MultiScan Threat Track Operator Guide

operator’s guide Rockwell Collins MultiScan ThreatTrackTM Radar   A318, A319, A320, A321, A330

DRAFT Notice INFORMATION SUBJECT TO EXPORT CONTROL LAWS The technical data in this document (or file) is controlled for export under the Export Administration Regulations (EAR). 15 CFR Parts 730-774. Violations of these laws may be subject to fines and penalties under the Export  Administration Act.

2014 Rockwell Collins. All rights reserved.

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Table of Cont Contents ents 1.0 Introduction ................. ................................... .............................. ......................................... .........................................7 ............7 1.1 Purpose ................. ................................... ................................... ................................... ........................... .................. .........7 7 1.1.1 Keep Passengers and Crew Members Safe .......................7 1.1.2 Enable Ef ficient Aircraft Operation ..................................... .....................................7 7 1.1.3 Lower Operating Risks ................. ................................... .............................. ....................8 ........8 1.2 MultiScan Overview .................. ................................ ......................................... .....................................9 ..........9 1.2.1 MultiScanTM ................ .......................... .............. ........ .................. ..................... .........................9 ..................9 1.2.2 MultiScan V1 ................. .......................................... .............................. ......... ................ .................10 .....10 1.2.3 MultiScan ThreatT ThreatTrack rack ......................................... ........................................... ............1 ..........11 1 1.2.4 Automatic Functions Available in Different Modes ....... ........... ....12 12 2.0 Controls ................. ................................... .................................... ................................... ................................... ......................13 ....13 2.1 General Controls .......................................................................13 2.1.1 MAN/AUTO .................. .......................... ........... ................................ .........................................13 ............13 2.1.2 GCS (Ground Clutter Suppression) OFF/ON ...................15 2.1.3 SYS (SYSTEM) 1/OFF/2 .................. .................................... ................................15 ..............15 2.1.4 PWS (Predictive Windshear) OFF/AUTO ........................15 2.2 Mode Controls ................ ................................. ................................... .................................... .........................15 .......15 ........... ......... .................. ................... ...........................15 2.2.1 WX (Weather) ...... .......... 2.2.2 WX+T (Weather + Turbulence) ........ .......... ...............................17 2.2.3 WX+T+HZD (Weather + Turbulence + Hazard) .............. 17 2.2.4 MAP ................ .................................. .................................................................18 2.3 Tilt Control .............................. .................................. ................................... ...................................1 .................18 8 2.4 Gain Control .. .......................... ................................... ................................... .................................1 ................18 8 2.5 Recommended Operating Mode ................................................18 3.0 Displays (Displayed Information) . ....................................................20 3.1 Gain - Standard Radar Colors/ Reflectivity Rates ......................20 3.1.1 Gain (MAN Operation) .....................................................20 3.1.2 Gain (AUTO Operation) ...................................................22 3.2 Quiet, Dark Cockpit .............................. ................................. .................................... ....................24 ..24 3.3 MultiScan ThreatT ThreatTrack rack ..............................................................25 3.3.1 Directly Detected Threats ................ ........................ ............ .................... .....................26 .....26 3.3.1.1 Core Threat AnalysisTM ................ .............................. ............................2 ..............26 6 3.3.1.2 Predictive OverFlightTM ............................................26 3.3.1.3 Two-Level Enhanced Turbulence .. ..........................27 3.3.2 Associated (Inferred) Threats - Hail/Lightning Prediction .28 3.3.2.1 Mid Altitude Associated Threat ................................ ................................28 28 3

