into a ditch!
As a result of the effects of a motor memory: An action involving the operation of a lever or switch which selects the wrong one or operates it in the incorrect sense. The pilot of a light twin was asked to make the best possible speed on approach to assist in traffic separation. He obliged by retracting the undercarriage and increasing the approach speed. He then proceeded to land with the gear still up.
235
CHAPTER 8 AVIATION METEOROLOGY Weather -
the state of the atmosphere, at any given time and place strongly influences our
daily routine as well as our general life patterns. VIrtually all of our activities are affected by weather, but in all man's endeavors, none is influenced more intimately by weather than aviation. Weather is one in the most important factors that influence airplane performance and flying safety.
SECTION A
BASIC THEORIES
THE ATMOSPHERE Heat and Temperature The primary cause of all the Earth's weather is the variation in solar radiation received at the surface. The amount of solar energy received by any region varies with time of day, with seasons, and with latitude. These differences in solar energy create temperature variations. Temperatures also vary with differences in topographical surface and with altitude. These temperature variations create forces that drive the atmosphere in its endless motions. Our restless atmosphere is constantly in motion as it strives to reach equilibrium. These never-ending air movements set up chain reactions which culminate in a continuing variety of weather. When two surfaces are heated unequally, they heat the overlying air unevenly. The warmer air expands and becomes lighter or less dense than the cool air. The more denser, cool air is drawn to the ground by its greater gravitational force lifting or forcing the warm air upward much as oil is forced to the top of water when the two are mixed: The rising air spreads and cools, eventually descending to complete the convective circulation. Convection of both large and small scales accounts for systems ranging from hemispheric circulations down to local eddies.
Vertical Structure We classify the atmosphere into layers, or spheres, by characteristics exhibited in these layers -temperature lapse rate. The decrease of temperature with altitude is defmed as lapse rate. Figure 8-1 shows one division. The atmosphere was divided into four layers: troposphere (A), stratosphere (B), mesosphere (C) and thermosphere (D). All air carrier flights take place in the two low-levels of the atmosphere. These are the troposphere and the stratosphere. The troposphere is the layer from the surface to an average altitude of about 7 miles. It is characterized by an overall 236
decrease of temperature with increasing altitude- at an average in two degrees Celsius per one thousand feet of altitude. The height of the troposphere varies with latitude and seasons. It slopes from about 20 000 feet over the poles to about 65 000 feet over the equator; and it is higher in summer than in winter. The stratosphere is typified by relatively small changes in temperature with height except for a warming trend near the top.
The stratosphere extends from the top of the
troposphere to about 26 to 29 miles altitude. At the top of the troposphere is the tropopause, a very
thin layer marking the boundary between the troposphere and the layer above. An abrupt change in the temperature lapse rate characterizes the tropopause. It acts as a lid to confme most of the water vapor. This, in tum, keeps most of the weather below the tropopause. The height of the tropopause and certain weather phenomena are related. Temperature and wind vary greatly in the vicinity of the tropopause affecting efficiency, comfort, and safety of flight. Maximum winds generally occur at levels near the tropopause. These strong winds create narrow zones of wind shear which often generate hazardous turbulence. Preflight knowledge of temperature, wind, and wind shear is important to flight planning.
Figure 8-1 Vertical Structure of Atmosphere
237
THE WIND AND WIND FORMING FORCES Atmospheric pressure is the force per unit area exerted by the weight of the atmosphere. Pressure varies with altitude and temperature of the air
as well
as other minor influences. Five
pressure systems are defined as follow: A. LOW- a center of pressure surrounded on all sides by higher pressure; also called a cyclone. B. HIGH- a center of pressure surrounded on all sides by lower pressure; also called a anticyclone. C. TROUGH- an elongated area of low pressure with the; owest pressure along a line marking maximum cyclonic curvature. D. RIDGE- an elongated area of high pressure with the highest pressure along a line marking maximum anticyclonic curvature. E. COL- the neutral area between two highs and two lows. It also is the intersection of a trough and a ridge. Pressure differences must create a force, which drives the wind. This force is the pressure gradient force. The force is from higher pressure to lower pressure and is perpendicular to isobars or contours. Another major influence in the wind direction is a phenomenon known as Coriolis effect. The fo:-ce deflects air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere as showed in Figure 8-2. Coriolis force is at a right angle to wind direction and directly proportional to wind speed. As wind speed increases, Coriolis force increases. At a given latitude, double the wind speed and
Figure 8-2 Coriolis Force
you double the Coriolis force. Coriolis force varies with latitude from zero at the equator to a maximum at the poles. It influences wind direction everywhere except immediately at the equator; but the effects are more pronounced in middle and high latitudes. The instant air begins moving, Coriolis force deflects it to the right. Soon the wind is deflected a full 90° and is parallel to the isobars or contours. At this time, Coriolis force exactly balances pressure gradient force. As the air tries to blow outward from the high pressure, it is deflected to the right by the Coriolis force. Thus, the wind around a high blows clockwise. The high pressure with its associated wind system is an anticyclone. The wind around a low is counterclockwise. The low pressure and its wind system is a cyclone. Wmd flow patterns aloft follow isobars or contours where friction has little effect, showed in Figure 8-3. We cannot, however, neglect 238
Figure 8-3 Wind Flow Patterns Aloft
t:ction near the surface. As frictional force slows the windspeed, Coriolis force decreases. However, ::':iction does not affect pressure gradient force. Pressure gradient and Coriolis forces are no longer .:1 balance.
The stronger pressure gradient force turns the wind at an angle across the isobars toward
.ower pressure until the three forces balance. Frictional forces and Coriolis forces combine to just ::oalance pressure gradient force. You can determine wind direction from a weather map. If you face along an isobar or contour with lower pressure on your left, wind will be blowing in the direction you are facing. On a surface map, wind will cross the isobar at an angle toward lower pressure; on
:m upper air chart, it will be parallel to the contour.
THE GENERAL CIRCULATION Because of uneven heating of the Earth, surface pressure is low in warm equatorial regions and high in cold polar regions. A pressure gradient develops from the poles to the equator. As air is forced aloft at the equator and begins its high-level trek northward, the Coriolis force turns it to the right or to the east. Wind becomes westerly at about 30°latitude temporarily blocking further northward movement. Similarly, as air over the poles begins its low-level journey southward toward the equator, it likewise is deflected to the right and becomes an east wind, halting for a while its southerly progress. As a result, air literally "piles up" at about 30°and latitude in both hemispheres. The added weight of the air increases the pressure into semipermanent high pressure belts. The high pressure belt at about 30°north latitude forces air outward at the surface to the north and to the south. The northbound air becomes entrained into the midlatitude storms. The southward moving air is again deflected by the Coriolis force becoming the well-known subtropical northeast trade winds. In midlatitudes, high level winds are predominantly from the west and are known as the prevailing westerlies. Polar easterlies dominate low-level
34 - - - / /
circulation north of about 60°latitude. Northeasterly
trade
winds
carry
tropical storms from east to west. The prevailing westerlies drive midlatitude storms generally from west to east (see
-
/
_.,
---------------/ / /
/
EQUATOR
Figure 8-4 The General Circulation in the Northern Hemisphere and Surface Wind Belts
Figure 8-4).
STABLE AND UNSTABLE AIR Anytime air moves upward, it expands because of decreasing atmospheric pressure. Conversely, downward moving air is compressed by increasing pressure. But as pressure and volume change, temperature also changes. When air expands, it cools; and when compressed, it warms. These changes are adiabatic, meaning that no heat is removed from or added to the air. The adiabatic rate of change of 239
temperature is virtually fixed in unsaturated air but varies in saturated air. Unsaturated air moving upward and downward cools and warms at about 3.0 ·c per 1 000 feet. This rate is the "dry adiabatic rate of temperature change" and is independent of the temperature of the mass of air through which the vertical movements occur. When the air flows downslope, the air is no longer saturated; it will heat at the nonnal dry rate. An example of this is the "katabatic wind" which becomes warmer and dryer. Condensation occurs when saturated air moves upward. Latent heat released through condensation partially offsets the expansionary cooling. Therefore, the saturated adiabatic rate of cooling is slower than the dry adiabatic rate. The saturated rate depends on saturation temperature or dew point of the air. When moist air is forced upward, the temperature and the dew point converge on each other at a rate of about 2.5 ·c per 1 000 feet. At the altitude where the dew point lapse rate and the dry adiabatic rate meet, cloud bases will form. If the upward moving air becomes colder than surrounding air, it sinks. The air is said to be stable, but if it remains warmer, it is accelerated upward as a convective current. If this happens, the air is said to be unstable. Whether it sinks or rises depends on the ambient or existing temperature lapse rate. The difference between the existing lapse rate of a given mass of air and the adiabatic rates of cooling in upward moving air determines if the air is stable or unstable. An easy way to judge is: if the temperature drops rapidly as the altitude increases, the air is unstable; if the temperature remains unchanged or decreases only slightly as altitude is increase, the air mass is stable. If the temperature actually increases as altitude increases, a temperature inversion exists. This is the most stable of weather conditions. A stable atmosphere resists any upward or downward displacement. An unstable atmosphere allows an upward or downward disturbance to grow into a vertical or convective current.
CLOUDS AND PRECIPITATION Clouds, to almost everyone, have some meaning. But to you, a pilot, clouds are your weather "signposts in the sky". They give you an indication of air motion, stability, and moisture. Clouds help you visualize weather conditions and potential weather hazards you might encounter in flight.
Identification For identification purposes, you need be concerned only with the more basic cloud types, which are divided into three ''families". The families are: high clouds, middle clouds, low cloud. The first two families are further classified according to the way they are formed. The third family includes with extensive vertical development clouds. These clouds formed vertical currents in unstable air are cumulus meaning accumulation or heap; they are characterized by their lumpy, billowy appearance. Clouds formed by the cooling of a stable layer are stratus meaning stratified or layered; they are characterized by their uniform, sheet-like appearance.
In addition to the above, the prefix nimbus or the suffix nimbus means rain cloud. Thus,
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stratified clouds from which rain is falling are nimbostratus. A heavy, swelling cumulus type cloud which produces precipitation is a cumulonimbus. Clouds broken into fragments are often identified by adding the suffix fractus; for example, fragmentary cumulus is cumulus fractus. High Clouds The high cloud family is cirriform and includes cirrus, cirrocumulus, and cirrostratus. They are composed almost entirely of ice crystals. The height of the bases of these clouds ranges from about 16 500 to 45 000 feet in middle latitudes.
Middle Clouds The middle cloud family are the altostratus and the altocumulus clouds. These clouds are primarily water, much of which may be supercooled. The height of the bases of these clouds ranges from about 6 500 to 23 000 feet in middle latitudes.
Low Clouds The low cloud family are the stratus, stratocumulus, nimbostratus clouds and fair weather cumulus clouds and extensive vertical development clouds. Low clouds are almost entirely water, but at times the water may be supercooled Low clouds at subfreezing temperatures can also contain snow and ice particles. The bases of these clouds range from near the surface to about 6 500 feet in middle latitudes. The vertically developed family of clouds includes towering cumulus and cumulonimbus. These clouds usually contain supercooled water above the freezing level. But when a cumulus grows to great heights, water in the upper part of the cloud freezes into ice crystals forming a cumulonimbus. The heights of cumuliform cloud bases rang from 1 000 feet or less to above 10 000 feet
Signposts in the Sky Cirrus are thin, feather-like ice crystal clouds in patches or narrow bands. Larger ice crystals often trail downward in well-defined wisps called "mares'tail". Wispy, cirrus-like, these contain no significant icing or turbulence. Dense, banded cirrus, which often are turbulent, are associated with jet stream. See Appendix Figure 1. Cirrocumulus are thin clouds, the individual elements appearing as small white flakes or patches of cotton. They may contain highly supercooled water droplets, some turbulence and icing. See Appendix Figure 2. Cirrostratus is a thin whitish cloud layer appearing like a sheet or veil. Cloud elements are diffuse, sometimes partially striated or fibrous. Due to their ice crystal makeup, these clouds are associated with halos-large luminous circles surrounding the sun or moon. No turbulence and little if any icing .The greatest problem flying in cirriform clouds is restriction to visibility. They can make the strict use of instruments mandatory. See Appendix Figure 3. Altocumulus are composed of white or gray colored layers or patches of solid cloud. The cloud elements may have a waved or roll-like appearance. Some turbulence and small amounts of icing. See Appendix Figure 4.
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Altostratus is a bluish veil or layer of clouds. It is often associated with altocumulus and sometimes gradually merges into cirrostratus. The sun may be dimly visible through it. Little or no turbulence with moderate amounts of ice. See Appendix Figure 5. Altocumulus castellanus are middle level convective clouds. They are characterized by their billowing tops and comparatively high bases. They are a good indication of mid-level instability. Rough turbule~ce with some icing. Standing lenticular altocumulus clouds are formed on the created by barriers in the wind flow. The clouds show little movement, hence the name standing. Wind, however, can be quite strong blowing through such clouds. They are characterized by their smooth, polished edges. The presence of these clouds is a good indication of very strong turbulence and should be avoided. See Appendix Figure 6 Nimbostratus is a gray or dark massive cloud layer, diffused by more or less continuous rain, snow, or ice pellets. It may merge into very low stratus or stratocumulus. But very little turbulence can pose a serious icing problem if temperatures are near or below freezing. See Appendix Figure 7. Stratus is a gray, uniform, sheet-like cloud with relatively low bases. When associated with fog or precipitation, the combination can become troublesome for visual flying. Little or no turbulence, but temperatures near or below freezing can create hazardous icing conditions. See Appendix Figure 8. Stratocumulus bases are globular massed or rolls unlike the flat ,sometimes indefinite, bases of stratus. They usually form at the top of a layer mixed by moderate surface winds. Sometimes, they form from the breaking up of stratus or the spreading out of cumulus. Some turbulence, and possible icing at subfreezing temperatures. Ceiling and visibility usually better than with low stratus. See Appendix Figure 9. Fair weather cumulus clouds form in convective currents and are characterized by relatively flat bases and dome-shaped tops. Fair weather cumulus do not show extensive vertical development and do not produce precipitation. More often, fair weather cumulus indicate a layer of instability. Some turbulence and no significant icing. See Appendix Figure 10. Towering cumulus signifies a relatively deep layer of unstable air. It shows considerable vertical development and has billowing cauliflower tops. Showers can result from these clouds. Very strong turbulence; some clear icing above the freezing level. See Appendix Figure 11. Cumulonimbus are the ultimate manifestation of instability. They are vertically developed clouds of large dimensions with dense boiling tops often crowned with thick veils of dense cirrus(the anvil). Nearly the entire spectrum of flying hazards are contained in these clouds including violent turbulence. They should be avoided at all times! This cloud is the thunderstorm cloud and is discussed in detail in SECTION H, ''Thunderstorms". See Appendix Figure 12.
Precipitation Precipitation is an all inclusive term denoting drizzle, rain, snow, ice pellets, hail, and ice 242
crystals. Precipitation occurs when these particles grow in size and weight until the atmosphere no longer can suspend them and they fall. Precipitation forming and remaining liquid falls as rain or drizzle. Sublimation forms snowflakes, and they reach the ground as snow if temperatures remain below freezing. Precipitation can change its state as the temperature of its environment changes. Falling snow may melt in warmer layers of air at lower altitudes to form rain. Rain falling through colder air may become supercooled, freezing on impact as freezing rain; or it may freeze during its descent, falling as ice pellets. Ice pellets always indicate freezing rain at higher altitude. To produce significant precipitation, clouds usually are 4 000 feet thick or more. The heavier the precipitation, the thick the clouds are likely to be. When arriving at or departing from a terminal reporting precipitation of light or greater intensity, expect clouds to be more than 4 000 feet thick.
WEATHER SYSTEMS Air Mass When a body of air comes to rest or moves slowly over an extensive area having fairly uniform properties of temperature and moisture, the air takes on those properties. Thus, the air over the area becomes somewhat of an entity and has fairly uniform horizontal distribution of its properties. The area over which the air mass acquires its identifying distribution of moisture and temperature is its "source region''. Just as air mass took on the properties of its source region, it tends to take on properties of the underlying surface when it moves away from its source region, thus becoming modified. The degree of modification depends on the speed with which the air mass moves, and the temperature difference between the new surface and the air mass. Cool air moving over a warm surface is heated from below, generating instability and increasing the possibility of showers. Warm air moving over a cool surface is cooled from below, increasing stability. If air is cooled to its dew point, stratus and/or fog forms. Stability of an air mass determines its typical weather characteristics. When one type of air mass overlies another, conditions change with height. Characteristics typical of an unstable are: 1) cumuliform clouds, 2) showery precipitation, 3) rough air (turbulence), 4) good visibility, except in blowing obstructions; characteristics typical of an stable are : 1) stratiform clouds and fog, 2) continuous precipitation, 3) smooth air, 4) fair to poor visibility in haze and smoke.
Fronts As air masses move out of their source regions, they come in contact with other air masses of different properties. The zone between two different air masses is a frontal zone or front. Across this zone, temperature, humidity and wind often change rapidly over short distances. The formation of a front is called frontogenesis. When a front dissipates, the area experiences frontolysis. A front lies in a pressure trough, and pressure generally is higher in the cold air. Thus, when you cross a front directly into colder air, pressure usually rises abruptly. When you approach a front toward warm air, pressure generally falls until you cross the front and then
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remains steady or falls slightly in the warm air. Wmd always changes across a front. Wind flows around a front more or less parallel to the front, and in a counterclockwise direction. As an aircraft flies toward a front in the northern hemisphere, the pilot will notice a decreasing pressure and a wind from the left of the aircraft. After passing through the front, the pilot will note a wind shift to the right and increasing air pressure.
Types ofFronts The leading edge of an advancing cold air mass is a cold front. At the surface, cold air mass is a cold front. At the surface, cold air is overtaking and replacing warmer air. Cold fronts move at the speed of the wind component perpendicular to the front just above the frictional layer. The edge of an advancing warm air mass is a warm front- warmer air is overtaking and replacing colder air. Since the cold air is denser than the warm air, the cold air hugs the ground. The warm air slides up and over the cold air and lacks direct push on the cold air. Thus, the cold air is slow to retreat in advance of the warm air. This slowness of the cold air to retreat produces a frontal slope that is more gradual than the cold frontal slope. Consequently, warm fronts on the surface are seldom as well marked as cold fronts, and they usually move about half as fast when the general wind flow is the same in each case. When neither air mass is replacing the other, the front is stationary. The opposing forces exerted by adjacent air masses of different densities are such that the frontal surface between them shows little or no movement In such cases, the surface winds tend to blow parallel to the frontal zone. Slope of a stationary front is normally shallow, although it may be steep depending on wind distribution and density difference. Stationary fronts or slow moving cold fronts can form frontal waves and low pressure areas. A small disturbance can cause a bend in the frontal line that induces a counterclockwise flow of air around a deepening low pressure area The wave forms into a warm front followed by a cold front. The cold front can then overtake the warm front and force the warm air between the two aloft. This is called an occluded front or an occlusion. Most fronts mark the line between two air masses of different temperature. However, this is not always the case. Sometimes, air masses with virtually the same temperatures will form a front. The only difference between the two is the moisture content. The front formed in such conditions is called point front or a dry line. The surface position of a front often marks the line where an arctic and a tropical air mass meet at the surface. Frontal Weather In fronts, flying weather varies from virtually clear skies to extreme hazards including hail, turbulence, icing, low clouds, and poor visibility. Weather occurring with a front depends on 1) the amount of moisture available, 2) the degree of stability of the air that is forced upward, 3) the slop of the front, 4) the speed of frontal movement, and 5) the upper wind flow. 1) Cold Front In the northern hemisphere, cold fronts are usually oriented in a northeast to southwest line and may be several hundred miles long. Movement is usually in an easterly direction. 244
:be speed of a cold front usually dictates the type of weather associated with the front However, :here are some general weather characteristics that are found in most cold fronts. These include: 1) cumulus cloud; 2) turbulence; 3) showery precipitation; 4) strong, gusty winds; 5) clearing skies and good visibility after the front passes. Fast-moving cold fronts are pushed along by intense high pressure systems located well behind the front. Surface friction acts to slow the movement of the front, causing the leading edge of the front to bulge out and to steepen the front's slope. These fronts are particularly hazardous because of the steep slop and wide differences in moisture and temperature between the two air masses, as showed in Figure 8-5. When a cold front pushes into extremely moist, unstable air, a squall lines often forms ahead of the front itself. It contains weather more severe than that found along the front The weather usually clears quickly behind a COLO AIR cold front You will often notice reduced cloud cover, improved visibility, lower Figure 8-5 A Faster Moving Cold Front Underruning temperatures, and gusty surface winds Warm, Moist, UllStable Air. following the passage of a fast-moving cold front. The leading edge of a slow-moving cold front is much shallower than that of a fast-moving front. This produces clouds which extend far behind the surface front. A slow-moving cold front meeting stable air usually causes a broad area of stratus clouds to form behind the front. When a slow-moving cold front meets unstable air, large numbers of vertical clouds often form at and just behind the front Fair weather cumulus clouds are often present in the cold air, well behind the surface front. 2) Warm Fronts The slope of a warm front is very gradual, and the warm air may extend up over the cool air for several hundred miles ahead of the front. Some of the common weather patterns found in a typical warm front include: 1) stratus clouds, if the air is moist and stable; 2) little turbulence, except in an unstable air mass; 3) precipitation ahead of the front; 4) poor visibility with haze or fog; 5) wide area of precipitation. The stability and moisture content of the air in a warm front determines what type of clouds will form. If the air is warm, moist, and stable, stratus cloud will develop, showed in Figure 8-6. If the air is warm, moist, and unstable, cumulus clouds will develop. 3) Other Fronts The weather in a stationary front is usually light, somewhat like a warm front. If the air lifted by front is stable and the temperature in clouds does not suit for icing, the weather in a stationary front is very good for flight training in complex weather conditions. Since an occluded front develops when a cold front overtakes a warm front, weather with an occluded front is a combination of both warm and cold frontal weather. So it is even worse than the weather in a single cold front or warm front 245
Higbtlkm
8
6
4 2 0
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Figure 8--6 A Warm Front with Overrunning Moist, Stable Air.
Pressure Systems and Weather At the surface when air converges into a low, it can neither go outward against the pressure gradient, nor can it go downward into the ground; it must go upward. Therefore, a low or trough is an area of rising air. Rising air is conducive to cloudiness and precipitation; thus we have the general association of low pressure-bad weather. By the similar reason, air moving out of a high or ridge depletes the quantity of air. Highs and ridges, therefore, are areas of descending air. Descending air favors dissipation of cloudiness; hence the association, high pressure-good weather. Many times weather is more closely associated with an upper air pattern than with features shown by the surface map. Although features on the two charts are related, they are seldom identical. A weak surface system often loses its identity in the upper air pattern, while another system may be more evident on the upper air chart than on the surface map. Widespread cloudiness and precipitation often develop in advance of an upper trough or low. A line of showers and thunderstorms is not uncommon with a trough aloft even though the surface pressure pattern shows little or no cause for the development. On the other hand, downward motion in a high or ridge places a "cap" on convection, preventing any upward motion. Air may become stagnant in a high, trap moisture and contamination in low levels, and restrict ceiling and visibility. Low stratus, fog, haze, and smoke are not uncommon in high pressure areas. However, a high or ridge aloft with moderate surface winds most often produces good flying weather. Highs and lows tend to lean from the surface into the upper atmosphere. Due to this slop, winds aloft often blow across the associated surface systems. Upper winds tend to steer surface systems in the general direction of the upper wind flow. A contrasting analogy to the cold low is the thermal low. A dry, sunny region becomes quite warm from intense surface heating thus generating a surface low pressure area The warm air is carried to high levels by convection, but cloudiness is scant because of lack of moisture. Since in 246
warm air, pressure decrease slowly with altitude, the warm surface low is not evident at upper levels. Unlike the cold low, the thennallow is relatively shallow with weak pressure gradients and no well defined cyclonic circulation. It generally supports good flying weather. However, during the heat of the day, one must be alert for high density altitude and convective turbulence. Wind Shear Line In some areas aloft, if wind shifts, a wind shear line is found in the shift border. By the time a
shear line is formed, wind direction and/or speed are virtually the same on both sides of the front. A shear line is also all that remains. These shear lines are zones of convergence creating forced upward motion. Consequently, considerable thunderstorm and rain shower activity occurs along a shear line.
VISIBILITY RESTRICTING PHENOMENA Most aircraft accidents related to low ceilings and visibilities involve pilots who are not instrument qualified. Fog is the most frequent causes of surface visibility blow 3 miles, and is one of the most common and persistent weather hazards encountered in aviation. Fog is a surface based cloud composed of either water droplets or ice crystals. Fog is classified by the way it forms. Radiation Fog
Radiation fog is relatively shallow fog. It may be dense enough to bide the entire sky or may conceal only part of the sky. "Ground fog" is a fonn of radiation fog. As viewed by a pilot in flight, dense radiation fog may obliterate the entire surface below him; a less dense fog may permit his observation of a small portion of the surface directly below him. Tall objects such as buildings, hills, and towers may protrude upward through ground fog giving the pilot fixed references for VFR flight. Radiation fog usually occurs in stable air associated with a high pressure system. Conditions favorable for radiation fog are clear sky, little or no wind, and small temperature-dew point spread (high relative humidity). These conditions produce the most frequent type of ground, or surface, based temperature inversion. The fog forms almost exclusively at night or near daybreak. Terrestrial radiation cools the ground; in turn, the cool ground cools the air in contact with it When the air is cooled to its dew point, fog forms. Radiation fog is restricted to land because water surfaces cool little from nighttime radiation. It is shallow when wind is calm. Wmds up to about 5 knots mix the air slightly and tend to deepen the fog by spreading the cooling through a deeper layer. Stronger winds disperse the fog or mix the air through a still deeper layer with stratus clouds forming at the top of the mixing layer. Ground fog usually "burns off" rather rapidly after sunrise. Other radiation fog generally clears before noon. Ifhigher clouds layers move over the fog, visibility will improve more slowly. Advection Fog
Advection fog forms when moist air moves over colder ground or water. It is most common along coastal areas but often develops deep in continental areas. At sea it is called "sea fog''. Advection fog deepens as wind speed increases up to about 15 knots. Wind much stronger than 15
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knots lifts the fog into a layer of low stratus or stratocumulus. The east coast of our country is quite vulnerable to advection fog. This fog frequently fonns offshore as a result of cold water and then is carried inland by the wind. Water areas in northern latitudes have frequent dense sea fog in summer as a result of warm, moist, tropical air flowing northward over colder lands. Advection fog is usually more extensive and much more persistent than radiation fog. Advection fog can move in rapidly regardless of the time of day or night.
Upslope Fog Upslope fog forms as a result of moist, stable air being cooled adiabatically as it moves up sloping terrain. Once the upslope wind ceases, the fog dissipates. Unlike radiation fog, it can form under cloudy skies. Upslope fog is common along the mountain. Upslope fog is often quite dense and extends to high altitudes.
Frontal Fog When relatively warm rain or drizzle falls through cool air, evaporation from the precipitation saturates the cool air and forms fog. Precipitation-induced fog can become quite dense and continue for an extended period of time. This fog may extend over large areas, completely suspending air operations. This fog can be very dense, and usually it does not clear until the rain moves out of the area It is most commonly associated with warm fronts, but can occur with slow moving cold fronts and with stationary fronts. Fog induced by frontal precipitation is in itself hazardous as any fog. It is especially critical, however, because it occurs in the proximity of precipitation and other possible hazards such as icing, turbulence, and thunderstonns.
Precipitation Precipitation occurs when cloud particles grow in size and weight until the atmosphere no longer can suspend them and they fall. Drizzle, rain, snow, ice pellets, hail, and ice crystals are the forms of precipitation which most commonly present ceiling and/or visibility problems. Drizzle or snow restricts visibility to a greater degree than rain. Drizzle falls in stable air and, therefore, often accompanies fog, haze, or smoke, frequently resulting in extremely poor visibility. ViSibility may be reduced to zero in heavy snow. Rain seldom reduces surface visibility below 1 mile except in brief: heavy showers, but rain does limit cockpit visibility. When rain streams over the aircraft windshield, freezes on it, or fogs over the inside surface, the pilots' visibility to the outside is greatly reduced.
low Stratus Clouds Stratus clouds, like fog, are composed of extremely small water droplets or ice crystals suspended in the air. An observer on a mountain in a stratus layer would call it fog. Stratus and fog frequently exist together. In many cases there is no real line of distinction between the fog and stratus; rather, one gradually merges into the other. Flight visibility may approach zero in stratus clouds. Stratus tends to be lowest during night and early morning, lifting or dissipating due to solar heating during the late morning or afternoon. Low stratus clouds often occur when moist air mixes with a colder air mass or in any situation where temperature-dew point spread is small. 248
Haze and Smoke Haze is a concentration of salt particles or other dry particles not readily classified as dust or other phenomenon. It occurs in stable air, is usually only a few thousand feet thick, but sometimes may extend as high as 15 000 feet. Haze layers often have defmite tops above which horizontal visibility is good. However, downward visibility from above a haze layer is poor, especially on a slant Visibility in haze varies greatly depending upon whether the pilot is facing the sun. Landing an aircraft into the sun is often hazardous ifhaze is present Smoke concentrations form primarily in industrial areas when air is stable. It is most prevalent at night or early morning under a temperature inversion but it can persist throughout the day. When skies are clear above haze or smoke, visibility generally improves during the day; however, the improvement is slower than the clearing of fog. Fog evaporates, but haze or smoke must be dispersed by movement of air. Haze or smoke may be blown away; or heating during the day may cause convective mixing spreading the smoke or haze to a higher altitude, decreasing the concentration near the surface. At night or early morning, radiation fog or stratus clouds often combine with haze or smoke. The fog and stratus may clear rather rapidly during the day but the haze and smoke will linger. A heavy cloud cover above haze or smoke may block sunlight preventing dissipation; visibility will improve little, if any, during the day. Low visibilities due to blowing dust or sand over semiarid or arid regions when winds are strong and the atmosphere is unstable. This is especially prevalent in spring in northern areas. If the dust extends upward to moderate or greater heights, it can be carried many miles beyond its source.
Blowing Restrictions to Visibility Strong wind lifts blowing dust in both stable and unstable air. When air is unstable, dust is lifted to great heights (as much as 15 000 feet) and may be spread over wide areas by upper winds. VISibility is restricted both at the surface and aloft. When air is stable, dust does not extend to as great a height as in unstable air and usually is not as widespread. Dust, once airborne, may remain suspended and restrict visibility for several hours after the wind subsides. Blowing sand is more local than blowing dust; the sand is seldom lifted above 50 feet. However, visibilities within it may be near zero. Blowing sand may occur in any dry area where loose sand is exposed to strong wind. Blowing snow can be troublesome. VISibility at ground level often will be near zero and the shy may become obscured when the particles are raised to great heights.
Vertical Visibility To be classified as obscuring phenomena, smoke, haze, fog, precipitation, or other visibility restricting phenomena must extend upward from the surface. When the sky is totally hidden by the surface based phenomena, the ceiling is the vertical visibility from the ground upward into the obscuration. An obscured ceiling differs from a cloud ceiling. With a cloud ceiling you normally can see the ground and runway once you descend below the cloud base. However, with an obscured ceiling, the obscuring phenomena restricts visibility between your altitude and the ground, and you 249
have restricted slant visibility. Thus, you cannot always clearly see the runway or approach light even after penetrating the level of the obscuration ceiling.
ARCTIC WEATHER The Arctic, strictly speaking, is the region which lies north of the Arctic Circles (66.5°latitude). Because of the lack of roads over most Arctic areas, aviation is the backbone of transportation between communities. As the economy expands, so will air transport.
Climate Climate of any region is largely detennined by the amount of energy received from the sun; but local characteristics of the area also influence climate. A large portion of the Arctic Ocean is covered throughout the year by a deep layer of ice- the permanent ice pack. Even through the ocean is ice-covered through much of the year, the ice and the water below contain more heat than the surrounding cold land, thus moderating the climate to some extent. Oceanic and coastal areas have a milder climate during winter than would be expected and a cool climate in summer. As opposed to large water bodies, large land areas show a more significant seasonal temperature variation.
Clouds and Precipiation Cloudiness over the Arctic is at a minimum during winter reaching a maximum in summer and fall. Spring also brings many cloudy days. During summer afternoons, scattered cumulus clouds forming over the interior occasionally grow into thundershowers. These thundershowers, usually circumnavigable, move generally from northeast to southwest in the polar easterlies which is opposite the general movement in midlatitudes. Precipitation in the Arctic is generally light. Annual amounts over the ice pack and along the coastal area are only 3 to 7 inches. The interior is somewhat wetter, with annual amounts of 5 to 15 inches. Precipitation falls mostly in the form of snow over ice caps and oceanic areas and mostly as summer rain over interior areas.
Wind Strong winds occur more often along the coasts than elsewhere. The frequency of high winds in coastal areas is greatest in fall and winter. Wmd speeds are generally light in the continental interior during the entire year, but are normally at their strongest during summer and fall.
Air Masses In winter, air masses form over the expanded ice pack and adjoining snow-covered land areas. These air masses are characterized by very cold surface air, very low humidity, and strong low-level temperature inversions. Occasionally, air from unfrozen ocean areas flows northward over the Arctic. These intrusions of moist, cold air account for most of the infrequent wintertime cloudiness and precipitation in the Arctic. During the summer, the top layer of the Arctic permafrost layer melts leaving very moist 250
ground, and the open water areas of the Polar Basin increase markedly. Thus, the entire area becomes more humid, relatively mild, and semimaritime in character. The largest amount of cloudiness and precipitation occurs inland during the summer months.
Fronts Occluded fronts are the rule. Weather conditions with occluded fronts are much the same in the Arctic as elsewhere-low clouds, precipitation, poor visibility, and sudden fog formation. Fronts are much more frequent over coastal areas than over the interior. Weather Hazards
Weather hazards include visibility restricting phenomena, blowing snow, icing, frost, and lack of contrast- whiteout.
Fog Fog limits landing and take-off in the Arctic more than any other visibility restriction. Water-droplet fog is the main hazard to aircraft operations in coastal areas during the summer. Ice fog is the major restriction in winter. Ice fog is common in the Arctic. It forms in moist air during extremely cold, calm conditions in winter, occurring often and tending to persist. Effective visibility is reduced much more in ice fog when one is looking toward the sun. Ice fog may be produced both naturally and artificially. Ice fog affecting aviation operations most frequently is produced by the combustion of aircraft fuel in cold air. When the wind is very light and the temperature is about -30~ or colder, ice fog often forms instantaneously in the exhaust gases of automobiles and aircraft. It lasts from as little as a few minutes to days. Steam fog, often called "sea smoke.., forms in winter when cold, dry air passes from land areas over comparatively warm ocean waters. Moisture evaporates rapidly from the water surface. But since the cold air can hold only a small amount of water vapor, condensation takes place just above the surface of the water and appears as "steam" rising from the ocean. This fog is composed entirely of water droplets that often freeze quickly and fall back into the water as ice particles. Low level turbulence can occur and icing can become hazardous. Advection fog, which may be composed either of water droplets or of ice crystals, is most common in winter and is often persistent Advection fog forms along coastal areas when comparatively warm, moist, oceanic air moves over cold land. If the land areas are hilly or mountainous, lifting of the air results in a combination of low stratus and fog. The stratus and fog quickly diminish inland. Lee sides of islands and mountains usually are free of advection fog because of drying due to compressional heating as the air descends downslope. Icing in advection fog is in the form of rime and may become quite severe.
Blowing Snow Over the frozen Arctic Ocean and along the coastal areas, blowing snow and strong winds are common hazards during autumn and winter. Blowing snow is a greater hazard to flying operations in the Artie than in midlatitudes because the snow is "dry" and fine and can be picked up easily by 251
light winds. Wmds in excess of 8 knots may raise the snow several feet off the ground obliterating objects such as runway markers. A sudden increase in surface wind may cause an unlimited visibility to drop to near zero in a few minutes. This sudden loss of visibility occurs frequently without warning in the Arctic. Stronger winds sometimes lift blowing snow to heights above 1 000 feet and produce drifts over 30 feet deep.
Icing Icing is most likely in spring and fall, but is also encountered in winter. During spring and fall, icing may extend to upper levels along frontal zones. While icing is mostly a problem over water and coastal areas, it does exist inland. It occurs typically as rime, but a combination of clear and rime is not unusual in coastal mountains. Frost In coastal areas during spring, fall, and winter, heavy frost and rime may form on aircraft parked outside, especially when fog or ice fog is present. This frost should be removed; it reduces
lift and is especially hazardous if surrounding terrain requires a rapid rate of climb.
White out "Whiteout.. is a visibility restricting phenomenon that occurs in the Arctic when a layer of cloudiness of uniform thickness overlies a snow or ice-covered surface. Parallel rays of the sun are broken up and diffused when passing through the cloud layer so that they strike the snow surface from many angles. The diffused light then reflects back and forth countless times between the snow and the cloud eliminating all shadows. The result is a loss of depth perception. Buildings, people, and dark colored objects appear to float in the air, and the horizon disappears. Low level flight over icecap terrain or landing on snow surfaces becomes dangerous. Disastrous accidents have occurred as a result of whiteouts. Arctic Flying Weather
Generally, flying conditions in the Arctic are good when averaged over the entire year; however, areas of Greenland compete with the Aleutians for the world's worst weather. These areas are exceptions. Whiteouts, in conjunction with overcast skies, often present a serious hazard especially for visual flight. Many mountain peaks are treeless and rounded rather than ragged, making them unusually difficult to distinguish under poor visibility conditions. Oceanic And Coastal Areas In oceanic and coastal areas, predominant hazards change with the seasons. In summer, the main hazard is fog in coastal areas. In winter, ice fog is the major restriction to aircraft operation. Blowing and drifting snow often restrict visibility also. Storms and well-defined frontal passages frequent the coastal areas accompanied by turbulence, especially in the coastal mountains. Icing is most frequent in spring and fall and may extend to high levels in active, turbulent frontal zones. Fog is also a source of icing when temperature is colder than freezing. 252
Continental Areas Over the continental interior, good flying weather prevails much of the year; although during winter, ice fog often restricts aircraft operations. In terms of ceiling and visibility, the summer months provide the best flying weather. However, the number of cloudy days during the summer exceeds those in winter. Thunderstorms develop on occasion during the summer, but they usually can be circumnavigated without much interference with flight plans.
TROPICAL WEATHER Technically, the Tropics lie between latitudes 23.SC'N and 23.SOS. However typical of this region sometimes extends as much as 45° from the equator. One may think of the Tropics as uniformly rainy, wann, and humid. The facts are, however, that the tropics contain both the wettest and driest regions of the world.
Circulation Wmd blowing out of the subtropical high pressure belts toward the equator form the northeast and southeast trade winds of the two hemispheres. These trade winds converge in the vicinity of the equator where air rises. This convergence zone is the "intertropical convergence zone" (ITCZ). In some areas of the world, seasonal temperature differences between land and water areas generate rather large circulation; these areas are "monsoon" regions.
Subtropical High Pressure Belts If the surface under the subtropical high pressure belts were all water of uniform temperature, the high pressure belts would be continuous highs around the globe. The belts would be areas of descending or subsiding air and would be characterized by strong temperature inversions and very little precipitation. However, land surfaces at the latitudes of the high pressure belts are generally wanner throughout the year than water surfaces. Thus, the high pressure anticyclones over oceans with troughs or lows over continents. The subtropical highs shift southward during the Northern Hemisphere winter and northward during summer. The seasonal shift, the height and strength of the inversion, and terrain features determine the weather in the subtropical high pressure belts.