3.3.2.2 Mature Cell Associated Threat ................................29 3.3.2.3 Anvil Top Associated Threat ....................................30 3.4 Attenuation .................................................................................31 3.4.1 Attenuation and Display of Long Range Weather ... .........31 3.4.2 Sensitivity Time Control ....................................................32 3.4.3 “Radar Shadow” ...................... .........................................33 3.4.4 Path Attenuation Compensation (PAC) and PAC Alert .....34 3.5 Beam Width and Cell Height Resolution ... ................................35 3.6 Predictive Windshear (PWS) .....................................................36 3.6.1 Windshear Detection Regions ..........................................37 4.0 Radar Interpretation .........................................................................38 4.1 What Does Green Mean? ..........................................................38 4.1.1 Manual Operating Techniques and the Color Green ........38 4.1.2 Increased Gain at Cruise Altitudes ...................................39 4.2 What Does Green Mean?, Low Altitude Operations ..................40 4.2.1 Stratiform Rain .................................................................40 4.2.2 Bright Band ......................................................................40 4.3 Radar Interpretation, High Altitude Ice Crystals (HAIC) .............42 4.4 Radar Interpretation, Navigable/Non-Navigable Weather .........43 4.4.1 Introduction .....................................................................43 4.4.2 Navigable Weather ..........................................................43 4.4.3 Non-Navigable Weather ..................................................45 4.4.4 Non-Re flective Weather ..................................................46 4.5 Radar Interpretation, Oceanic Weather .....................................47 5.0 How the (MultiScan ThreatTrack) Radar Works ...............................49 5.1 Primary Technologies .................................................................49 5.1.1 Flight Path Hazard Analysis .............................................49 5.1.2 Beam to Beam Power Comparison ..................................50 5.1.2.1 The Challenge .........................................................50 5.1.2.2 Ground Clutter Elimination ......................................51 5.1.2.3 The Quiet, Dark Cockpit ..........................................52 5.1.3 Automatic Temperature Based Gain ... .............................53 5.1.4 Geographic Weather Correlation TM ..................................53 5.1.4.1 Worldwide Weather Variation ....... ...........................53 5.1.4.2 Geographic Weather Correlation Technology .........56 5.1.4.3 Low Lying Stratiform Weather Anomalies ...............57 5.1.5 Track While Scan Analysis ...............................................58 5.1.5.1 Why Threat Analysis? .............................................58 5.1.5.2 Track While Scan Technology .................................58 4

5.1.5.3 Individual Cell Analysis ............................................58 5.1.5.4 Cell Life Cycle .........................................................58 5.2 Secondary Technologies ............................................................60 5.2.1 OverFlightTM Protection ....................................................60 5.2.2 SmartScanTM ....................................................................61 5.2.3 TrueZeroTM .......................................................................62 5.2.4 Radar Scan and Tilt Philosophy .......................................62 6.0 Manual Operating Techniques .........................................................63 6.1 Tilt Control ..................................................................................63 6.1.1 Low Altitude Tilt Control (Below 10,000 ft.) ......................64 6.1.1.1 Initial Climb Out ......................................................64 6.1.1.2 Descent Below 10,000 ft. ........................................64 6.1.2 Mid Altitude Tilt Control (10,000 - 25,000 ft.) ...................65 6.1.2.1 Tilt Technique, 40 and 80 NM Range Scales ..........65 6.1.2.2 Tilt Technique, 160 NM Range Scale ......................66 6.1.3 High Altitude Tilt Control ..................................................67 6.1.3.2 Over Scanning ........................................................67 6.1.3.3 Over Scanning Prevention Methods .......................68 6.1.3.3.1 Method 1 - 80 NM Tactical Range Scale ......68 6.1.3.3.2 Method 2 - 40 NM Over Flight Protection .....68 6.1.3.3.3 Method 3 - MAN MAX Gain ..........................69 6.1.4 Tilt Settings When Descending from High Altitude ... ........70 6.1.5 Oceanic Tilt Settings ........................................................70 6.2 Long Range Weather Detection ................................................71 6.3 Recommended Manual Operating Procedures ..........................72 7.0 Notes ...............................................................................................73 7.1 Manual Notes .............................................................................73 7.2 Radiation Hazard .......................................................................74 7.3 Spoking ......................................................................................74 7.4 V1 Differences ...........................................................................77 7.4.1 Blooming ..........................................................................77 7.4.2 Manual Operation at Top of Descent ...............................78 7.4.3 ThreatTrack Features ......................................................78

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1.0 Introduction 1.1 Purpose: Rockwell Collins’ MultiScan ThreatTrack Radar utilizes multiple innovations that combine the latest in weather research with radar technology in order to accomplish three primary tasks:

1. Keep passengers and crew members safe. 2. Allow flight crews to operate the aircraft ef ficiently. 3. Lower operating risks. 1.1.1 Keep Passengers and Crew Members Safe: Rockwell Collins’ MultiScan ThreatTrack Radar incorporates multiple new technologies (described later in this manual) to decrease the likelihood of unexpected turbulence encounters. The radar eliminates ground clutter, displays threat weather out to 320 NM, estimates and displays actual cell tops, examines the characteristics of the cells to determine their relative threat, predicts growing/mature thunderstorm related turbulence, and provides a two level enhanced turbulence display.