The Intertropical Convergence Zone (ITCZ) Converging winds in the intertropical convergence zone (ITCZ) force air upward. The inversion typical of the subtropical high and trade wind belts disappears. Figures 8-7 shows the ITCZ and its seasonal shift. The ITCZ is well marked over tropical oceans but is weak and illdefined over large continental areas. Convection in the ITCZ carries huge quantities of moisture to great heights. Showers and thunderstorms frequent the ITCZ and tops to 40 000 feet or higher are common. Precipitation is copious. Since convection dominates the ITCZ. there is little difference in weather over island and open sea under the ITCZ. Flying through the ITCZ usually presents no great problem if one follows the usually practice of avoiding thunderstorms. He usually can find a safe corridor between storms. 253
( a)
( b)
Figure 8-7 ITCZ and Its Seasonal Shift. (a) in January; (b) in July
Tropical Cyclone Tropical cyclone is a generat term for nay low that originates over tropical oceans. Tropical cyclones are classified according to their intensity based on average one-minute wind speeds. Wmd gusts in these storms may be as much as SO percent higher than the average one-minute wind speeds. Tropical cyclone international classifications are: 1) Tropical Depression- highest sustained winds up to 34 knots (64 km/h), 2) Tropical Storm- highest sustained winds of35 through 64 knots (65 to 119 kmlh), and
3) Hurricane or 1)rphoon- highest sustained winds 65 knots (120 km/h) or more. Strong tropical cyclones are known by different names in different regions of the world. A tropical cyclone in the Atlantic and eastern Pacific is a "hurricane", in the western Pacific, "typhoon"; near Australia, and in the Indian
Ocean.
simply "cyclone". Regardless of the name,
these tropical cyclones produce serious aviation hazards. Movement Tropical cyclones in the Northern Hemisphere usually move in a direction between west and northwest while in low latitudes. As these storms move toward the midlatitudes, they come under the influence of the prevailing westerlies. At this time the storms are under the influence of two wind systems, i.e., the trade winds at low levels and prevailing westerlies aloft. Thus a storm may move very erratically and may even reverse course, or circle. Finally, the prevailing westerlies gain control and the storm recurves toward the north, then to the northeast, and finally to the east-northeast By this time the storm is well into midlatitudes. If the storm moves well inland, it loses its moisture source and weakens from starvation and increased surface friction, usually after leaving a trail of destruction and flooding. Typhoon originated in the western north Pacific often moves in three directions as showed in Figure 8-8: 1) the west, typhoon moves straight towards west from Philippine through the South Sea and tracks along the coast line of the China south sea, Hainan island and Vietnam; 2) the northwest, this track mainly affects the east areas such as Taiwan, Fujian, Jiang su or Zhejiang; 3) inverse track, typhoon moves toward northwest inland and then recurves to the northeast, affecting the east coast of China and the coast of Japan. 254
Figure 8-8 Typhoon Favored Directions of Movement
Teather in Tropical Stonns and Hurricanes While in its initial developing stage, the cyclone is characterized by a circular area of broken to ;)Vercast clouds in multiple layers. Embedded in these clouds are numerous showers and thunderstorms. Rain shower and thunderstorm coverage varies from scattered to almost solid. Diameter of the cloud pattern varies from less than 100 miles in small systems to well over 200 miles in large ones. As cyclonic flow increases, the thunderstorms and rain showers form into broken or solid lines paralleling the wind flow that is spiraling into the center of the storm. These lines are the spiral rain bands frequently seen on radar. These rain bands continually change as they rotate around the storm. Rainfall in the rain bands is very heavy, reducing ceiling and visibility to near zero. Wmds are usually very strong and gusty and, consequently, generate violent turbulence. Between the rain bands, ceilings and visibilities are somewhat better, and turbulence generally is less intense. The "eye" usually forms in the tropical storm stage and continues through the hurricane stage. In the eye, skies are free of turbulent cloudiness, and wind is comparatively light. The average diameter of the eye is between 15 and 20 miles, but sometimes is as small as 7 miles and rarely is more than 30 miles in diameter. Surrounding the eye is a wall of cloud that may extend above 50 000 feet This "wall cloud" contains deluging rain and the strongest winds of the storm. Maximum wind speeds of 175 knots have been recorded in some storms. Flying All pilots except those especially trained to explore tropical storms and hurricanes should avoid these dangerous storms. Occasionally, jet aircraft have been able to fly over small and less intense storms, but the experience of weather research aircraft show'" hazards at all levels within them. Tops of thunderstorms associated with tropical cyclones frequently exceed 50 000 feet. Wmds 255
in a typical hurricane are strongest at low levels, decreasing with altitude. However, research aircraft have frequently encountered winds in excess of 100 knots at 18 000 feet. Aircraft at low levels are exposed to sustained, pounding turbulence due to the surface friction of the fast-moving air. Turbulence increases in intensity in spiral rain bands and becomes most violent in the wall cloud surrO\mding the eye. An additional hazard encountered in hurricanes is erroneous altitude readings from pressure altimeters. These errors are caused by the large pressure difference between the periphery of the storm and its center. One research aircraft lost almost 2 000 feet true altitude traversing a storm while the pressure altimeter indicated a constant altitude of 5 000 feet.
In short, tropical cyclones are very hazardous, so avoid them! To bypass the storm in a minimum of time, fly to the right of the storm to take advantage of the tailwind. If you fly to the left of the storm, you will encounter strong headwinds which may exhaust your fuel supply before you reach a safe landing area.
SECTION 8
HAZARD WEATHEA
THUNDERSTORM Many times you have to make decisions involving thunderstorms and flying. Thunderstorms occur frequently in worm seasons. In general, thunderstorms are most frequent during July and August and least frequent in December and January. For a thunderstorm to form, three conditions are necessary: 1) an unstable lapse rate, 2) an initial lifting force, and 3) sufficient water vapor. The lifting force may be provided by several factors, such as sloping terrain, fronts, heating of the earth's surface, or any combination of these.
Life Cycle A thunderstorm cell during its life cycle progresses through three stages: 1) the cumulus, 2) the mature, and 3) the dissipating. It is virtually impossible to visually detect the transition from one stage to another; the transition is subtle and by no meads abrupt Furthermore, a thunderstorm may
be a cluster of cells in different stages of the life cycle. When warm, moist air is forced upward cooling to its dew point, water vapor condenses into small water droplets or ice crystals and a cumulus cloud forms. Although most cumulus clouds do not grow into thunderstorms, every thunderstorm begins as a cumulus. The key feature of the cumulus stage is an updraft as illustrated in Figure 8-9 (a). The updraft varies in strength and extends from very near the surface to the cloud top. Growth rate of the cloud may exceed 3 000 feet per minute, so it is inadvisable to attempt to climb over rapidly building cumulus clouds. Because of strong updrafts, precipitation usually does not fall. Instead, the water drops or ice crystals rise and fall within the cloud, growing larger with each cycle.
256
(a)
(b)
(c)
Figure 8-9 The Stages of a Thunderstorm
As the drops in the cloud grow too large to be supported by the updrafts, precipitation begins to fall. Precipitation beginning to fall from the cloud base is your signal that a downdraft has developed and a cell has entered the mature stage. Cold rain in the downdraft retards compressional heating, and the downdraft remains cooler than surrounding air. Therefore, its downdraft remains cooler than surrounding air. Its downward speed is accelerated and may exceed 2 500 feet per minute. The down rushing air spreads outward at the surface as shown in Figure 8-9 (b) producing strong, gusty surface winds, a sharp temperature drop, and a rapid rise in pressure. The leading edge of the surface wind is referred to as a "gust front". Meanwhile, updrafts reach a maximwn with speeds possibly exceeding 6 000 feet per minute. The adjacent updrafts and downdrafts cause severe turbulence. The most violent weather occurs during this phase of the life cycle. As the mature stage progresses, more and more air aloft is disturbed by the falling drops. Eventually, the downdrafts begin to spread out within the cell, taking the place of the weakening updrafts. Downdrafts characterize the dissipating stage of the thunderstorm cell as shown in Figure 8-9 (c) and the storm dies rapidly. When rain has ended and downdrafts have abated, the dissipating stage is complete. Individual thunderstorms measure from less than 5 miles to more than 30 miles in diameter. Cloud bases range from a few hundred feet in very moist climates to 10 000 feet or higher in drier regions. Tops generally range from 25 000 to 45 000 feet but occasionally extend above 65 000 feet.
Types ofThunderstorms Thunderstorms usually have similar physical features, but their intensity, degree of development, and associated weather do differ. They are generally classified as air mass thunderstorms or steady-state thunderstorms. Duration of the mature stage is closely related to severity of the thunderstorm. Some storms occur at random in unstable air, last for only an hour or two, and produce only moderate gusts and rainfall. These are the "air mass" type, but even they are 257
dangerously rough to fly through. Other thunderstorms form in lines, last for several hours, dump heavy rain and possibly hail, and produce strong, gusty winds and possibly tornadoes. These storms are the "steady state" type, usually are rougher than air mass storms, and virtually defy flight through them. A severe thunderstorm is one which has surface winds of 50 knots or more, and/or has hail3/4 inch or more in diameter. Air mass thunderstorms most often result from surface heating. Because the downdrafts in an air mass thunderstorm shut off the updrafts fairly quickly, this type of storm is self-destructive and relatively short-lived. Since air mass thunderstorms generally result from surface heating, they reach maximum intensity and frequency over land during middle and late afternoon. Off shore, they reach a maximum during late hours of darkness when land temperature is coolest and cool air flows off the land over the relatively warm water. Steady-state thunderstorms usually are associated with weather systems. Fronts, converging winds, and troughs aloft force upward motion spawning these storms. In a steady state storm cell, winds become markedly stronger with altitude, the upper portion of the cloud may be ''tilted", or blown downwind. In this case, precipitation falls through only a small portion of the rising air, or it may fall completely outside the cloud. As a result, precipitation falls outside the updraft as shown in Figure 8-10 allowing the updraft to continue unabated. Thus, the mature stage updrafts become stronger and last much longer than in air mass storms -hence, the name, "steady state". A steady state cell may Figure 8-10 Schematic of the Mature Stage of a persist for several hours and deliver the most Steady State Thunderstorm Cell violent thunderstorm hazards. The most violent type of steady-state thunderstorms are those generated by cold front or by squall lines. A squal~ line is a non-frontal, narrow band of active thunderstorms which normally contains very severe weather. Often it develops ahead of a fast moving cold front in moist, unstable air. A squall (SQ) means there has been a sudden increase in wind speed of at least 16 knots to a speed of 22 knots or more, and it lasted at least one minute. It often contains severe steady-state thunderstorms and presents the single most intense weather hazard to aircraft. It usually forms rapidly, generally reaching maximum intensity during the late afternoon and the first few hours of darkness. Hazards
Tornadoes Tornadoes occur with isolated thunderstonns at times, but much more frequently, they form with steady-state thunderstorms associated with cold fronts or squall lines. Reports or forecasts of tornadoes indicate that atmospheric conditions are favorable for violent turbulence. An aircraft 258
entering a tornado vortex is almost certain to suffer structural damage. Since the vortex extends well into the cloud,
any
pilot
inadvertently caught on instruments in a severe thunderstorm cloud encounter a bidden vortex. Frequently, cumulonimbus mamma clouds occur in connection with violent thunderstorms and tornadoes. The cloud displays rounded, irregular pockets or festoons from its base and is a signpost of violent turbulence. Figure
8~11
is a photograph of a cumulonimbus mamma
Figure 8-ll Cumulonimbus Mamma Clouds
cloud.
Turbulence Hazardous turbulence is present in all thunderstorms; and in a severe thunderstorm, it can damage an airframe. Strongest turbulence within the cloud occurs with shear between updrafts and downdrafts. Outside the cloud, shear turbulence has been encountered several thousand feet above and 20 miles laterally from a severe storm. A low level turbulent area is the shear zone between the plow wind and surrounding air. Often, a "roll cloud'' on the leading edge of a storm marks the eddies in this shear. The roll cloud is most prevalent with cold frontal or squall line thunderstorms and signifies an extremely turbulent zone. The first gust causes a rapid and sometimes drastic change in surface wind ahead of an approaching storm. Figure 8~12 shows a schematic cross section of a thunderstorm with areas outside the cloud
Figure 8~12 Schematic Cross Section of a Thunderstorm
where turbulence may be encountered. It is almost impossible to hold a constant altitude in a thunderstorm, and maneuvering in an attempt to do so greatly increases stresses on the aircraft. Stresses will be least if the aircraft is held
in a constant attitude and allowed to ''ride the waves". To date, we have no sure way to pick "soft spots" in a thunderstorm. Pressure usually falls rapidly with the approach of a thunderstorm, then rises sharply with onset of the first gust and arrival of the cold downdraft and heavy rain showers, falling back to normal as the storm moves on.
Icing Updrafts in a thunderstorm support abundant liquid water; and when carried above the freezing level, the water becomes supercooled. When temperature in the upward current cools to about 259
-15 ·c, much of the remaining water vapor sublimates as ice crystals; and above this level, the amount of supercooled water decreases. Supercooled water freezes on impact with an aircraft. Clear icing can occur at any altitude above the freezing level; but at high levels, icing may be rime or mixed rime and clear. The abundance of supercooled water makes clear very rapid between 0 ·c and -15 ·c, and encounters can be frequent in a cluster of cells. Thunderstorm icing can be extremely hazardous.
Hail Hail competes with turbulence as the greatest thunderstorm hazard to aircraft. Supercooled drops above the freezing level begin to freeze. Once a drop has frozen, other drops latch on and freeze to it, so the hailstone grows sometimes into a huge ice ball. Large hail occurs with severe thunderstorms usually built to great heights. Eventually the hailstones fall, possibly some distance from the storm core. Hail has been observed in clear air several miles from the parent thunderstorm. As hailstones fall through the melting level, they begin to melt, and precipitation may reach the ground as either hail or rain. Rain at the surface does not mean the absence of hail aloft. You should anticipate possible hail with any thunderstorm, especially beneath the anvil of a large cumulonimbus. Hailstones larger than one-half inch in diameter can significantly damage an aircraft in a few seconds. Low Ceiling and Visibility Visibility is generally near zero within a thunderstorm cloud. Ceiling and visibility also can become restricted in precipitation and dust between the cloud base and the ground. The restrictions create the same problem as all ceiling and visibility restrictions; but the hazards are increased many fold when associated with the other thunderstorm hazards of turbulence, hail, and lightning which make precision instrument flying virtually impossible. Thunderstorm Electricity Electricity generated by thunderstorms is rarely a great hazard to aircraft, but it may cause damage and is annoying to flight crews. Lightning is the most spectacular of the electrical discharges. A lightning strike can puncture the skin of an aircraft and can damage communication and electronic navigational equipment. Lightning has been suspected of igniting fuel vapors causing explosion; however, serious accidents due to lightning strikes are extremely rare. Nearby lightning can blind the pilot rendering by instrument or by visual reference. Nearby lightning can also induce permanent errors in the magnetic compass. Lightning discharges, even distant ones, can disrupt radio communications on low and medium frequencies. A few pointers on lightning: 1) The more frequent the lightning, the more severe the thunderstorm; 2) Increasing frequency of lightning indicates a growing thunderstorm; 3) Decreasing lightning indicates a storm nearing the dissipating stage; 4) At night, frequent distant flashes playing along a large sector of the horizon suggest a probable squall line. Even though thunderstorms are cumulus clouds formed in unstable air they can sometimes penetrate overlying bands of stratiform clouds. A layer of stratiform clouds may sometimes form in a mildly stable layer while a few convective clouds penetrate the layer, thus merging stratiform with
260
cumuliform. Under the right conditions, the cumuliform clouds can become thunderstorms which are completely obscured by the surrounding stratus. These are known as "embedded thunderstorms". Because these thunderstorms are obscured by other clouds and it is impossible for a pilot to visually detour around them. they present a particular hazard to IFR flight
Thunderstorms and Radar Weather radar detects droplets of precipitation size. Strength of the radar return (echo) depends on drop size and number. The greater the number of drops, the stronger is the echo; and the larger the drops, the stronger is the echo. Drop size determines echo intensity to a much greater extent than does drop number. Meteorologists have shown that drop size is almost directly proportional to rainfall rate; and the greatest rainfall rate is in thunderstorms. Therefore, the strongest echoes are thunderstorms. Hailstones usually are covered with a film of water and, therefore, act as huge water droplets giving the strongest of all echoes. Showers show less intense echoes; and gentle rain and snow return the weakest of all echoes. Since the strongest echoes identify thunderstorms, they also mark the areas of greatest hazards. Radar information can be valuable both from ground based radar for preflight planning and from airborne radar for severe weather avoidance. Thunderstorms build and dissipate rapidly, and they also may move rapidly. Therefore, do not attempt to preflight plan a course between echoes. The best use of ground radar information is to isolate general areas and coverage of echoes. You must evade individual storms from in flight observations either by visual sighting or by airborne radar. Whether to fly into an area of radar echoes depends on echo intensity, spacing between the echoes, and the capabilities of your aircraft. Remember that weather radar detects only precipitation drops; it does not detect minute cloud droplets. Therefore, the radar scope provides no assurance of avoiding instrument weather in clouds and fog. The most intense echoes are severe thunderstorms. Remember that bail may fall several miles from the cloud, and hazardous turbulence may extend as much as 20 miles from the cloud. Avoid the most intense echoes by at least 20 miles; that is, echoes should be separated by at least 40 miles before you fly between them. As echoes diminish in intensity, you can reduce the distance by which you avoid them. Figure 8-13 Figure 8-13 Use of Airborn rada to Avoid Heavy illustrates use of airborne radar in avoiding Precipitation and Thrbulence thunderstorms.
Do's and Don't of Thunderstorm Flying Remember this: never regard any thunderstorm as "light" even when radar observers report the 261
echoes are of light intensity. Avoiding thunderstorms is the best policy. Following are some Do's and Don'ts of thunderstorm avoidance: A. Don't land or take off in the face of an approaching thunderstorm. A sudden wind shift or low level turbulence could cause loss of control. B. Don't try to circumnavigate thunderstorms covering 6/10 of an area or more either visually or by airborne radar. C. Do avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus. D. Do clear the top of a known or suspected severe thunderstorm by at least 1 000 feet altitude for each 10 knots of wind speed at the cloud top. This would exceed the altitude capability of most aircraft. E. Do remember that vivid and frequent lightning indicates a severe thunderstorm., F. Do regard as severe any thunderstorm with tops 35 000 feet or higher whether the top is visually sighted or determined by radar. A special condition need to be noticed is that a clear area in a line of thunderstorm echoes on a radar scope indicates an area where precipitation drops are not detected, but is not a safe area, it usually be the rapid updraft part of thunderstorms.
WIND SHEAR Wmd shear generates eddies between two wind currents of differing velocities. The differences may be in wind speed, wind direction, or in both. Wind shear may be associated with either a wind shift or a wind speed gradient at any level in the atmosphere. It can subject your aircraft to sudden updrafts, downdrafts, or extreme horizontal wind components, causing loss of lift or violent changes in vertical speeds or altitudes. Often, there is little or no turbulence associated with wind shear. Wind Shear Dangerous In a situation where is a sudden increase in headwind (or decrease in tailwind) the aircraft's
momentum keeps it moving through space at the same ground speed as before. This means that the aircraft will be moving through the air faster than before and there will be an increase in its indicated airspeed. The aircraft will react to this increase by pitching up and by tending to climb (or descend more slowly). The same is when a tailwind shears to calm or a headwind. When there is a sudden increase in a tailwind (or decrease in the headwind), just the opposite occurs. In these conditions, the aircraft tends to lose airspeed, get low, and pitch nose down. The aircraft will require more power and a higher pitch attitude to stay on glide slope. The same is when a headwind shears to calm or a tailwind. Responding promptly by adding power and pitching up, a pilot may overshoot the glide slope and airspeed target but then recover. The more rapid shift in wind speed or direction the more noticeable change in the aircraft's indicated airspeed. Severe wind shear is defined as a rapid change in wind direction or velocity causing airspeed changes greater than 15 knots or vertical
262
~eed
changes greater than 500 feet per minute.
_on ditions Generating Low Level Wind Shear
When wind shear occurs below 500 feet high, we call it Low-Level wind shear. Four common ;e!1erators of this wind shear conditions are thunderstonns, frontal systems, temperature inversion 1::d surface friction.
lind Shear and Thunderstorms The shear from thunderstonns usually occurs between updrafts and downdrafts. Outside the doud, shear has been encountered several thousand feet above and 20 miles laterally from a severe storm. A low level shear is the zone between the plow wind and the surrounding air. Wind shear can be encountered on all sides and in the downdraft directly under the thunderstorm cell, as showed in Figure 8-14. The shear is usually encountered close to the ground where there is little time or altitude to recover. The magnitude of the shear is often very severe, especially in situations involving microbursts.