Furthermore, MultiScan’s Quiet, Dark Cockpit philosophy shows flight crews all threats at a glance without having to manipulate the radar’s controls. This reduces pilot workload, reduces cockpit distractions and enables a safer flight. Finally, MultiScan incorporates basic safety functions that have been standard in Rockwell Collins radars for almost two decades; windshear detection and attenuation alert. 1.1.2 Enable Ef fi c ient Aircraft Operation : MultiScan ThreatTrack Radar utilizes the Quiet, Dark, Cockpit philosophy and extended range storm top measurement to enable ef ficient aircraft operations.

The Quiet, Dark Cockpit philosophy means that, when the radar is used in AUTO, only threat weather is displayed. Weather that is beneath the aircraft altitude is not displayed. A recent OEM HMI (Human Machine Interface) study shows the operational ef ficiencies achieved through this philosophy. Note that in the lab when the pilot sample was presented with a MultiScan like HMI, very ef ficient flight operations were achieved. 7

 Almost all pilots navigated the weather in the same manner and did so in a way that saved the most time and fuel. MultiScan Quiet, Dark Cockpit

The Quiet, Dark Cockpit Philosophy results in more ef ficient weather avoidance resulting in less fuel used and more time saved

MultiScan ThreatTrack also incorporates a Beam to Beam Power Comparison technology that enables the radar to begin measuring storm tops at 120 NM with a design goal of accurate storm cell height by 80 NM, which is the distance most pilots prefer for deviation decision making. By way of comparison, “3D” Radars measure cell tops to about half these distances. 1.1.3 Low er Operating Risks : ThreatTrack’s new Associated Threat capabilities reduce the chances of aircraft damage by identifying areas in and around cells that are electrified and have hail potential. The radar performs an analysis of individual thunderstorms and infers the hail and lightning threats associated with the cells based on their intensity and life cycle characteristics.

ThreatTrack  Associated Threat Display

MultiScan ThreatTrack's Assoc iated Threat icon displays a thunderstor m's hail and ligh tning p otential, both in and around t he cell.

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1.2 MultiScan Overview : The generation of new automatic radar’s began in 2000 when engineers at Rockwell Collins invented a method for removing ground clutter returns from the display and automatically displaying weather from the nose of the aircraft out to 320 NM. The resulting MultiScan radar launched in 2002. In 2009 MultiScan V1 introduced the Quiet Dark Cockpit and Geographic Weather Correlation.  And in 2014 MultiScan ThreatTrack provided individual thunderstorm threat analysis (see Section 5, “How the Radar Works”, for details). 1.2.1 Mul tiScan : The original MultiScan Weather Radar launched in September of 2002. The basic/foundational technology uses two radar scans at two different tilt angles to capture all the ground and weather information in front of the aircraft. This information is stored in a temporary memory buffer. An internal terrain table is then used to draw a conformal line above the terrain in front of the aircraft. A Beam to Beam comparison (the heart of MultiScan) is then used to separate the ground clutter from the weather returns. This enables the radar to see all the weather from the nose of the aircraft out to 320 NM.

MultiScan uses two scans at two different tilt angles to capture all the ground and weather information i n front of the aircraft.

 A terrain table that resides inside the radar is used for a number of functions including aiding in ground clutter removal

The ground and weather information is digitized and stored in a temporary memory buffer.

The internal terrain table is used to draw a conformal line above the earth’s surface.  A beam to beam power comparison is then performed, and returns below the line (ground clutter) are removed from the display.

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The end result is the display of the weather from the nose of the aircraft out to 320 NM.

1.2.2 MultiScan V1: MultiScan V1 software was incorporated into the radar in 2009. MultiScan V1 introduced the Quiet, Dark Cockpit concept (i.e. only threat weather is displayed). Using the Beam to Beam Power Comparison technology developed for MultiScan the radar draws a line 6,000 ft. beneath the aircraft. Non-threat weather that is below the line (approximately 6,000 ft. beneath the aircraft) is not shown. Threat weather above the line is displayed on the ND.  A line is drawn six thousand feet beneath the aircraft altitude. A beam to beam power comparison is then performed and only weather above the line is displayed.