Wmd shear area Gust front
Figure 8-14 Wind Shear with a Thunderstorm
A microburst is an intense, localized downdraft which spreads out in all direction when it reaches the surface. Any convective cloud can produce this phenomenon. This includes rains showers, virga and thunderstorms. A microburst is a very narrow downdraft of very high speed wind, it typically covers less than two and a half miles at the surface, with vertical speeds up to 6 000 feet per minute. A microburst creates severe horizontal and vertical wind shears which pose serious hazards to aircraft, particularly those near the surface. When the downdraft approaches the surface, the wind flows outward from the core in all directions. Not only are these outflow winds very strong(up to 45 knots)but their effect is doubled when an aircraft flies through the shear. For example, a 45 knot headwind approaching the microburst will be a 45 knot tailwind flying out the other side-a change of 90 knots. This is usually a short-lived phenomena, seldom lasting more than 15 minutes from the time the burst strikes the ground until it dissipates.
An aircraft approaching a microburst (as shown in Figure 8-15) will first experience an 263
increasing headwind as it encounters the outflow. The increasing headwind shear causes the indicated airspeed to increase and gives the aircraft a tendency to pitch up and climb. This increase in performance without an increase in power might induce an unwary pilot into reducing power to maintain airspeed and flight path. As the aircraft flies into the core of the microburst. the headwind shifts to a downdraft. The sudden loss of headwind will cause indicated airspeed to drop and cause the aircraft to pitch down and descend. The strong downdraft increases the tendency to descend and the aircraft can quickly get into the situation of having low air speed and a very high rate of descent. As the aircraft flies out the backside of the microburst, it encounters an increasing tailwind shear that further reduces indicated airspeed and performance.
'
_ ..
'' '
oarfJo-.r
Figure 8-15 Approaching a Mic:robunt
Although microbursts are commonly associated with heavy precipitation in thunderstorms, they often are associated with virga, or streamers of precipitation that trail beneath a cloud but which evaporate before they reach the ground. If there is no precipitation, your only cue may be a ring of dust at the surface. Wind Shear in a Frontal Zone
As you have learned before, a front can contain many hazards. However, a front can be between two dry stable airmasses and can be devoid of clouds. Even so, wind changes abruptly in the frontal zone and can induce wind shear. The degree of wind shear depends on the velocity of the front moving and the temperature variation cross the front. Normally, the more velocity (more than 55 km/h) and/or the more temperature variation (more than 5 "C), the wind shear is more serious. Wind Shear with a Low-level Temperature Inversion
A temperature inversion forms near the surface on a clear night with calm or light surface wind. Wmdjust above the inversion may be relatively strong. As illustrated in Figure 8-16, a wind shear zone develops between the calm and the stronger winds above. Eddies in the shear zone cause 264
airspeed fluctuations as an aircraft climbs or descends through the inversion. An aircraft most likely is either climbing from strong wind take-off or approaching to land when passing through the inversion; therefore, airspeed is slow- only a few knots greater than stall precariously close to the ground. When taking off or landing in calm wind under clear skies within a few hours before or after sunrise, be prepared for a temperature inversion near the Figure 8-16 Wind Shear in a Zone between an ground. A shear zone in the inversion is Inversion Layer relatively certain if the wind at 2 000 to 4 000 is 25 knots or more. Since surface wind is calm or very light, take-off or landing can be in any direction. Take-off may be in the direction of the wirtd above the inversion. If so, the aircraft encounters a sudden tailwind and a corresponding loss of airspeed when climbing through the inversion. Stall is possible. If the approach is into the wind above the inversion, the headwind is suddenly lost when descending through the inversion. Again, a sudden loss in airspeed may induces stall. When taking off or landing in calm win~ JDder clear skies within a few hours before or after sunrise, be prepared for a temperature. Surface friction
Rubbing two objects against each other creates friction. If the objects are fluid currents, friction creates eddies along a common shallow mixing zone, and a mass transfer takes place in the shallow mixing layer. This zone of induced eddies and mixing is a shear zone. The rougher the terrain. the greater is the frictional effect, so the heavier the wind shear. Wind Shear Detecting Experiment
There are several kinds of wind shear detecting experiment, such as Doppler radar units. Mary airports have the less sophisticated Low-Level Wmd Shear Alert System (LLWAS), which is used to alert pilots to the possibility of wind shear on or near the airport. This system consists of wind sensors located around the perimeter ofthe airport as well as a center field wind sensor. When there is a significant difference in speed or direction between any of these sensors and the center field sensor, the tower will broadcast the difference. There are some wind shear conditions that exceed the performance capability of typical air carrier aircraft. For this reason it is imperative that pilots avoid situations whert severe wind shear is either reported or is likely to exist The greatest danger from a wind shear encountered at low altitude is that the aircraft will pick up such a high rate of descent that the pilots will be unable to stop it before hitting the ground. The technique to be used during a wind shear encounter essentially involves trading airspeed for altitude. The exact procedures vary from one aircraft to another but if 265
an aircraft encounters severe wind shear, the pilot should maintain or increase the pitch attitude, increase power to the maximum available and accept lower than normal airspeed indications. If this does not arrest the descent, the pilot should continue to pitch up until the descent does stop or until "stick shaker'' is encountered.
FROST AND ICE Aircraft icing is one of the major weather hazards to aviation. Icing is a cumulative hazard. It reduces aircraft efficiency by increasing weight, reducing life force, decreasing thrust, and increasing drag. Aircraft with ice, snow, or frost on the wings may experience increased stall speed, decreased angle of attack for stalls, and increased pitch up tendencies. Test data indicate that ice, snow, or frost formations having a thickness and surface roughness similar to medium or coarse sandpaper on the leading edge and upper surface of a wing can reduce wing lift by as much as 30 percent and increase drag by 40 percent. Icing also seriously impairs aircraft engine performances. Other icing effects include false indications on flight instruments, loss of radio communications, and loss of operation of control surfaces, brakes, and landing gear.
Structural Icing Two conditions are necessary for structural icing in flight: 1) the aircraft must be flying through visible water such as rain or cloud droplets, and 2) the temperature of the aircraft surface is O"C or colder. In those conditions, the water droplets become "supercooled". It is the supercooled water that increases the rate of icing and is essential to rapid accretion. Although their temperature is below freezing, they remain in a liquid state. Supercooled water is in an unstable liquid state; when such an unstable water droplet strikes an exposed object, it freezes on impact. The types of structural icing are clear, rime, and a mixture of the two. Each type has its identifying features. Clear ice forms when drops are large as in freezing rain or in cumuliform clouds. When the droplets flow over the aircraft structure and slowly freeze, they can glaze the aircraft's surfaces. Clear ice is the most serious ofthe various forms of ice because it adheres tenaciously to the aircraft and is more difficult to remove than rime ice. Rime ice forms when drops are small, such as those in stratified clouds or light drizzle. It has an opaque appearance caused by air being trapped in the water droplets as they freeze instantly. Rime ice is lighter in weight than clear ice and its weight is of little significance. However, its irregular shape and rough surface make it very effective in decreasing aerodynamic efficiency of airfoils, thus reducing lift and increasing drag. Rime ice is brittle and more easily removed than clear ice. Mixed ice forms when drops vary in size or when liquid drops are intermingled with snow or ice particles. It can form rapidly. Ice particles become imbedded in clear ice, building a very rough accumulation sometimes in a mushroom shape on leading edges. A condition favorable for rapid accumulation of clear icing is freezing rain below a frontal surface. Freezing rain always occurs in a temperature inversion. Rain forms above the frontal surface at temperatures wanner than freezing. Subsequently, it falls through air at temperatures
266
below freezing and becomes supercooled. Eventually, the water drops will freeze into ice pellets. So any encounter with ice pellets in flight indicates that there is freezing rain at a higher altitude. The supercooled drops freeze on impact with an aircraft surface. The icing can be critical because of the large amount of supercooled water. Snow always forms in colder than freezing temperatures by the progress of sublimation. This is when water goes straight from its vapor state into ice without ever being a liquid. When the snow fall to altitudes with above freezing temperatures, it will begin to melt, become wet snow and eventually tum into rain. Frost is a hazard to flying long recognized in the aviation community. Experienced pilots have learned to remove all frost from airfoils prior to take-off. It interferes with smooth airflow over the wings and can cause early airflow separation, resulting in a loss of lift. Frost forms when both the temperature and the dew point of the collecting surface are below freezing. When this occurs, water vapor sublimates directly into frost. Frost often forms near the surface primarily in clear, stable air and with light winds, this condition most occurs on clear nights with little or no wind conditions which in all other respects make weather ideal for flying. Because of this, the real hazard is often minimized. Frost also can form in flight when a cold-soaked aircraft descends into warm, moist air. In this condition, it is easy removed by the blowing wind. This type of frost presents no hazard to flight
Induction System Icing Ice frequently forms in the air intake of an engine robbing the engine of air to support combustion. This type icing occurs with both piston and jet engines, and almost everyone in the aviation community is familiar with carburetor icing. The downward moving piston in a piston engine or the compressor in a jet engine forms a partial vacuum in the intake. Adiabatic expansion in the partial vacuum cools the air. Ice forms when the temperature drops below freezing and sufficient moisture is present for sublimation. In piston engines, fuel evaporation produces additional cooling. Induction icing always lowers engine performance and can even reduce intake flow below that necessary for the engine to operate. Induction icing potential varies greatly among different aircraft and occurs under a wide range of meteorological conditions. It is primarily an engineering and operating problem rather than meteorological. Icing of the pitot tube reduces ram air pressure on the airspeed indicator and renders the instrument unreliable. Most modem aircraft also have an outside static pressure port as part of the pitot-static system. Icing of the static pressure port reduces reliability of all instruments on the system-the airspeed. rate-of-climb, and the altimeter. Ice forming on the radio antenna distorts its shape, increases drag, and imposes vibrations that may result in failure in the communications system of the aircraft. The severity of this icing depends upon the shape, location, and orientation of the antenna.
Icing and Cloud Types Basically, all clouds at subfreezing temperatures have icing potential. However, drop size, drop 267
distribution, and aerodynamic effects of the aircraft influence ice formation. Ice may not form even though the potential exists. The condition most favorable for very hazardous icing is the presence of many large, supercooled water drops. Conversely, an equal or lesser number of smaller droplets favors a slower rate of icing. Small water droplets occur most often in fog and low-level clouds. Drizzle or very light rain is evidence of the presence of small drops in such clouds; but in many cases there is no precipitation at all The most common type of icing found in lower-level stratus clouds is rime. On the other band, thick extensive stratified clouds that produce continuous rain such as altostratus and nimbostratus usually have an abundance of liquid water because of the relatively larger drop size and number. Such cloud systems in winter may cover thousands of square miles and present very serious icing conditions for protracted flights. Particularly in thick clouds, concentrations of liquid water normally are greater with warmer temperatures. Thus, heaviest icing usually will be found at or slight above the freezing level where temperature is never more than a few degrees below freezing. In layer type clouds, continuous icing conditions are rarely found to be more than 5 000 feet above the freezing level, and usually are two or three thousand feet thick. The upward currents in cumuliform clouds are favorable for the formation and support of many large water drops. The size of raindrops and rainfall intensity normally experienced from showers and thunderstorms confmn this. When an aircraft enters the heavy water concentrations found in cumuliform clouds, the large drops break and spread rapidly over the leading edge of the airfoil forming a film of water. If temperatures are freezing or colder, the water freezes quickly to form a solid sheet of clear ice. Pilots usually avoid cumuliform clouds when possible. Consequently, icing reports from such clouds are rare and do not indicate the frequency with which it can occur. The updrafts in cumuliform clouds carry large amounts of liquid water far above the freezing level. On rare occasions icing has been encountered in thunderstorm clouds at altitudes of 30 000 to 40 000 feet where the free air temperature was colder than minus 40
·c.
While an uvper limit of critical icing potential cannot be specified in cumuliforrn clouds, the cellular distribution of such clouds usually limits the horizontal extent of icing conditions. An exception, of course, may be found in a protracted flight through a broad zone of thunderstorms or heavy showers.
Other Factors in Icing A condition favorable for rapid accumulation of clear icing is freezing rain below a frontal surface. Rain forms above the frontal surface at temperatures warmer than freezing. Subsequently, it falls through air at temperatures below freezing and becomes supercooled. The supercooled drops freeze on impact with an aircraft surface. It may occur with either a warm front or a cold front. The icing can be critical because of the large amount of supercooled water. Icing can also become serious in cumulonimbus clouds along a surface cold front, along a squall line, or embedded in the cloud shield of a warm front. Air blowing upslope is cooled adiabatically. When the air is cooled below the freezing point, 268
the water becomes supercooled. In stable air blowing up a gradual slop, the cloud drops generally remain comparatively small since larger drops fall out as rain. Ice accumulation is rather slow and you should have ample time to get out of it before the accumulation becomes extremely dangerous. When air is unstable, convective clouds develop a more serious hazard. Icing is more probable and more hazardous in mountainous regions than over other areas. Mountain ranges cause rapid upward air motions on the windward side, and these vertical currents support large water drops. The movement of a frontal system across a mountain range often combines the normal frontal lift with the upslope effect of the mountains to create extremely hazardous icing zones. Each mountainous region has preferred areas of icing depending upon the orientation of mountain ranges to the wind flow. The most dangerous icing takes place above the crests and to the windward side of the ridges. This zone usually extends about 5 000 feet above the tops of the mountains; but when clouds are cumuliform, the zone may extend much higher. Icing may occur during any season of the year; but in temperate climates icing is more frequent in winter. The freezing level is nearer the ground in winter than in summer leaving a smaller low-level layer of airspace free of icing conditions. Cyclonic storms also are more frequent in winter, and the resulting cloud systems are more extensive. Polar regions have the most dangerous icing conditions in spring and fall. During the winter the air is normally too cold in the polar regions to contain heavy concentrations of moisture necessary for icing, and most cloud systems are stratiform and are composed of ice crystals.
Points for Icing No person may dispatch or release an aircraft, continue to operate en route, or land when in the opinion of the pilot-in-command or aircraft dispatcher, icing conditions are expected or met that might adversely affect the safety of the flight No person may take off when frost, snow or ice is adhering to the wings, control surfaces or propellers of the aircraft. A pre-take-off inspection for ice, snow, or frost must be completed no more than 5 minutes prior to take-off anytime conditions require it. Using deicing or anti-icing equipment when accumulations of ice are not too great. When such equipment becomes less than totally effective, change course or altitude to get out of the icing as rapidly as possible. In stratiform clouds, you can likely alleviate icing by changing to a flight level and above-freezing temperatures or to one colder than - to·c. An altitude change also may take you out of clouds. Rime icing in stratiform clouds can be very extensive horizontally. In frontal freezing rain, you may be able to climb or descend to a layer warmer than freezing. Temperature is always wanner than freezing at some higher altitude. If you are going to climb, move quickly; procrastination may leave you with too much ice. If you are going to descend, you must know the temperature and terrain below. Avoid cumuliform clouds if at all possible. Clear ice may be encountered anywhere above the freezing level. Most rapid accumulations are usually at temperatures from o•cto - 15•c . Avoid abrupt maneuvers when your aircraft is heavily coated with ice since the aircraft has lost some of its aerodynamic efficiency. When "iced up", fly your landing approach with power.
269
TURBULENCE Everyone who flies can encounter turbulence at some time or other. A turbulent atmosphere is one in which air currents vary greatly over short distances. As an aircraft moves through these currents, it undergoes changing accelerations that jostle it from its smooth flight path. Knowing where to expect turbulence helps a pilot avoid or minimize turbulence discomfort and hazards. The main causes of turbulence are 1) convective currents, 2) obstructions to wind flow, and 3) wind shear. Turbulence also occurs in the wake ofmoving aircraft whenever the airfoils exert life -wake turbulence. Convective Currents
Convective currents are a common cause of turbulence, especially at low altitudes. These currents are localized vertical air movements, both ascending and descending. Convective currents are most active on warm summer afternoons when winds are light. Heated air at the surface creates a shallow, unstable layer, and the warm air is forced upward. Convection increases in strength and to greater heights as surface heating increases. Barren surfaces such as sandy or rocky wastelands and plowed fields become hotter than open water or ground covered by vegetation. Thus, air at and near the surface heats unevenly. Because of uneven heating, the strength of convective currents can vary considerably within short distances. When cold air moves over a warm surface, it becomes unstable in lower levels. Convective currents extend several thousand feet above the surface resulting in rough. choppy turbulence when flying in the cold air. This condition often occurs in any season after the passage of a cold front. Figure 8-17 illustrates the effect of low-level convective turbulence on aircraft. Turbulence on approach can cause abrupt changes in airspeed and may even result in a stall at a dangerously low altitude. To prevent the danger, increase airspeed slight over normal approach speed. This procedure may appear to conflict with the rule of reducing airspeed for turbulence penetration; but remember, the approach speed for your aircraft is well below the recommended turbulence penetration speed.
Figure 8-17 Effect of Convective Currents.
270
As air moves upward, it cools by expansion. A convective current continues upward until it reaches a level where its temperature cools to the same as that of the surrounding air. If it cools to saturation, a cloud forms. Billowy fair weather cumulus clouds, usually seen on sunny afternoons, are signposts in the sky indicating convective turbulence. The cloud top usually marks the approximate upper limit of the convective current. A pilot can expect to encounter turbulence beneath or in the clouds, while above the clouds, air generally is smooth. You will find most comfortable flight above the cumulus.
Obstructions to Wind Flow Obstructions such as buildings, tree, and rough terrain disrupt smooth wind flow into a complex snarl of eddies as diagrammed in Figure 8-18. An aircraft flying through these eddies experiences turbulence. This turbulence we classify as "mechanical" since it results from mechanical disruption of the ambient wind flow.
~-----~----------
Figure 8-18 Eddy Currents Formed by Wind Blowing over Obstructions
The degree of mechanical turbulence depends on wind speed and roughness of the obstructions. The higher the speed and/or the rougher the surface, the greater is the turbulence. The wind carries the turbulent eddies downstream-how far depends on wind speed and stability of the air. Unstable air allows larger eddies to form than those that form in stable air; but the instability breaks up the eddies quickly, while in stable air they dissipate slowly. The airport area is especially vulnerable to mechanical turbulence which invariably causes
gusty surface winds. When an aircraft is in a low-level approach or a climb, airspeed fluctuates in the gusts, and the aircraft may even stall. During extremely gusty conditions, maintain a margin of airspeed above normal approach or climb speed to allow for changes in airspeed. When landing with a gusty crosswind, be alert for mechanical turbulence and control problems caused by airport structures upwind. Surface gusts also create taxi problems. Mechanical turbulence can affect low-level cross-country flight about anywhere. Mountains can generate turbulence to altitudes much higher than the mountains themselves.
Mountain Wave When stable air crosses a mountain barrier, air flowing up the windward side is relatively 271
smooth. Wmd flow across the barrier is laminar- that is, it trends to flow in layers. The barrier may set up waves in these layers much as waves develop on a disturbed water surface as showered in Figure 8-19. The wave pattern may extend 100 miles or more downwind from the barrier. Wave crests extend well above the highest mountains, sometimes into the lower stratosphere. Under each wave crest is a rotary circulation. The "prove" forms below the elevation of the mountain peaks. Turbulence can be violent in the overturning rotor. Updrafts and downdrafts in the waves can also create violent turbulence. When moisture is sufficient to produce clouds on the windward side, they are stratified. Crests of the standing waves may be marked by stationary, lens-shaped clouds known as "standing lenticular clouds". These clouds form in the updrafts and dissipate in the downdrafts so they do not move as the wind blows tbrough them. The rotor may also be marked by a ''rotor, cloud, lower than the lenticular clouds. But remember, clouds are not always present to mark the mountain wave. Sometimes, the air is too dry. Always anticipate possible mountain wave turbulence when strong winds of 40 knots or greater blow across a mountain or ridge and the air is stable.