 As can be seen below, the HUD (Heads Up Display) indicates that the aircraft will clear the weather seen from the cockpit. Thus, the Quiet, Dark Cockpit concept provides the flight crew with a clean screen which, as studies have shown, will enable the crew to fly the most ef ficient flight path.

Zero Degree Pitch Line

Clean Screen: Non-Threat Wx is not displayed

The HUD’s Zero Degree Pitch Line indicates that the aircraft will clear the weather ahead. Thus, the Quiet, Dark Cockpit concept presents a “clean” screen to the crew.

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The other major technology infusion in MultiScan V1 is the incorporation of Geographic Weather Correlation. Thunderstorm characteristics vary dramatically depending on a cell’s geographic position, whether it is over land or over water and depending on time of year. Geographic Weather Correlation takes all these factors into account to ensure that the actual cell top is displayed on the ND. MultiScan V1 measures the reflective top of the cell and then Geographic Weather Correlation uses storm models to set thresholds that allow the radar to determine whether or not the non-re flective cell top will reach to the aircraft altitude. This significantly reduces the possibility of inadvertent cell top penetration (see section 5, “How the Radar Works”, for details).

Threshold Threshold

Threshold

Mid Latitude Continental Oceanic Equatorial Continental MultiScan V1 incorporates Geographic Weather Correlation technology that enables the radar to account for the signi ficant differences in worldwide thunderstorm characteristics and display non-re flective cell tops on the ND. This significantly reduces the possibility of inadvertent thunderstorm top penetration.

1.2.3 MultiScan ThreatTrack : MultiScan was introduced in 2014 and enables real time threat analysis of individual thunderstorm cells. MultiScan ThreatTrack incorporates a Track While Scan Technology that prioritizes cells and then analyzes over 100 cell characteristics to display the actual convective threat, provide increased awareness of turbulence and predict hail and lightning potential.

Track While Scan Technology enables the radar to track up to 48 thunderstorms while scanning for additional threats

Threats are prioritized and individual vertical analyses performed producing a real time analysis of the cell threats

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Predictive OverFlight: Turbulence from cell growing up beneath the aircraft

Mature Cell Associated Threat: Hail, lightning and turb threats outside the cell boundary

Mid Altitude Associated Threat: Lightning potential in the vicinity of the freezing level FAA Certified (Severe) Turbulence

Ride Quality Turbulence  Anvil Top Associated Threat: Downwind hail threat region

MultiScan ThreatTrack provides analysis tools that facilitate the best possible decision making when transiting severe weather (see sections 2.3.3, 3.3 and 5.1.5 for details)

1.2.4 Aut omatic Funct ion s Availabl e in Different Modes NOTE

Each of the Modes below contains all of the capabilities of the previous mode. For instance, during MAN (Manual) operation only the windshear function is available. But windshear is also available when AUTO + WX and AUTO + WX+T are selected. MAN Selected : Forward Looking Windshear detection only.  AUTO and WX: Forward Looking Windshear plus MultiScan Essential Functions (Ground Clutter Elimination, Extended Range Cell Top Measurement, Automatic Temperature Based Gain, Geographic Weather Correlation, OverFlight ProtectionTM, SmartScanTM, Path Attenuation Compensation (PAC) and Alert, and Quiet, Dark Cockpit).  AUTO and WX+T: All of the above plus Enhanced Turbulence indications out to 40 NM.  AUTO and WX+T and HZD (Hazard): All of the above plus ThreatTrack functions (Track While Scan, Core Threat Analysis, Two Level Enhanced Turbulence, Predictive OverFlight, Mid Altitude Associated Threat, Mature Cell Associated Threat, Anvil Top Associated Threat).