Figure 8-19 Schematic Cross Section of a Mountain Wave
Frontal Zone
Fronts often have turbulence due the wind shift associated with a sharp pressure trough. Wtnd changes abruptly in the frontal zone and can induce wind shear turbulence. The degree of turbulence depends on the magnitude of the wind shear. More frequently you will encounter turbulence in the colder air mass side than the warmer side. When turbulence is expected in a frontal zone, follow turbulence penetration procedures recommended in your aircraft manual, try to cross the front at right angles to minimize the time you are exposed to this turbulence. The Jet Stream
The jet stream is a narrow, shallow, meandering river of maximum winds extending around the globe in a wavelike pattern. There may be two or more jet streams in existence at one time. The jet stream typically occurs in a break in the tropopause. Therefore, a jet stream occurs in an area of intensified temperature gradients characteristic of the break. The concentrated winds, by arbitrary definition, must be 50 knots or greater to classify as a jet stream. The jet maximum is not constant; 272
rather, it is broken into segments, shaped something like a boomerang. Jet stream segments move with pressure ridges and troughs in the upper atmosphere. In general they travel faster than pressure systems, and maximum wind speed varies as the segments progress through the systems. In midlatitude, wind speed in the jet stream averages considerably stronger in winter than in summer. The highest wind speeds can be found on the polar side of the jet core. Also the jet shifts farther south in winter than in summer. Wmd speed decreases outward from the jet core. The rate of decrease of wind speed is considerably greater on the polar side than on the equatorial side; hence, the magnitude of wind shear is greater on the polar side than on the equatorial side. Strong, long-trajectory jet streams usually are associated with well-developed surface lows and frontal systems beneath deep upper troughs or lows. Generally speaking, the jet stream will lie to the north of the surface position of a front. Cyclogenesis is usually south of the jet stream and moves nearer as the low deepens. If an occluded front forms, the jet stream will often crosse the frontal system near the point of occlusion. Air travels in a "corkscrew" path around the jet core with upward motion on the equatorial side. Therefore, when high-level moisture is present, cirriform clouds form on the equatorial side of the jet Jet stream cloudiness can form independently of well-defined pressure systems. Such cloudiness ranges primarily from scattered to broken coverage in shallow layers or streaks. Their sometimes fishhook and streamlined, wind-swept appearance always indicates very strong upper wind usually quite far from developing or intense weather systems. Figure 8-20 is a satellite photograph showing a cirrus band.
Figure 8-20 Infrared Photograph of the Jet Stream
A more important aspect of the jet stream cirrus shield is its association with turbulence. Extensive cirrus cloudiness often occurs with deepening surface and upper lows; and these deepening systems produce the greatest turbulence.
Clear Air Turbulence High altitude turbulence (normally above 15 000 feet MSL) not associated with cumuliform cloudiness should be reported as CAT. Clear air turbulence (CAT) implies turbulence devoid of 273
clouds. However, we commonly reserve the term for high level wind shear turbulence, even when in cirrus clouds. The jet stream is a common source of CAT. Cold outbreaks colliding with warm air from the south intensify weather systems in the vicinity of the jet stream along the boundary between the cold and warm air. CAT develops in the turbulent energy exchange between the contrasting air masses. Cold and warm advection along with strong wind shears develop near the jet stream, especially where curvature of the jet stream sharply increases in deepening upper troughs. CAT is most pronounced in winter when temperature contrast is greatest between cold and warm air. A preferred location of CAT is in an upper trough on the cold (polar) side of the jet stream. Another frequent CAT location is along the jet stream north and northeast of a rapidly deepening surface low, as showed in Figure 8-21. The strongest turbulence will be found on the polar side of a curving jet stream associated with upper trough.
~
jet stream
~
~~~ CAT
_
~
-----
~"\ Figure 8-21
A Frequent CAT Location Is along the Jet Stream North and Northeast of a Rapidly Deepening Surface Low
If you encounter turbulence in the jet stream and you have a direct headwind or tailwind you should change course or altitude since these turbulent areas are elongated with the wind, and are shallow and narrow. With the wind parallel to your heading, you are likely to remain in the jet and the turbulence for a considerable distance. If you approach a jet stream from the polar side the temperature will drop. When you approach it from the tropical side, the temperature rises. If you want to traverse an area of CAT more quickly, watch the temperature gauge for a minute or two. If the temperature is rising- clime; if the temperature is falling- descend. Application of these rules will prevent you from following the sloping tropopause and staying in the turbulent If the temperature remains constant, the flight is probably close to the level of the core, so either climb or descend as is convenient Recall that there is a downdraft on the polar side and an updraft on the tropical side. Even in the absence of a well-defined jet stream, CAT often is experienced in wind shears associated with sharply curved contours of strong lows, troughs, and ridges aloft, and in areas of strong, cold or warm air advection. If turbulence is encountered in an abrupt wind shift associated with a sharp pressure trough, establish a course across the trough rather than parallel to it. A change
274
in flight level is not likely to alleviate the bumpiness.
Intensity of Turbulence You are encouraged to report encounters with turbulence, including the frequency and intensity. Turbulence is considered to be "occasional" when it occurs less than one· third of a given time span. "Intermittent'' when it covers one·third to tw~thirds of the time. Turbulence that occurs more than 2/3 of the time is continuous. You can classify the intensity using the following guidelines: Light- Slight erratic changes in altitude or attitude; slight strain against seat belts. Light chop is slight, rapid bumpiness without appreciable changes in altitude or attitude. Moderate- Changes in altitude or attitude occur, but aircraft remains in positive control at all times; usually changes in indicated airspeed; definite strains against seat belt. Moderate chop is rapid bumps or jolts without appreciable changes in altitude or attitude. Severe -Abrupt changes in altitude or attitude; usually large variations in indicated airspeed; aircraft may be momentarily out of control; occupants forced violently against seat belts. Extreme-Aircraft practically impossible to control; may cause structural damage. Aircraft reaction to turbulence varies with the difference in wind speed in adjacent currents, size of the aircraft, wing loading, airspeed, and aircraft attitude. When an aircraft travels rapidly from one current to another, it undergoes abrupt changes in acceleration. Obviously, if the aircraft moved more slowly, the changes in acceleration would be more gradual. The first rule in flying turbulence is to reduce airspeed. Your aircraft manual most likely lists recommended airspeed for penetrating turbulence.
SECTION C AVIATION WEATHER SERVICES You know that as pilot in command of an aircraft, you are required to familiarize yourself with all available information before beginning a flight. For a flight under IFR or any flight not in the 1 vicinity of an airports that information must include the latest or most current weather reports and forecasts.
SURFACE ANALYSIS AND CONSTANT PRESSURE CHARTS Surface Analysis Chart Surface analysis chart often referred to as a surface weather map, is the basic weather chart. The chart is transmitted every 3 hours. The valid time of the map corresponds to the plotted observations. A date and time group in universal coordinated times (UTC) informs the user of when the conditions portrayed on the map were actually occurring. The surface analysis chart displays other weather information such as surface wind direction and speed, temperature, dew point, and various the other weather data. The surface analysis chart can show the pressure patterns by lines 275
called isobars, The isobars on a surface weather map represent lines of equal pressure reduced to sea level. It also includes the position of fronts, and areas of high or low pressure. Weather Chart Station Model
In the surface analysis chart, each reporting station is depicted on the chart by a small circle. The weather information pertaining to the station is placed in a standard pattern around this circle, and is called a station model (Figure 8-22). The meaning and symbol that the method is explained as follows of every project: 1) Total sky cover- The total sky cover is noted by special symbols, the meaning and symbol of total sky cover as Figure 8-23.
ltind direction total sky cover te11pe1·ature present weather visibility dewpoint
wind speed high cloud type •iddel cloud type sea level pressure pressure change in past 3 houx·s low cloud weather in the past 6 hour precipitation type sky cover cloud bass
Symbol
0 CD ~ ~ ()
Figure8-l2 Weather Chart Station Model
Total Sky Cover
Synbo1
Total
Sky
Cover
Stcy deer
E)
6/10
1/10 or less tlwl 1/10
~
7110 to 8/10
0
Breal
Z/10
to 3/10
•
4/10
5/10
®
10/10 Total ..ky ob-=ratioo
Figure8-l3 The Symbols ofTotal Sky Cover
2) Cloud type- In the surface analysis chart, the cloud type is noted by special symbols, the cloud name, English abbreviation and symbols are shown as Figure 8-24. S)'I!Ool
Cloud
T~
Symbol
Cloud Type
____.:>
Ci -Cirrus
:L_
Cs - Cirrostratus
\....v
Cc - Cirrocumulus
\...A...I
Ac - AltoCWIIUlus
LL_
Ns - Nimbostratus
L_
As - Altostratus
---
Fe - Frectocumulus
~
Cu - c,_,lus
- --
Fs - Frectoctratus
t6
TCu - T001ering cum.U=
~ '-F
Cb - CUftUlonillbus Sc - Stratocwoulus St - Stratus
Fn - Froctonimbus
Figure 8-24 The Symbols of Cloud Type
The sky cover of the low cloud is shown by a digit noted on the right of the symbol of the cloud, only the lowest cloud is noted it The bass of the low cloud is shown by digits, its unit is 100 meters, the height is used the above ground level (AGL). 3) Temperature and dew point- Temperature and dew point are noted by degrees Celsius, if they are the negatives, prefixed by"_". 4) Present weather- On the surface analysis chart, the present weather is shown with special symbols, Figure 8-25 is some important present weather and its symbol. 276
SY>Obol
Weather
S)fltlbol
--ti•
Li ch t f oa
Foa
r"
Suoko
c:>o
Hue
s $ -s-
•
*
Dust
r\ • r\
Send S01\d storm
lleatheT
S)nlbol
~~
Bl oorina snow
••
Drift ina s now
**• *• '\7 * '\1
Drhzl e U&ht rain
Li:ht snow
Thundennoroo
\teat her Cont i.nuous cb:i • z l e Continuous r ain Continuou.s anew
Rain on6 snow Rain shoooer
Snow shower
Thunder shower
FigureS-25 Present Weather Symbols
S) Visibility- Visibility is noted by kilometers.
6) Sea level pressure- Sea level pressure is always shown in three digits to nearest tenth of an hPa For 1 000 hPa or greater, prefix a " 10" to the three digits. For less than 1 000 hPa, prefix a "9" to the three digits. For example: if the sea level pressure shown in "132", the actual sea level pressure is 1 013.2 hPa
7) Pressure change in past 3 hours- the actual change is in tenths of an hPa For example: if the pressure change in past 3 hours shown in "26", the actual pressure change in past 3 hours is increased steadily or unsteadily by "2.6" hPa 8) Wind -The wind direction expressed with arrow pole, the direction of the arrow points to the station circle, shows the direction that wind comes from. The wind speed is expressed with long or short arrow feather. See Figure 8-26.
Figure 8-26 Symbols of the Wind Speed
9) Weather in the past- The weather in the past showed the weather phenomenon appearing in 6 hours before being observed in the past, express with Figure 8-27 listed the forms of the symbols.
()
•
Sky Cover Var iable OVC or
Bl{lf
~ Sand Storlll or
Slowi na Snow
o/oo Pos or Haze
•
*
R
'% ••
Snow or Rain and Snow Thunderstora Rain Shower or Snow Shower Rain
Dri,ule
Figure 8-27 Symbols of the Weather in tbe Past
277
10) 6 hours precipitation - Precipitation in 6 hours before the precipitation shows that is observed, it is expressed
--..=l
21
~"'0 - 21
with millimeter. If it is expressed with "T", showing that the precipitation in 6 hours is smaller than 0.1 mm. According to the explanation above, we can read the
UJ 081
4 .........,.. 5 16 15 ')..
Figure 8-28 The Record of a
information of the weather station.
Weather Station
In Figure 8-28, the total sky cover is breaks in overcast, the high cloud type is cirrus, the middle cloud type is altocumulus, the low cloud type is stratocumulus, the cloud cover of stratocumulus is 5110, the bass of the stratocumulus is 1 500 m (AGL). The temperature is 21
·c
and the dew point is 16 ·c. The present weather is smoke, visibility 4
kilometers. The sea level pressure is 1 008.1 bPa, the pressure change in past 3 hours have reduced 2.1 bPa. Southeast wind at 2 mls. The data of the weather in the past and the 6 hours precipitation seldom appear, so we can not often see them.
Analysis There are some another important contents in the surface analysis char, they are: isobars, pressure systems, fronts, same weather area, the center of pressure change in past 3 hours. 1) Isobars - Isobars are solid lines depicting the sea-level pressure pattern and are usually spaced at 2.5 hectopascal (hPa). Each isobar is labeled. For example, 1 000 signifies 1 000 bPa, and 997.5 signifies 997.5 bPa 2) Pressure systems- The letter "V' denotes a low pressure center, and the letter ''H'' denotes a high pressure center. The pressure of each center is indicated by a three- or four-digit number that is the center pressure in hPa (Figure 8-29).
Figure 8-29 Isobars and Pressure Systems
3) Fronts- The analysis shows positions and types of fronts by symbols in figure 8-30. The symbols on the front indicate the type of front and point in the direction toward which the front is moving. If the front has arrowhead-shaped symbols, it is a cold front On the colored surface analysis chart, it is noted by a blue solid line. If the front has half-moon shaped symbols, it is a warm front On the colored surface analysis chart, it is noted by a red solid 278
line. If the front has a arrowhead-shaped symbols and a half-moon shaped symbols they are on the other side, it is a stationary front (noted by a red and a blue solid line). If the two symbols are on the same side, it is a occluded front (noted by a purple solid line). !'ron' Type
SJI'Inbol
Col
8lut
Stationary Front
Blue Red
!'ron~
••
••
1'1...-m !'rent
Red
Oeelu
.. .. -·-• -·-•
Colour
Purple
Figure ~0 The Front Symbols on Surface Analysis Chart
4) Same weather area- On the surface analysis chart, the same weather areas are noted by a close line. At the center, there is a symbol showing that in this area every station has the same weather. The symbols of the same weather areas showing on Figure 8-31. IYeAther
SY!Qbol
Driz:le li cht Snow
Rain
~r
Snco.
~r
Til\llders t 0111>
(!) @ @ (f) @
Figure~l
Colour
9/eol her
Green
l"os
Green
Dus~
Green
Sand Storm
Cr~
Bloorins Snoor
Red
Strong 91ind
Svmbol
Colour
@
Yellow
@
troom
e(9 C9
Broom Green
Broom
Symbols of Same Weather Areas
S) The center of pressure change in past 3 hours- In the places that most greatly changes
are occur we show them with a dashed line circle, and if the pressure change value is a positive number, it is noted by a blue "+", and followed by the pressure change value. If the pressure change value is a Negative number, it is noted by a red "-", and followed by the pressure change value. See the Figure 8-32. o -21 --3
0 +02
0-28 ' / o -35 b -30 / I
, -3.7
o -~4 I
,o-3t '
0-25 --
/
I
0 -37
/
/o+21
o -11
I I
1
o +1o 1
,."0-23
/I
0 -03
' 'f
+2 . 3 ,' 0 +23 I
9 +19 I
o -18
0 +15
o +OO .~2 . ,
0 -11
I
/
,, __. .c:;:l9"'
I
o-o2 o +ll
0 +20
Figure 8-32 The Center of Pressure Change in Past 3 Hours
279
Using The Chart The surface analysis chart provides a ready means of locating pressure system and fronts. It also gives an overview of winds, temperatures, and dew point temperatures at chart time. When using the chart, keep in mind that weather moves and condition change. Using the surface analysis chart in conjunction with other information gives a more complete weather picture. Figure 8-33 is a section of a surface analysis chart, it shows a low pressure center with a warm front. In the middle of the picture, there is a cold front, and a precipitation area. In this weather area there are rain shower and thundershower. At the upper left corner there is a high pressure center. In the north of Beijing there is a strong wind and sandstorm area. The area arrow A pointed is a center of pressure change in past 3 hours, for past three hours, the pressure have increased 2.5 hPa.
Figure ~33 Surface Weather Map
Constant Pressure Charts Because the weather phenomenon takes place in the three-dimensional space, and analyses only according to one surface analysis chart is not enough obviously. In order to observe the weather condition of the three-dimensional space in detail, beside analysissing the weather map of ground, we should analysis the constant pressure charts. Space surface that point makes up that atmospheric pressure equal is called the constant pressure surface or isobaric surface. Because the same to go to atmospheric pressure of all parts its altitude can't the same, so isobaric surface is not a horizontal plane, but a surface as uneven as topography. Constant pressure charts are similar in many ways to the surface analysis chart in that they
280
show the pressure patterns and some weather conditions for reporting stations. These charts are prepared for selected values of pressure and present weather information at various altitudes. The standard charts prepared are the 850 hPa, 70 hPa, 500 hPa, 300 hPa, 250 hPa, and 200 hPa charts. Charts with higher pressure present information at lower altitudes, and Charts with lower pressure present information at higher altitudes. Figure 8-34 lists the general altitude (pressure altitude) of each constant pressure chart. Pressure I hPa
Pressure Altitude I foot
Pressure Altitude I meter
200
39000
12 000
250
34000
10500
300
30000
9000
500
18 000
5 500
700
10000
3 000
850
5 000
1500
Figure 8-34 Each Constant Pressure Chart with Its Pressure Altitude (MSL)
Plotted Data Data from each observation station are plotted around a station circle on each constant pressure chart. The circle identifies the station position. The data plotted on each chart are temperature, temperature-dew point spread, wind, height of the surface above sea level. The temperature and temperature-dew point spread are in degrees Celsius, wind direction is relative to true north, wind speed is in m.Js, and height is in meters. Figure 8-35 is a station model of the data plot
Figure 8-35 Constant Pressure Chart station Model
Illustrate Wind - Wmd direction and speed are plotted by symbols. The method to express the wind direction and speed are the same as it used in the surface analysis chart HGT - Plotted height of the constant pressure surface in meters above mean sea level. If data is missing, nothing is plotted in this position. T - Plotted temperature to the nearest whole degree Celsius. A below-zero temperature is prefaced with a minus sign. Position is left blank if data is missing. T-Td -Plotted temperature-dew point spread to the nearest whole degree Celsius. Position is left blank if data is missing. According to the explanation above, we can read the information of the record station. In Figure 8-36 (a), the temperature is 4 temperature-dew point spread is 5.2 the height
·c,
·c,
of the constant pressure surface is 3 040 m, northwest wind at 6 m.Js. We can know that this is a data of the 700 hPa isobaric surface. In Figure 8-36 (b), the temperature is - 18 ·c, temperature-dew 281
point spread is 3.5 "C, the height of the constant pressure surface is 5 800 m, southwest wind at 26 rnls. We can know that this is a data of the 500 hPa isobaric surface.
2o~ ~~ (o)
(b)
Figure 8--36 The Record of a Station
Analysis All constant pressure charts contain analyses of height and temperature variations. Variations of height are analyzesed by contours, variations of temperature by isothenns. Contours -Contours are lines of constant height, in meters, which are referenced to mean sea level. Contours are used to map the height variations of surfaces that fluctuate in altitude. They identify and characterize pressure systems on constant pressure charts Contours are drawn as solid lines on constant pressure charts, the contour interval is the height difference between analyzed contours the standard contour interval is 40 meters. Contours are identified by a three-digit code located on each contour, to determine the contour height value, affix "zero" to the end of the code. For example, a contour with a "312" code on the 700 hPa chart identifies the contour value as 3 120 meters. Also, affix a "one" in front of the code on all 200 hPa contours and on 250 hPa contours when the code begins with zero. For example, a contour with a "044" code on a 250 bPa chart identifies the contour value as 10 440 meters. The contour gradient is the distance between analyzed contours. Contour gradient identify slopes of surfaces that fluctuate in altitude. Strong gradients are closely spaced contours and identify steep slopes. Weak gradients are widely spaced contours and identify shallow slopes. The contour analysis displays height patterns. Common types of patterns are lows, highs, troughs, and ridges. Contours have curvature for each of these patterns. Contours patterns can be further characterized by size and intensity. Size represents the breadth of a system. Sizes can range from large to small. A large pattern is generally more than 1 000 miles across, and a small pattern is less than 1 000 miles across. Intensities can range from strong to weak. Stronger systems are depicted by contours with stronger gradients and sharper curvatures. Weaker systems are depicted by contours with weaker gradients and weaker curvatures. For example, a chart may have a large, weak high, or a small, strong low. Contour patterns on constant pressure charts can be interpreted the same as isobar patterns on the surface chart. For example, an area oflow height is the same as an area oflow pressure. Winds respond to contour patterns and gradients. Wmd directions parallel contours. In the Northern Hemisphere, when looking downwind, contours with relatively lower heights are to the left and contours with relatively higher heights are to the right. Thus, winds flow counterclockwise (cyclonically) around lows and clockwise (anticyclonically) around highs. (In the Southern 282
Hemisphere these directions are reversed.) Winds that rotate are termed circulations. Wmd speeds are faster with stronger gradients and slower with weaker gradients. In mountainous areas, winds are variable on pressure charts with altitudes at or below mountain crests. Contours have the effect of"chanoeling" the wind. Isotherms- Isotherms are lines of constant temperature. An isotherm separates colder air from warmer air. Isotherms are used to map temperature variations over a surface. Isotherms are drawn as bold, dashed lines on constant pressure charts. Isotherm values are identified by a two-digit block on each line. The two digits are prefaced by "+" for above-freezing values as well as the zero isotherm and "-" for below-freezing values. Isotherms are drawn at 4-degree intervals on each chart. The zero isotherm separates the above-freezing and belowfreezing temperatures. Isotherms gradients identifY the magnitude of temperature variations. Strong gradients are closely spaced isotherms and identify large temperature variations. Weak gradients are loosely spaced isotherms and identifY small temperature variations.
Trough-line and shear line- An elongated area of low pressure to be called trough, with the lowest pressure along a line marking maximum cyclonic curvature to be called trough-line. The shear-line is a field discontinuous line of wind with cyclone type shear, the wind direction, wind speed of both sides in shear-line have obvious differences. Trough-line and shear-line are the weather systems that are often seen on constant pressure charts, it is the important part in the synoptic analysis too.
Using the Chart Figure 8-37 is a constant pressure chart of700 bPa, In this upper air weather map, we can see that near Lanzhou it is a high pressure center, there is a high-pressure system in the eastern area of China too. There is a low pressure system in the area of Mongolia, EF is a trough-line. MN is a shear-line appearing between two pieces of high pressure: Near Beijing it is a warm air center, there is a cold center in the east of Korea Peninsula You can meet the turbulence while crossing the trough-line or the shear line while flying.
The upper air constant pressure chart can be used to locate the jet stream and its associated turbulence and wind shear. When there is a large change in wind speed over a short distance, the probability of turbulence is greatly increased. Since the jet stream is associated with discontinuities in the temperature lapse rate at breaks in the tropopause, closely spaced isotherms indicate the possibility of turbulence or wind shear.
In 300 bPa, 250 bPa or 300 bPa constant pressure charts, the area where the wind speed is greater than 30 m/s is the position where the upper jet locations. The torrent in the high altitude is a contour compact district Figure 8-38 is a constant pressure chart of 300 bPa, in this upper air weather map, we can see a upper jet is set out from the Caspian Sea, through the Balkash Lake, entry Xinjiang of China, then through Chengdu and Beijing, enter the Northeast area of Asia The upper jet is a very strong place of a wind shear, and flies in the upper jet or crosses it, will meet the stronger clear air turbulence (CAT). 283
Figure 8-37 A Constant Pressure Chart of 700 hPa
Figure 8-38 Use Upper Air Weather Map to Judge the Upper Jet
284
SIGNIFICANT WEATHER PROGNOSTIC CHARTS Significant weather prognostic charts, called progs, it depicts weather conditions that are forecast to exist at a specific time in the future shown on the chart, portray forecast weather to assist in flight planning. Each valid time is the time at which the forecast conditions are expected to occur. Forecasts are made from a comprehensive set of observed weather conditions. The observed conditions are extended forward in time and become forecasts by considering atmospheric and environmental processes. Forecasts are made for various periods of time. A 12-hour prog is a forecast of conditions which has a valid time 12 hours after the observed data base time, thus a 12-hour forecast A 24-hour prog is a 24-hour forecast, and so on. For example, a 12-hour forecast based on OOZ observations is valid at 12Z. Altitude information on the prog charts is referenced to mean sea level (MSL) and compatible with aviation. Altitudes below 18 000 feet are true altitudes while above 18 000 feet are pressure altitudes or flight levels (FL). The significant weather prognostic charts are generally divided in three kinds of height layer to offer: Low-Level Significant Weather Prog Chart (SWL)- the flight height is lower than FLl 00 (10 000 feet). Middle-Level Significant Weather Prog Chart (SWM) -the flight height is from FL 100 to FL250 (10 000 feet-.... 25 000 feet). High-Level Significant Weather Prog Chart (SWH)- the flight height is from 25 000 feet to 63 000 feet. This encompasses FL250 to FL630. Main Content
There are the following several items in the main content of significant weather prognostic charts: 1) Significant weather- (or calls the abominable weather), see form Figure 8-39 in kind and symbol ofthe significant weather, express with the symbol on the progs. 2) Important weather system- For instance ground fronts line, high or low pressure center, convergence line and the intertropical convergence zone and so on (whether system symbols are shown in Figure 8-40). 3) Cloud accompanying with the significant weather-The clouds accompanying with the significant weather are described by simple language, the cloud type is noted by abbreviations. On the significant weather prognostic charts, the significant weather and cloud district range are enclosed with the wavy line. Some important weather and cloud also stamp the height of bass and tope, also prove with the simple language sometimes. Cloud type: CI = Cirrus
CC = Cirrocumulus
CS =Cirrostratus
AC =Altocumulus 285
~
Thunderstorms
9
Tropical cyclone
,-~
Severe squall line
-A-
Moderate turbulence
_A_
Severe turbulence
•'+'
, ~/,/,///
*v + s -s.
Snow
Sevt;tre aircraft icing
00
Widespread hcu:e
Widespread fog
-
Widespread mist
r"'
Widespread smoke
~
Freezjng precipitation
Moderate aircraft icir'lg
--
Rain
/1//H
Mountain waves
'fit/
Oriule
~
Radioactive materials in the atmosphere
t:l
Volcanic eruption
M
Mountain obscuration
Shower }
1:::.
Hail
Widespread blowing snow Severe sand or dust haze W idespread sandstorm or dust storm
•
Visible ash cloud
Figure 8-39 Symbols for Significant Weather
•- -•
-· -· -• -•
...._
tte.
Occluded front at the surface Quasi-stationary rront at the surf.uce
~-'Lz"o
~
tte.
1o
,00
:n
Tropopause Low
®
Tropopause Level
<8>
380
'""
I n.
300
·t-
Frae2lng level
~
Qtl I
1
III:
iropopause High
...
Position. speed and level of max. wind
tJl, Convergence line
~
rJ;) 0
~ W1nd
. -. ••'L
Cold front at the surfaco Warm front at the surfoce
Intertropical convergence zone Stato of the sea Sea-surfaco temperature
Wido!ilprend Strong surface wind • <
fL 340
..
arrcw.~s Indicate tho ma~tmum wind In Jet and tho fl'8,nt level at which 1t occurs. S•gnlflc.ont chongos (&pood o 20 knoltl or I'T'IQrO. 3QOO f t OBB 1f pm~ICj()bJO) '" ll~nt lovol) orv markod by tho doublo bar. In tho cxamplo. at lho ooublo bar tne Wind spood ts !> l
11'10 l'loavy hno dollnom1np ti"'G JOt O)(IS b~>gtnsfoncts at tho points whom a w ind speod ol bO kmlh - 80 k ts forecast • Tnla symbol rofors to Widespread !Wrlacewtnd s~ds oxcoed1ng tiO kmJh (30 kt)
Figure 8-40 Fronts and Convergence Zones and Other Symbols Used
286
AS = Altostratus
NS =Nimbostratus
SC = Stratocumulus
ST= Stratus
CU=Cumulus
CB =Cumulonimbus
Cloud amount: Clouds except CB FEW= few (118 to 2/8)
SCT =scattered (3/8 to 4/8)
BKN =broken (5/8 to 7/8)
OVC = overcast (8/8)
SKC = sky clear (0/8). CBonly
LOC
= some places have CBs (local)
!SOL
= individual CBs (isolated)
OCNL = well-separated CBs (occasional) FRQ
=CBs with little or no separation (frequent)
EMBD =CBs embedded in layers of other clouds or concealed by haze (embedded) Ooud heights: Heights are indicated on SWH and SWM charts in flight levels (FL), top over base. When XXX is used, tops or bases are outside the layer of the atmosphere to which the chart applies.
In SWL charts: i) Heights are indicated as altitudes above mean sea level; ii) The abbreviation SFC is used to indicate ground level. 4) Depicting of lines and systems on specific charts Models SWH and SWM- Significant weather charts {high and medium) Scalloped line
=demarcation of areas of significant weather
Heavy broken line
= delineation of area of CAT
Heavy solid line interrupted By wind arrow and flight level
= position of jet stream axis with indication of wind direction, speed in KT or kmlh and height in flight levels.
Figures on arrows
= speed in KT or km/h of movements of frontal system
Flight levels inside small rectangles = height in flight levels of tropopause at spot locations, e.g. 340. Low and High points of the tropopause topography are indicated by the letters L or H respectively inside a pentagon with the height in flight levels. Model SWL - Significant weather charts (low level) X
= position of pressure centers given in hectopascals
L
= center of low pressure
H
= center of high pressure
Scalloped lines
= demarcation of area of significant weather 287
Dashed lines =altitude ofO"C isotherm in feet (hectofeet) or metres NOTE: 0 "C level may also be indicated by 00: 060, i.e. 0 "C level is at an altitude of 6 000 ft. Figures on arrows = speed in KT or lanJh of movement of frontal systems, depressions or anticyclones Figure inside the state of the sea symbol =total wave height in feet or metres Figure inside the sea-surface temperature symbol = sea-surface temperature in "C. Figures inside the strong surface wind symbol =wind in KT or km/h. S) Arrows and feathers Arrows indicate direction. Number of pennants and/or feathers correspond to speed. Pennants correspond to 50 kt or 93 kmlh Feathers correspond to 10 kt or 18 kmlh Half-feathers correspond to 5 kt or 9 kmJh 1 knot = 1.852 kilometres per hour low-level Significant Weather Prog Chart (SWL)
The low-level significant weather prog chart forecasts weather conditions from the surface to the FLIOO. In the pictures, it denotes the fronts and its movement that is expected (express direction with arrow point, show the speed of moving with number value, unit km/h or K'I). And it indicates the various kinds of important weather, precipitation and the weather phenomenon which cause visibility lower than 5 000 m on a large scale (whether visibility use number value, unit meter), and the area and height to be influenced. Figure 8-41 is a low-level significant weather prog chart, from this chart we can see that on the
3000M
I o=
o"o I
LOC 1500 M
SCT SC OCNL 3000M 1 o:
Figure 8-41
288
oso I
Significant Weather Prog Chart (low level)
course from Shenyang to Harbin, the weather system passing is a cold front near Shenyang, a warm front near Harbin, There are the significant weather that may be met on the course : rainfall near Harbin, the area of Changchun is remarkable mountain waves, there is freezing precipitation, the thunderstonns, there is moderate and severe turbulence, near Shenyang. there is moderate aircraft icing.
Middle-level Significant Weather Prog Chart (SWM) Compared with the low level Prog Charts, the middle level significant weather Prog charts have much different. There is no surface visibility, no low pressure or high pressure centers, no altitude of 0 "C isotherm, no sea-surface temperature and no stat of the sea, and have added the meteorological condition of flight appeared in Middle altitude. There is the weather: 1) Heavy broken line delineation of area of clear air turbulence (CAT), and its intensity is
denoted by symbols. 2) Heavy solid line show the position of jet stream axis with indication of wind direction, interrupted by wind speed in KT or km/h and height in flight levels. 3)Ash cloud (AV). Figure 8-42 is a middle-level significant weather prog chart, on this chart we can see that on the course from Haokou to Guangzhou, the weather system passing is the intertropical convergence zone and a upper jet near Sanya, a quasi-stationary ftont near Guangzhou. There are the significant weather that may be met on the course: severe clear air turbulence near Haikou, the north ofHaikou
is remarkable mountain waves, the thunderstorms, there is severe turbulence, and moderate aircraft icing.
Guangzhou 0
0
Sanya
Figure 8-42 Significant Weather Prog Cbart (medium level)
289
High-level Significant Weather Prog Chart (SWH)
The high-level significant weather prog chart forecasts conditions from 25 000 feet to 60 000 feet This encompasses FL250 to FL600. High-level significant weather prog chart have predicted all weather phenomenon of the middle level, Unlike it the cloud only predicts cumulonimbus, still have the height in flight levels of tropopause, the unit is 100 feet Figure 8-43 is a high-level significant weather prog chart, on this chart we can see that on the course from Chongqing to Kweilin, the weather system passing is a worm front, a severe squall line and a upper jet. There are the significant weather that may be met on the course: severe clear air turbulence and the thunderstorms.
~ Chengdu 0
Figure 8-43 Signific.a nt Weather Prog Chart (high level)
WIND AND TEMPERATURES ALOFT FORECAST Wind and temperatures aloft forecast is supplied in chart form to flight crew members before departure, the charts shall be fixed time prognostic charts for standard isobaric surfaces. This prediction is very important while doing the flight plan. Upper wind and upper-air temperatures forecast charts usually for points separated by no more than 500 km (300 nrn) and for the following regular height layers. FL 50 (850 hPa) FLlOO (700 hPa) FL 180 (500 bPa) FL 240 (400 bPa) FL 300 (300 hPa) FL 340 (250 hPa) FL 390 (200 bPa) FL 450 (150 hPa) On upper wind and upper-air temperatures forecast charts, the wind speed is noted by knots, the method of marking of the wind speed as Figure 8-44: 290
In the wind and temperatures aloft forecast charts, the temperatures is noted by degrees Celsius they are all negatives unless prefixed by "+". Now, we can read the infonnation about Figure 8-45, the wind direction is southwest, wind speed is 60 knots, temperatures is -48 "C. 5 knots ( 9. 2 kll/ h)
\...____
10 knots (18. 5 km/ h)
L__ L_
50 knots (92. 5 km/h)
~48
Figure 8-U The Method of Marking of the Wind Speed
Figure 8-45 Wind and Temperature Aloft
Figure 8-46 is a party of a wind and temperatures aloft forecast chart, in this picture we know that in this area all lean towards the west wind, strong wind area lies in the Northeastern part pursued, low temperature area lie the Northeastern part pursued.
b,,:
:
- - ~~
· ~ - -~ •. .,.,.y · ·~a.'l ~8
HI
-..;y
\.9
•.
so 50
Figure 8-46 Wind and Temperatures Aloft Forecast Chart
Where upper wind and upper air temperature information is supplied in tabular form, it should include data for the same flight levels as for upper-air charts. This information should be given fpr Examples of the form of presentation of tabular forecasts of upper winds and upper-air temperatures are given in Figure 8-47.
24260 18 '26() 10250 05150 02 090
Ji)- 29
25 - 18 10-i)J 10 + 03
25 + 04
Figure 8-47 Tabular Forecasts of Upper Winds and Upper-air Temperatures
291
In Figure 8-47, the boxes refer to spot winds degrees true and knots at intersections of the latitude/longitude lines covered by the box. Temperatures in degrees Celsius, heights are above MSL (thousands of feet). Example ''24 260 40 - 28", the ones that showed are: height 24 000 feet, wind 260 degrees at 40 knots, temperature -28 ·c.
AVIATION ROUTINE WEATHER REPORT (METAR) During preflight planning, the surface aviation weather report allows you to assess existing conditions and evaluate the accuracy of forecasts. You do this by comparing current reports with the forecast weather for the same time period to see if the weather is materializing as forecast. You can also review several previous reports to get a general idea of the weather trend. A current report also indicates weather your destination is presently above VFR or IFR minimums, as appropriate. If it is not and the forecast calls for only slight improvement by your estimated time arrive, the destination weather may not permit you to land. The surface report also is important at airports without a control tower or flight services station, since the last surface observation is the latest official weather available at that location. The aviation routine weather report contains various weather elements in a coded form. The elements of the report are: A. 1)'pe of report; B. ICAO station identifier; C. Date and time ofreport; D. Wind; E. VISibility; F. Runway visual range (RVR) (as required); G Weather phenomena; H. Sky condition; I. Temperature/dew point group; J. Altimeter setting. Format of the METAR Telegram METAR {
or SPECI
ecce
(1)
(2)
VVVVDv (5)
292
YYGGggZ (3)
{
KMHor MPSorx
KT
(4)
{ RDrD!VrVrVrVri RDrDIVrVrVrVrVVrVrVrVri (6)
w·w· (7)
NsNsNshshshs ( CC) or VVhshshs EiJ4 { SKC
T'T'!rd'Tl
(9)
(8)
(10)
Key to the Metar Observations Type ofreport (METAR or SPEC!) There are two types of surface aviation weather reports- the METAR and the aviation selected special weather report SPEC!. The METAR is taken on the hour, the SPECI is an unscheduled observation indicating a significant change in one or more elements of the weather. ICAO station identifier (CCCC) The METAR code uses ICAO 4-letter station identifiers, some city's 4-letter station identifiers as Figure 8-48. Station
identifier
Station
identifier
Beijing
ZBAA
Shanghai
zsss
Tianjing
ZBTJ
Guangmou
ZGGG
Lanzhou
ZLLL
Kunming
ZPPP
Urumchi
zwww
shenyang
zyTX
Cbengdu
zuuu
Guanghan
ZUGH
Hong Kong
VHHH
Taibei
RCTP
Tokyo
RJAA
Seoul
RKSS
Figure 848 4-letter Sbtion Identifiers
Time ofreport (YYGGggZ) The time the observation is taken is transmitted as a six-digit time group appended with a Z :o denote Coordinated Universal Time (UTC), indicate the date, hour and minute.
Wind (dddfiGfmfm MPS) The wind is reported as a five-digit group, the first three digits is the direction the wind is blowing from in ten's of degrees, or "VRB" if the direction is variable. The next two digits is the speed in meters per second (MPS), if the wind is gusty, it is reported as a "G" after me speed followed by the highest gust reported. 00000 MPS for calm; for METAR, if direction vanes 60 degrees or more, Variability appended, e.g. 180V260.
Vzsibility (VVVVDv VxVxVxVxDv) VIsibility is reported in meters. When the visibility is not the same in different directions the lowest visibility should be reported and its general direction in relation to the site of meteorological station indicated by reference to one of the eight points of the compass. VxVxVxVxDv Shows the greatest visibility and direction. "9999" express visibility ~ 10 kilometers. Runway visual range (RVR) CRDrD/VrV,V,Vri)
The ''R" identifies the group followed by the runway heading, a "f', and the visual range in 293
meters. The letter "i" shows the change of the visual range in the runway in 10 minutes before observes. "U" show the visual range in the runway has the tendency to obviously rise when observing. ''D" shows there are obvious downward trends in the visual range in the runway when observes, "N" shows there is no obvious change in the visual range in the runway when observes.
Weather phenomena In METAR, weather is reported in the format: Intensity, Proximity, Descriptor, Precipitation,
Obstruction to visibility, or Other. Intensity- applies only to the first time of precipitation reported. A "-" denotes light, no symbol denotes moderate, and a"+" denotes heavy. Proximity- applies to and reported only for weather occurring in the vicinity of the airport (between 5 and 10 miles of the center of the airport runway complex). It is denoted by the letters "VC". Descriptor- these seven descriptors apply to the following precipitation or obstructions to visibility: TS- thunderstorm SH-shower
BL- blowing DR -low drifting
FZ- freezing
.MI- shallow
BC-patches Precipitation -there are eight types of precipitation in the METAR code: RA- rain
GR- bail
DZ- drizzle
GS -small haiVsnow pellets
SN- snow
PE- ice pellets
SG- snow grains
IC- ice crystals
Obstruction to visibility- there are eight types of obstructing phenomena in the METAR code: BR-mist
HZ-haze
SA-sand
VA- volcanic ash
FU-smoke DU-dust
FG-fog PY-spray
Note: fog (FG) is reported only when the visibility is less than one kilometer otherwise mist (BR) is reported. Other- there are five categories of other weather phenomena which are reported when they occur. SQ-squall
SS- sandstorm
DS- duststorm
PO- dust/sand whirls
FC- funnel cloud/tornado/waterspout Examples +SHRA- heavy shower of rain TSSN- moderate thunderstorm with snow
294
FZDZ- moderate freezing drizzle SNRA - moderate snow and rain +TSSNGR- heavy thunderstorm with snow and hail Sky condition The sky condition as reported in METAR represents a significant change from the way sky condition is currently reported. In METAR. sky condition is reported in the format: Amount, Height, (Type), or Vertical VIsibility. Amount- the amount of sky cover is reported in eighths of sky cover, suing the contractions: SKC-clear (no cloud) FEW-few (1/8 to 2/8's of clouds) SCT-scattered (3/8's to 4/8's of clouds) BKN-broken (5/8's to 7/8's of clouds) OVC-overcast (8/8's of clouds) Height- cloud basses are reported with three digits in 30 of meters, the height is used the above ground level (AGL). (Type)- if towering cumulus clouds (TCU) or cumulonimbus clouds (CB) are present, they are reported after the height which represents their base. Vertical Visibility- total obscurations are reported in the format "VVhhh" where VV denotes vertical visibility and "hhh" is the vertical visibility in 30 of meters. CAVOK-when it is better, word yards ofCAVOK can be used for replacing the visibility group, weather phenomenon group and cloud group, its condition is: • Potential visibility is 10 kilometers or the above; • 1 500 meters under cloudless, and the sky does not have cumulonimbus, cumulus, etc; • There is no significant weather phenomenon, such as precipitation, thunderstorm, sandstorm, blowing snow, etc. Temperature/dew point Temperature and dew point are reported in a two-digit form in degrees Celsius. Temperatures below zero are prefixed with an ''M." Altimeter setting Altimeter settings are reported in a four-digit format in whole hectopascal (bPa), denote with a ''Q", e.g. Ql003. Examples and Explanations
Examplel METAR ZGGG 061800Z 20007G liMPS 2000 TSRA SCT030 BKN050 (CB) 28/25 Q992 = Explanation Aviation Routine Weather Report, Guangzhou, date 06, time 1800UTC, wind 200 at 7 ,gusts liMPS, visibility 2 000 meters, moderate thunderstorm with rain, 900 scattered, I 500 broken, cumulonimbus, temperature 2s·c, dew point 2s·c. altimeter 992 hPa Example2 295
METAR YUDO 221630Z 24015KMH 0600 Rl2/1000U FG DZ SCT010 OVC020 17/16 Ql 018 BECMG TL1700 0800 FG BECMG AT1800 9999 NSW = Explanation Routine report for Donlon!Intemational• issued on the 22nd of the month at 1630 UTC; surface wind direction 240 degrees; wind speed 15 kilometres per hour; visibility 600 metres; ""Wlway visual range representative of the touchdown zone for runway 12 is 1 000 metres and the runway visual range values have shown an upward tendency during previous 10 minutes (RVR ~endency to be included in 'METAR only); fog and moderate drizzle; scattered cloud at 300 metres; overcast at 600 metres; air temperature 17 degrees Celsius; dew-point temperature 16 degrees Celsius; QNH 1018 hectopascals; trend during next two hours visibility becoming 800 metres in fog by 1700 UTC; at 1800 UTC visibility becoming 10 kilometres or more and nil significant weather. Example3 SPECI RKSS 221315Z VRB03MPS 0600 +SN FG VV002 M01/M03 Ql 001 = Explanation Aviation selected special weather report, Seoul, date 22, time 1315UTC, wind variable at 3 MPS, visibility 600 meters, heavy snow and fog, vertical visibility 60 meters, temperature -1 "C, dew point -3 "C, altimeter 1 001 hPa The equal sign signifies the end of the 'METAR Example4 SPECI YUOO 151115Z 05025G37KT 1200NE 6000S +TSRA BKN050CB 25/22 Q1008 T.aMPO TL1200 0600 BECMG AT1200 8000 NSW NSC = Explanation Selected special report for Donlonllntemational• issued on the 15th of the month at 1115 UTC; surface wind direction 50 degrees; wind speed 25 knots gusting between 10 and 37 knots (minimum wind speed not to be included in SPECI); visibility lowest to north east at 1 200 metres, visibility 6 000 metres to south (directional variations to be included in SPECI only; visibility representative of the runway included in the local special report); heavy thunderstorm with rain; broken cumulonimbus cloud at I 500 metres; air temperature 25 degrees Celsius; dew-point temperature 22 degrees Celsius; QNH 1 008 hectopascals; trend during next two hours, visibility temporarily 600 metres from 1 115 to 1 200, becoming at 1200 UTC visibility 8 Ion, thunderstorm ceases and nil significant weather and nil significant cloud.
TH~
TERMINAL AERODROME FORECAST (TAF)
The tenninal aerodrome forecasts are prepared to give a description of expected conditions at an airport and within a 5 nautical miles radius of a runway complex. A tenninal aerodrome forecast IS a concise statement of the expected meteorological conditions over a specified time period, usually 9 hours and 24 hours. The descriptors and abbreviations used in the TAF are the same as those used in the METAR report. • Fictitious Location
296
Format of the TAF Telegram
TAF
ecce
(YYGGggZ)
YYGIGJG2G2
dddtlGfmfm
{KMH~ MPS !il(; KT
(2)
(1)
vvvv
(4)
(3)
' W'W
{
h(
~~:.hshshshs cc) y
YUSLJsUs
(5)
CAVOK
(TTFTF/G~FZ)
SKC !il(; NSC
m
oo ( 6Jchj)lj)litL) (10)
~
~
( SBhshshstL )
PROBC2~
(11)
(12)
TEMPORARY CONDITION (13)
FORECAST CHANGE (14)
Key to the TAF • l)'pe- Routine (TAF), Amended (TAF AMD) • Location- ICAO four-letter location identifier • Issuance date/time-A six-digit group giving the date (first two digits) and the time (last four digits ) in UTC. • Valid period- The valid period of the forecast is a two-digit date followed by the two-digit beginning and two-digit ending hours in UTC. Routine TAFs are valid for 9 hours or 24 hours. The 24 hours forecast are issued four times daily at OOOOZ 0600Z 1200Z 1800Z All ending times throughout the TAF of OOZ are indicated by the number of24. Examples 111818 Forecast valid from the eleventh at 18Z to the twelfth at 18Z. 300024 Forecast valid from the thirtieth at OOZ to the first at OOZ. Forecast - Body of the TAF has a basic fonnat: WINDMSIBILITY/WEATHER/SKY CONDITION • Wind- Five digits followed by ''MPS", the first three are direction and last two speed. Wmd gust denoted by the letter "G" appended to the wind speed followed highest gust Variable wind direction noted by "VRB" where direction usually appears, a calm wind (2 m/s less) is shown as 00000 MPS. • Visibility- Visibility is reported in meters. The forecast methods are the same as those used in the METAR report.
297
• Weather- Weather phenomena significant to aviation are included and follow a format which is: Intensity or Proximity/Descriptor/Precipitation/Obstruction/visibility/Other. "VC" applies to weather conditions expected to occur in the vicinity of the airport (between a 5 to 10 statute mile radius of the airport), but not at the airport itself. Therefore, "VCTS" in a Terminal Aerodrome Forecast indicates thunderstorms are expected between a 5 to 10 statute mile radius of the airport, but not at the airport itself.
If no significant weather is expected to occur during a specific time period in the forecast, the weather group is omitted or expressed with "NSW". However, if after a time period in which significant weather has been forecasted, a change to a forecast of "no significant weather" occurs, the contraction NSW (no significant weather) will appear as the weather included in BECMG (becoming) or TEMPO (Temporary) groups. NSW will not be used in the initial time period of a TAF or in FM The FM group is used when a rapid and significant change, usually occurring in less than 1 hour, in prevailing conditions is expected. Appended to the FM indicator Is the four-digit hour and minute the change is expected to begin. The forecast is valid until the next change group or the end of the current forecast Examples FM1500 16008G14MPS 4000 SCT040BKN250 FM0200 32005MPS 1000 TSRA FEWOIO BKN050CB • Sky condition- Sky condition is presented in a format which includes Amount/Height (Type) or Vertical VISibility. The forecast methods are the same as those used in the METAR report. If there is no significant cloud, expressed with ''NSC". CAVOK-when it is better, word yards of CAVOK can be used to forecast the visibility group, weather phenomenon group and sky condition group, its standard is the same as in theMETAR. • Temperature predicted-"T" is the yard denote for the temperature, ''TFTF" is the predicted temperature in degrees Celsius. Temperatures below zero are prefixed with an
''M!' Ex: ''TM03/04Z", means "It is estimated that the temperature is- 3°C at 0400UTC". • Icing- ''6" is the yard denote for icing, ''hihJlt is the height of the icing layer bottom (= yard numberx30 m ), ''tL" is the thickness of the icing layer(= yard numberx300 m ), "Ic" is the type of the icings, the method to work out telegram see Figure 8-47. Ex: "631 002", means ''there exist light icing in precipitation, the height of the icing layer bottom is 3 000 m, the thickness of the icing layer is 600 m." • Turbulence- "5" is the yard denote for the turbulence, "hshahs" is the height of the turbulence layer bass(= yard numberx30 m ), ''tL" is the thickness of the turbulence layer(= yard numberx300m ), "B" is the type of the turbulence, the method to work out telegram is shown in Figure 8-49. 298
Ex: "561204", means "there exist severe turbulences not frequent in clear air, the height of the turbulences layer bottom is 3 600 m, the thickness of the turbulences layer is 1 200m." Type yard
The type of turbulences
The type of icings
0
No icing
No turbulences
1
Light icing
Light turbulences
2
Light icing in cloud
Moderate turbulences not frequent in clear air
3
Light icing in precipitation
Moderate turbulences frequent in clear air
4
Moderate icing
Moderate turbuJences not frequent In cloud
5
Moderate icing in cloud
Moderate turbulences frequent in cloud
6
Moderate icing in precipitation
Severe turbulences not frequent in clear air
7
Severe icing
Severe turbulences frequent in clear air
8
Severe icing in cloud
Severe turbulences not frequent in cloud
9
Severe icing in precipitation
Severe turbulences frequent in cloud
Figure 8-49 The type of icings and turbulences
• Other- Probability - A PROB40 HHhh group in a TAF indicates the probability of occurrence of thunderstorms or other precipitation. PROB40 indicates a 40% - 49% chance and PROB30 indicates a 30% - 39% chance. The Iffihh is a four-digit beginning and ending time. • Temporary conditions-Changes usually lasting less than an hour. TEMPO HHhh (beginning and ending time). • Forecast change groups- Used when a significant or permanent change is expected. The change is indicated by the group F.MHH (from) and BECMG (becoming) followed by HHhh (times).
The Telegram Examples Example 1 TAF ZUUU 111140Z 111212 13005MPS 5000 BKNIOO TEMPO 1214 3500 BR FM 1500 16008G15MPS 6000 SCT040 BKN250 T16/20Z FM 0000 14006MPS 3500 BKN080 OVC150 PROB40 0004 2000 TSRABKN030CB FM 0400 14008MPS 3000 SCT040 OVC080 TEMPO 0408 1500 TSRA OVC030CB BECMG 0810 32007MPS =. Explanation Aviation terminal forecasts Chengdu prepared on the 11th at 1140Z, valid period from the 11th at 1200Z until the 12th at 1200Z, wind 130 at 5 mls, visibility 5 000 m, ceiling 3 000 m broken, temporary conditions between 1200Z and 1400Z, visibility 3 500 m, mist. From 1500Z, wind 160 at 8 m/s gusting to 15 rn/s, visibility 6 000 m, I 200m scattered, ceiling 7500m broken, temperature is l6°C at 2000UTC. 299
From OOOOZ, wind 140 at 6 m/s, visibility 3 500 m, ceiling 2 400 m broken, 4 500 m overcast, 40% probability between OOOOZ and 0400Z, visibility 2 000 m, thunderstorms with moderate rain showers, ceiling 900 m broken with cumulonimbus. From 0400Z, wind 140 at 8 m/s, visibility 3 000 m, 1200 m scattered, ceiling 2 400 m overcast. Temporary conditions between 0400Z and 0800Z, visibility 1 500 m, thunderstorms with moderate rain showers, ceiling 900 m overcast with cumulonimbus, becoming between 0800Z and 1OOOZ, wind 320 at 7 m/s. The equal sign signifies the end of the TAF. Example2 TAF YUDO 160000Z 160624 13018KMH 9000 BKN020 BECMG 0608 SCT015CB BKN020 TE1\1PO 0812 17025G40KMH 1000 TSRA SCTOlOCB BKN020 FM1230 15015KMH 9999 BKN020 BKN100 T26/18Z 621203 540502 = Meaning oftbe for~ast Aerodrome forecast for Donlon!Jnternationat issued on the 16th of the month at 0000 UTC valid from 0600 UTC to 2400 UTC on the 16th of the month; surface wind direction 130 degrees; wind speed 18 kilometres per hour; visibility 9 kilometres, broken cloud at 600 metres; becoming between 0600 UTC and 0800 UTC, scattered cumulonimbus cloud at 450 metres and broken cloud at 600 metres; temporarily between 0800 UTC and 1200 UTC surface wind direction 170 degrees; wind speed 25 kilometres per hour gusting to 40 kilometres per hour, visibility 1 000 metres in a moderate thunderstorm with rain, scattered cumulonimbus cloud at 300 metres and broken cloud at 600 metres; from 1230 UTC surface wind direction 150 degrees; wind speed 15 kilometres per hour; visibility 10 km or more; broken cloud at 600 metres and broken cloud at 3 000 metres. Temperature is 26 oc at 1800UTC, there exist light icing in cloud, the height of the icing layer bottom is 3 600 m, the thickness of the icing layer is 900 m. There exist Moderate turbulences not frequent in cloud, the height of the turbulences layer bottom is 1 500m, the thickness of the turbulences layer is 600 m. Note - In this example, the primary units "kilometres per hour" and "metre'' were used for wind speed and height of cloud base respectively. However, units "knot" and "foot" may be used instead.
IN- FLIGHT AVIATION WEATHER ADVISORIES In-flight aviation weather advisories are forecasts to advise en route aircraft of development of potentially hazardous weather. There are three types of in-flight aviation weather advisories- the Significant Meteorological Information (SIGMET), the Airmen's Meteorological Information (AIRMET), and Convective SIGMET. In the In-flight Aviation Weather Advisories the more important are the SIGMET and AIRMET. They are issued to alert pilots to potentially hazardous weather not adequately forecast in the current Area Forecast (FA).
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Significant Meteorological Information (SIGMEl) A SIGMET is issued to advise pilots of weather considered potentially hazardous to all categories of aircraft, and is valid for the period stated in the advisory. SIGMET information shall be issued by a meteorological watch office and shall give a concise description in abbreviated plain language concerning the occurrence and/or expected occurrence of specified en-route weather phenomena, which may affect the safety of aircraft operations, and of the development of those phenomena in time and space.
The Content ofSIGMET 1) at subsonic cruising levels: thunderstorm -obscured
OBSCTS
-embedded
EMBDTS
-frequent
FRQTS
-
squall line
SQLTS
-
obscured with hail
OBSCTSGR
-embedded with hail
EMBDTSGR
-frequent, with hail
FRQTSGR
-
squall line with hail
SQLTSGR
tropical cyclone -tropical cyclone TC (+ cyclone name) with 10-minute mean surface wind speed of 63
km/h (34 KT) or more turbulence -severe turbulence SEV TURB icing -severe icing SEV ICE - severe icing due to freezing rain SEV ICE (FZRA) mountain wave. -severe mountain wave SEV MTW duststorm -
heayy duststorm HVY DS
sandstorm -
heayy sandstorm HVY SS
volcanic asb -
volcanic ash VA(+ volcano name, if known)
2) at transonic levels and supersonic cruising levels: turbulence -moderate turbulence MOD TURB -severe turbulence SEV TURB 301
cumulonimbus -isolated cumulonimbus ISOL CB -occasional cumulonimbus OCNL CB -frequent cumulonimbus FRQ CB
hail -bailOR
volcanic ash - volcanic ash VA (+ volcano name, if known) SIGMET information shall not contain unnecessary descriptive material. In describing the weather phenomena for which the SIGMET is issued, no descriptive material additional to that given in a) and b) shall be included. SIGMET information concerning thunderstorms or a tropical cyclone shall not include references to associated turbulence and icing. SIGMET information shall be cancelled when the phenomena are no longer occurring or are no longer expected to occur in the area
Format and Exchange ofSIGMET Messages SIGMET messages shall be prepared in abbreviated plain language, using approved ICAO abbreviations and numerical values of self-explanatory nature. The format of these advisories consists of a heading and text. The heading identifies the issuing Weather Service Forecast Office (WSFO), type of advisory, and the valid period. The text of the advisory contains a message identifier, a flight precautions statement, and further details if necessary. The period of validity of a SIGMET message should be not more than 6 hours, and preferably not more than 4 hours.
Heading A. ICAO location indicator of the ATS unit serving the FIR or CTA to which the SIGMET refers. Examples: YUDO ZBAA ZSSS. B. Message identification and sequence number. Messages containing SIGMET information for subsonic aircraft shall be identified as "SIGMET", those containing SIGMET information for supersonic aircraft during transonic or supersonic flight shall be identified as "S1GMET SST". Separate series of sequence numbers shall be used for "SIGMET" and "SIGMET SST'' messages. Examples: SIGMET 5, SIGMET SST 1. C. Date-time groups indicating the period of validity in UTC. Examples: VALID 221215/221600. D. Location indicator ofMWO originating the message with a separating hyphen. Examples: YUDO - ,
ZGGG-
Heading examples: YUDD SIGMET 2 VALID 101200/101600 YUSO 302
ZUUU SIGMET3 VALID 101345/101600 ZUGH-
Text A Name of the FIR/ CTA for which the SIGMET is issued or aircraft radiotelephony call sign. Examples: AMSWELL FIR, SHANLON FIRIUIR. AMSWELL FIR/2 B. Detailed content. Description of phenomenon causing the issuance of SIGMET. (see a),b)) C. Indication whether the information is observed (OBS) and expected to continue, or forecast (FCST). Examples: OBS AT 2245Z. D. Location (referring to latitude and longitude (in degrees and minutes) or locations or geographic features well known internationally) Examples: S OF N54, N OF NSO, N2020 W07005 E. Flight level and extent. Examples: FL180, CB TOPFL390.
F. Movement or expected movement with reference to one of the eight points of compass, or stationary. Examples: MOVE 40KMH, STNR G. Expected changes in intensity, INTSF or WKN or NC. INTSF -Intensify
WKN
-Weaken
NC
-No change
H. Forecast position of volcanic ash cloud or the center of the TC at the end of the validity period of the SIGMET message Examples: - FCST 2200Z TC CENTRE N2740 W07345 -FCST 1700Z VA CLD SIS E075 TO S15 E081 TO S17 E083
L Outlook providing information beyond the period of validity of the trajectory of the volcanic ash cloud and positions f the tropical cyclone center Examples: -
OTLK 260400 TC CENTRE N28030 W07430 261000 TC CENTRE N31 00 W07600
-OTLK 212300 VA CLD APRX S16 E078 TO S17 E084 TO S18E089 TO 819 E081 TO S16 E078 220300 VA CLD PRX S 17 E81 TO Sl8 E86 TO S20 E92 TO S21 E84 TO Sl7 E81.
Example ofSJGMET Message YUCC SIGMET 5 VALID 221215/221600 YUDOAMSWELL FIR SEV TURB OBS AT 121 OZ YUSB FL250 MOVE 40KMH WKN Meaning: 303
The fifth SIGMET message issued for the AMSWELL• flight information region (identified in abbreviated plain language and by YUCC Amswell area control center) by the Donlon/ International• meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 UTC to 1600 UTC on the 22nd of the month; severe turbulence was observed at 1210 UTC over Siby/Bistock" aerodrome (YUSB) at flight level 250; the turbulence is expected to move eastwards at 40 kilometres per hour and to weaken in intensity.
Airmen's Meteorological Information (AIRMET)
AIRMET Information AIRMET information shall be issued by a meteorological watch office in accordance with regional air navigation agreement, taking into account the density of air traffic operating below flight level 100. AIRMET information shall give a concise description in abbreviated plain language concerning the occurrence and/or expected occurrence of specified en-route weather phenomena, which have not been included in the area forecast and may affect the safety of low-level flights, and of the development of those phenomena in time and space. The format of the AIRMET is the same as the SIGMET. At cruising levels below flight level 100 (or below flight level 150 in mountainous areas, or higher, where necessary): surface wind speed -
widespread mean surface wind speed above 60 kmJh (30 kt). SFC WSPD (+wind speed and units)
surface visibility -
widespread areas affected by reduction of visibility to less than 5 000 m, including the weather phenomenon causing the reduction of visibility. SFC VIS(+ visibility) (+ weather phenomenon)
thunderstorms -
isolated thunderstorms without hail
ISOLTS
-
occasional thunderstorms without hail
OCNLTS
-
isolated thunderstorms with hail
ISOLTSGR
-occasional thunderstorms with hail
OCNLTSGR
mountain obscuration -
mountains obscured
MTOBSC
cloud information -widespread areas of broken or overcast cloud with height of base less than 300m (1 000
ft) above ground level: -
broken
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BKN CLD (+height of the base and top and units)
-overcast
OVC CLD (+height of the base and top and units)
cumulonimbus clouds which are: -isolated
!SOL CB
-occasional
OCNL CB
-frequent
FRQ CB
towering cumulus clouds which are: -isolated
ISOL TCU
-occasional
OCNLTCU
-frequent
FRQTCU
icing -moderate icing (except for icing in convective clouds)
MOD ICE
turbulence -moderate turbulence (except for turbulence in convective clouds)
MOD TURB
mountain wave -moderate mountain wave
MODMTW
Example ofAIRMET Message YUCC AIRMET 2 VALID 221215/221600 YUDOAMSWELL FIR MOD MTW OBS AT 1205Z AND FCST N48 ElO FL080 STNR NC Meaning: The second AIRMET message issued for the AMSWELL• flight information region (identified in abbreviated plain language and by YUCC Amswell area control centre) by the Donlon!Intemational• meteorological watch office (YUDO) since 0001 UTC; the message is valid from 1215 UTC to 1600 UTC on the 22nd of the month; moderate mountain wave was observed at 1205 UTC at 48 degrees north and 10 degrees east at flight level 080; the mountain wave is expected to remain stationary and not to undergo any changes in intensity.
PILOT WEATHER REPORT A pilot weather report (PIREP) is often the most timely source of information about such weather conditions as icing and multiple cloud layers. While area forecasts and freezing level charts
can give the pilot a good idea of the potential for icing, only a PIREP can let the pilot know what is happening currently.
The Kind of the Plane Report According to the stipulations of International Civil Aviation's Organization, The following aircraft observations shall be made: A. routine aircraft observations and reports during en-route. • Fictitious locations
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B. special aircraft observations and report. C. the aircraft observations and reports during climb-out phases of the flight Aircraft observations shall be reported during flight at the time the observation is made or as soon thereafter as is practicable.
Routine Aircraft Observations and Reports Routine aircraft observations and report are made at the meteorological service report point in the regular flight It produces automatically from the report system of the plane in flight or report by the pilots. The place that must carry on routine observing and report is:
A. at which the applicable air traffic services procedures require routine position reports; and B. which are those separated by distances corresponding most closely to intervals of one hour of flying time. When voice communications are used, in the following situations, an aircraft shall be exempted from making the routine observations: C. the aircraft is not equipped with RNAV equipment; or D. the flight duration is 2 hours or less; or E. the aircraft is at a distance equivalent to less than one hour of flying time from the next intended point oflanding; or F. the altitude of the flight path is below 1 500 m (5 000 ft).
Special Aircraft Observations and Reports The special aircraft observations and report refers to the report to the special weather phenomenon. Special observations shall be made by all aircraft whenever the following conditions are encountered or observed: A. Severe turbulence; or severe icing; or severe mountain wave; B. Thunderstorms, without hail, that are obscured, embedded, widespread or in squall Jines; or thunderstorms, with hail, that are obscured, embedded, widespread or in squall lines; C. Heavy duststorm or heavy sandstorm; D. Volcanic ash cloud; or pre-eruption volcanic activity or a volcanic eruption.
In addition, in the case of transonic and supersonic flights, the special observations shall be made: moderate turbulence; or hail; or cumulonimbus clouds.
The Aircraft Observations and Reports During Climb-out Phases ofthe Flight When other meteorological conditions not listed under (2), e.g. wind shear, are encountered and which, in the opinion of the pilot-in-command, may affect the safety or markedly affect the efficiency of other aircraft operations, the pilot-in-command shall advise the appropriate air traffic services unit as soon as practicable. .When reporting aircraft observations of wind shear encountered during the climb-out and approach phases of flight, the aircraft type should be included. Where wind shear conditions in the climb-out or approach phases of flight were reported or forecast but not encountered, the
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pilot-in-command should advise the appropriate air traffic services unit as soon as practicable unless the pilot-in-command is aware that the appropriate air traffic services unit has already been so advised by a preceding aircraft.
Content of Air-reports When voice communications are used, the elements contained in routine and special air-reports shall be:
Routine Air-reports Message type designator
Section 1. Position information Aircraft identification;
Position or latitude and longitude;
(1)
(2)
Flight level or altitude;
Next position and time over;
(4)
Time
(3) Ensuing significant point
(5)
(6)
Section 2.0perational information Estimated time of arrival;
Endurance
(7)
(8)
Section 3. Meteorological information Air temperature;
Wind direction;
Wind speed; Turbulence
Aircraft icing; Humidity (if available)
Special Air-reports Message type designator
Section 1. Position information Aircraft identification; Position or latitude and longitude; Time; Flight level or altitude;
(1)
(2)
(3)
(4)
Section 3. Meteorological information Condition prompting the issuance of a special air-report, to be selected from the list presented under (2). A PIREP is transmitted in a prescribed format (see Figure 8-50). Required elements for all PIREPs are type of repot, location, time, flight level, aircraft type, and at least one weather element encountered. When not required, elements without reported data are omitted. All altitude references are mean sea level (MSL) unless otherwise noted. Distance for visibility is in statute miles and all other distances are in nautical moles. Time is in universal coordinated time (UTC).
Encoding PIREPs UUAIUA - Type of repot: URGENT (UUA)- Any PIREP that contains any of the following weather phenomena: Tornadoes, funnel clouds, or waterspouts; 307
Severe or extreme turbulence, including clear air turbulence (CAT); Severe icing; Hail; Volcanic ash; Low-level wind shear (LLWS): (Pilot reports air speed fluctuations of 10 notes or more within 2 000 feet of the surface); Any other weather phenomena reported which are considered by the controller to be hazardous, or potentially hazardous to flight operations. UUAIUA
Type or repot
UUAIUA
Type of repot
ov
Location
TA
Temperature
TM
Time
wv
Wind
FL
AJtitude /flight level
TB
Turbulence
TP
Aircraft type
IC
Icing
SK
Sky cover
RM
Remarks
wx
Flight visibility and weather Figure 8-SO PIREP Format
ROUTING (UA) - Any PIREP that contains weather phenomena not listed above, including
low-level wind shear reports with air speed fluctuations ofless than 10 knots. /OV- Location: Use VHF NAVAID (s) or an airport using the three- or four-letter location identifier. Position can be over a site, at some location relative to a site, or along a route. Ex: /OV ZGGG; /OV ZBAA 090025; /OV ZUGH 18010- SUUU; /OVZGGG-SGHK ffM-Time: Four digits in UTC. Ex: !fM1015 IFL- Altitude /flight level: Tree digits for hundreds of feet with no space between FL and altitude, If not known, use UNKN. Ex: FL095; FL310; FL UNKN. rrP- Aircraft type: Four digits maximum; if not known, use UNKN. Ex: !fP L329; !fP B737; ITP UNKN /SK- Sky cover: Describes cloud amount, height of cloud bases, and height of cloud topes. If unknown, use UNKN. Ex: /SK SCT040- TOP080; /SK BKN UNKN- TP0075; /SK BKN- OVC050- TOP UNKN; /SK SKC; 308
IWX- Flight visibility and weather: Flight visibility (FV) reported first in standard METAR weather symbols. Intensity ( - for light, no qualifier for moderate, and + for heavy ) shall be coded for all precipitation types except ice crystal and hail. Ex: /WX FV05SM -RA; /WX FV I ,200M SN BR; /WX RA ffA- Temperature (Celsius):
If below zero, prefix with an "M!' Temperature shall also be reported if icing is reported.
Ex: trA 15; trA M06. IWV-Wind: Direction from which the wind is blowing coded in tens of degrees using three digits. Directions of less than 100 degrees shall be preceded by a zero. The wind speed shall be entered as a two- or three-digit group immediately following the direction, coded in whole knots using the hundreds, tens, and units digits. Ex: IWV 25042KT; IWV 32011 OKT. ITB- Turbulence:
Use standard contractions for intensity and type (CAT or CHOP when appropriate). Include altitude only if different from FL (see Figure 8-50). Ex: trB EXIRM; trB OCNL LGT-MOD BLW090; trB MOD-SEV CHOP 080-110. /IC-Icing: Describe using standard intensity and type contractions. Include altitude only if different from FL(see Figure 8-51). Ex: /IC LGT-MOD RIME; /IC SEV CLR 028-045. IRM- Remarks:
Use free form to clarify the report putting hazardous element first Ex: IRM LLWS-15KT SFC-030 DURC RWY22 TFK. Icing and turbulence reports state intensities using standard terminology when possible. To lessen the chance of misinterpretation, report icing and· turbulence in standard terminology. If a PIREP stated, " .. .PRETIY ROUGH AT 6 500, SMOOTH AT 8,500 PA 24... ," there could be many interpretations of the turbulence at 6 500 feet. A report of "light," or "severe" turbulence at 6 500 feet would have been more concise and understandable. If a pilot's description of an icing or turbulence encounter cannot readily be translated into standard terminology, the pilot's description should be transmitted verbatim. 1) Turbulence Figure 8-51 classifies each turbulence intensity according to its effect on aircraft control, structural integrity, and articles and occupants within the aircraft. Pilots should report location(s), time (UTC), altitude, aircraft type, whether in or near clouds, intensity, and when applicable, type (CHOP/clear air turbulence [CA11), and duration of turbulence. Duration may be based on the time the pilot is flying between two locations or over a single location. 309
Intensity
Aircraft Reaction
Reaction Inside Aircraft
Light
Turbulence that momentarily causes slight, erratic changes In altitude and/or attitude (pitch, roll, yaw). Report as light turbulence or light CAT. or Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude. Report as light CHOP.
Occupants may feel a slight strain against belts or shoulder straps. Unsecured objects may be displaced slightly. Food service may be conducted and little or no difficulty is encountered in walking.
Moderate
Turbulence that causes changes in altitude and/or attitude occurs but the aircraft remains In positive control at all times. It usually causes variations in indicated airspeed. Report as moderate turbulence or moderate CAT. or
Occupants feel definite strains against seat belts or shoulder straps. Unsecured objects are dislodged. Turbulence that is similar to light CHOP but of Food service and walking are greater intensity. It causes rapid bumps or jolts difficult. without appreciable changes in aircraft or attitude. Report as moderate CHOP.
Severe Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control Report as severe turbulence or severe CAT.
Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food severe and walking are impossible.
Extreme Turbulence in which the aircraft i.n violently tossed about and is practically impossible to control. It may cause structural damage. Report as extreme turbulence or extreme CAT. Figure 8-51 Turbulence Reporting Criteria
High-level turbulence (normally above 15 000 feet above ground level [AGL]) that is not associated with cumuliform clouds (including thunderstorms) shall be reported as CAT. 2) Icing Figure 8-52 classifies each icing intensity according to its operational effects on aircraft. Pilots should report location(s), time (UTC), altitude, aircraft type, temperature, and icing intensity and type (rime, clear, or mixed). Rime ice is rough, milky, opaque ice formed by the instantaneous freezing of small supercooled water droplets. Clear ice is a glossy, clear, or translucent ice formed by the relatively slow freezing of large supercooled water droplets. Mixed ice is a combination of rime and clear ice. 310
Intensity
Airframe Ice Accumulation
Pilot Report
Trace
Ice becomes perceptible. Rate of accumulation slightly greater than rate sublimation. It is not hazardous even though deicing/anti-icing equipment is not used unless encountered for an extended period of time (over 1 hour).
Location, time altitude!FL, aircraft type, temperature, and icing intensity and type
Light
The rate of accumulation may create a problem if Location, time altitude!FL, flight is prolonged in this environment (over 1 hour). aircraft type, temperature, and Occasional use of deicing/anti-icing equipment removes/ icing intensity and type prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used.
Moderate
The rate of accumulation is such that even short Location, time altitude!FL, encounters become potentially hazardous and use of aircraft type, temperature, and deicing/anti-icing equipment or diversion is necessary. icing intensity and type
Severe
The rate of accumulation is such that deicing/antiicing equipment fails to reduce or control the hazard. Immediate diversion is necessary.
Location, time altitude!FL, aircraft type, temperature, and icing intensity and type
Figure 8-52 Icing Intensities, Airframe Ice Accumulation, and Pilot Report
Examples and Explanations 1) FTW UA /OV DFW 18005 !fM1803 /FL095 !fP PA 30 /SK 036 OVC 060 /070 OVC 075 /OVCABV The translation is: FTW / UA PIREP from reporting station FfW location is the DFW 180 radial at 5 miles. OVDFW 18005 TM1803 time of the report is 1803. FL095 altitude is 9 500 feet TPPA30 Type of aircraft is a PA 30. SK 036 OVC 060 0700VC075 OVCABV Sky condition: The base of an overcast layer is at 3 600 feet with top at 6 000 feet A second overcast layer has its base at 7 000 feet and its top is 7 500 feet. There is another overcast layer above the aircraft's altitude of9 500 feet. 2) UA/OV KOKC 090064 !fM 1522/FLOSO !fP C172 /SK SCT090-TOP UNKN /WX FVOSSM HZ/I'AM04 /WV 24540KT ITB LGTIRM IN CLR. This PIERP is decoded as follows: UA, 64 nautical miles east of Oklahoma City VOR at 1522UTC, flight levelS, 000 feet MSL. Type of aircraft is a Cessna 172. There is a scattered cloud layer with bases at 9, 000 feet MSL and unknown tops. Flight visibility is restricted to 5 statute miles due to haze. Outside air temperature is -4 degrees Celsius, wind is 245 degrees at 40 knots, 311
light turbulence, and the aircraft is in clear skies. 3) UUA/OV ORD !1M 1235 /FL UNKN trP B727 !fB MOD IRM LLWS +/- 20KT BLW 003 DURD RWY27L. Urgent UA over Chicago 0 Hare Airport, Chicago, IL, at 1235Z. Flight level is unknown but the information is from a Boeing 727. Turbulence was moderate and on decent to runway 27 left, low-level wind shear was detected below 300 feet Airspeed fluctuations were plus and minus 20 knots.
OBSERVATIONS AND REPORTS OF VOLCANIC ACTIVITY The occurrence of pre-eruption volcanic activity, volcanic eruptions and volcanic ash cloud should be reported without delay to the associated air traffic services unit, aeronautical information services unit and meteorological watch office. The report should be made in the form of a volcanic activity report comprising the following information in the order indicated: A. message type, VOLCANIC ACTIVITY REPORT; B. station identifier, location indicator or name of station; C. date/time of message; D. location of volcano and name ifknown; and E. concise description of event including, as appropriate, level of intensity of volcanic activity, occurrence of an eruption and its date and time and the existence of a volcanic ash cloud in the area together with direction of ash cloud movement and height Note -Pre-eruption volcanic activity in this context means unusual and/or increasing volcanic activity which could presage a volcanic eruption. Example: Volcanic activity report VOLCANIC ACTIVITY REPORT YUSB• 231500 MT TROJEEN" VOLCANO N5605 W12652 ERUPTED 231445 LARGE ASH CLOUD EXTENDING TO APPROX 30000 FEET MOVINGSW Meaning: Volcanic activity report issued by Siby/Bistock meteorological station at 1500 UTC on the 23rd of the month. Mt Trojeen volcano 56 degrees 5 minutes north 126 degrees 52 minutes west erupted at 1445 UTC on the 23rd; a large ash cloud was observed extending to approximately 30 000 feet and moving in a south-westerly direction.
AERODROME WARNINGS Aerodrome warnings shall give concise information, in plain language, of meteorological conditions which could adversely affect aircraft on the ground, including parked aircraft, and the aerodrome facilities and services. The warnings shall be issued in accordance with local • Fictitious locations
312
arrangements to operators, aerodrome services and to others concerned, by the meteorological office designated to provide service for that aerodrome. Aerodrome warnings should relate to the occurrence or expected occWTence of one or more of the following phenomena: • tropical cyclone • thunderstorm • hail • snow • freezing precipitation
• hoar frost or rime • sandstorm • duststorm • rising sand or dust • strong surface wind and gusts
• squall • frost
WIND SHEAR WARNINGS Wind shear warnings shall give concise information of the observed or expected existence of wind shear which could adversely affect aircraft on the approach path or take-off path or during circling approach between runway level and 500 m (1 600 ft) above that level and aircraft on the runway during the landing roll or take-off run. Where local topography has been shown to produce significant wind shears at heights in excess of 500 m (1 600 ft) above runway level, then 500 m (1 600 ft) shall not be considered restrictive. Wind shear conditions are normally associated with the following phenomena: • Thunderstorms, microbursts, funnel cloud (tornado or waterspout), and gust fronts •. Frontal surfaces • Strong surface winds coupled with local topography • Sea breeze fronts • Mountain waves (including low-level rotors in the tetminal area) • Low-level temperature inversions. Evidence of the existence of wind shear should be derived from: A. Ground-based wind shear remote-sensing equipment, for example, Doppler radar; B. Ground-based wind shear detection equipment, for example, a system of surface wind and/or pressure sensors located in an array monitoring a specific runway or runways and associated approach and departure paths; C. Aircraft observations during the climb-out or approach phases of flight. 313
D. Other meteorological information, for example, from appropriate sensors located on existing masts or towers in the vicinity of the aerodrome or nearby areas of high ground. Wind shear warnings should be prepared in abbreviated plain language. Wind shear in the approach area should be reported.
Example 1 "WS WRNG SURFACE WIND 320/20KMH WIND AT 60M 360/SOK.MH IN APCH". "WS WRNG SURFACE WIND 320/lOKT WIND AT 60M 360/25KT IN APCH" . Where microbursts are observed, reported by pilots or detected by ground-based wind shear detection or remote-sensing equipment, the wind shear warning should include a specific reference to microburst. Example2 "WS WRNG MBST APCH RWY 26". Where information from ground-based wind shear detection or remote-sensing equipment is used to prepare a wind shear warning, the warning should, if practicable, relate to specific sections of the runway and distances along the approach path or take-off path as agreed between the meteorological authority, the appropriate A TS authority and the operators concerned. Example3 "WS WRNG 30KT AIRSPEED LOSS 2NM FINAL RWY 13" or ''WS WRNG 60KMH AIRSPEED LOSS 4KMFINAL RWY 13". When an aircraft report is used to prepare a wind shear warning, or to confirm a warning previously issued, the corresponding aircraft report, including the aircraft type, should be given unchanged in the warning.
Eumple4 "WS WRNG B747 REPORTED MOD WS IN APCH RWY 34 AT 1510".
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APPENDIX
Figure 1 Cirrus
Figure 2 Cirrocumulus Figure 3 Cirrostratus
Figure 4 Altocumulus
Figure 5 Altostratus
Figure 6 Standing Lenticular Altocumulus Clouds
Figure 7 Nimbostratus
Figure 8 Stratus
Figure 9 Stratocumulus
Figure 10 Cumulus
Figure 11 Towering Cumulus
Figure 12 Cumulonimbus
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