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2.0 Controls

 Ai rbu s Mu lt iScan Thr eatTrac k Co nt ro l Panel

2.1 General Controls 2.1.1 MAN/AUTO: The AUTO switch is a two position switch. Manual is activated when the left-hand MAN position is selected. Automatic operation is selected when the right-hand AUTO position is selected. In the AUTO position the radar controls tilt and gain and analyzes thunderstorm threats to present the best representation of the actual cell threat. NOTE

When AUTO is selected the radar initially displays both weather and ground returns. Three to four sweeps (12 - 16 seconds) are required to remove ground clutter and initialize the automatic functions. Should MAN be selected after initialization is complete, the radar will remember the AUTO settings for two minutes before initialization will again be required.  AUTO: When the radar is in AUTO and WX is selected MultiScan’s essential automatic weather detection features are activated (see page 18 ***).  AUTO and WX+T: When the radar is in AUTO and WX is selected MultiScan’s essential automatic weather detection features are activated and Enhanced Turbulence returns are displayed out to 40 NM (see page 15).  AUTO and WX+T+HZD (Hazard); When AUTO and WX+T+HZD are selected, MultiScan’s essential features, Enhanced Turbulence, and ThreatTrack features are activated (see page 17).  AUTO and WX+T+HZD are recommend ed durin g all phases o f fl ight .

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When AUTO is selected (MAN/AUTO switc h selected to AUTO) the til t cod e is displayed without any additional indications.

IMPORTANT  AUTO and WX+T+HZD are recommended in all phases of flight.

NOTE During AUTO operation the tilt displayed on the ND is the average of the two scans used to collect ground and weather information (see section 1.2.1 and 5.2.4 for details).

When Manual i s selected (MAN/AUTO switc h selected to MAN), “ MAN” is disp layed in front of the tilt code.

NOTE When toggled to MAN the radar operates like a traditional manual radar. Tilt and gain must be manually controlled (see “Manual Operating Techniques”, section 6.0). With the exception of Windshear, all automatic features are disabled. 14

2.1.2 GCS (Ground Clu tter Supp ression) OFF/ON:  The GCS switch is a spring loaded switch that defaults to the AUTO position (Ground Clutter Suppression Activated). When held in the MAN position all returns (ground clutter and weather) are displayed. Once released, ground clutter will be removed from the display on the next sweep.

NOTE The GCS switch is inactive during MAN operation. 2.1.3 SYS (System) 1/OFF/2 : The left side #1 position selects the left R/T (Receiver Transmitter). The right side #2 position selects the right R/T. Then center OFF position turns the radar off. 2.1.4 PWS (Predi ctive Windshear) OFF/AUTO: When PWS is selected to OFF the Predictive Windshear warning system is deactivated. When the PWS switch is selected to AUTO the Predictive Windshear system is activated and will provide warnings to the flight crew even if the radar is turned off.

WARNING When the PWS switch is selected to OFF Windshear annunciations will not be displayed. It is recommended that the PWS switch be left in the AUTO position at all times. 2.2 Mode Control s 2.2.1 WX (WEATHER) : When the radar is in AUTO and the WX mode is selected MultiScan’s essential automatic weather detection features (explained in detail in Section 5, “How The Radar Works”) are activated. The essential functions include:

1. Ground Clutter Elimination 2. Extended Range Cell Top Measurement 3. Automatic Temperature Based Gain 4. Geographic Weather Correlation 5. OverFlight Protection 6. SmartScan 7. Path Attenuation Compensation (PAC) and Alert 8. Quiet, Dark Cockpit 9. Forward Looking Windshear Detection The pictures on the following page show the end results. MultiScan eliminates the ground clutter and displays the weather out to 320 NM. In addition, MultiScan utilizes the Quiet, Dark cockpit philosophy to display only weather information that is a threat to the aircraft. 15

In these pictures note the absence of ground clutter and the thunderstorm cells at 60, 120, and 200 NM. In addition, the radar displays a fourth cell that is over the horizon at 300 NM.

300 NM  Attenuation (PAC) Alert 200 NM

120 NM

60 NM

300 NM (Over the Horizon) 120 NM

60 NM

200 NM

Quiet, Dark Cockpit: Non-threat weather is not displayed

NOTE Due to the fact that weather changes rapidly and the radar now has an effective range of 320 NM, it is not unusual to see a complete thunderstorm cycle with mature cells dissipating and new cells appearing on the display as the aircraft moves towards the weather. 16

2.2.2 WX+T (Weather + Tur bu lence): When the radar is in AUTO and the WX+T mode is selected MultiScan’s essential automatic weather detection features (see previous section) are activated and Enhanced Doppler Turbulence returns are displayed out to 40 NM on all range scales.. 2.2.3 WX+T+HZD (Weather + Tur bu lence + Hazard): For the new MultiScan ThreatTrack radar WX+T+HZD is a new Mode Control Option that enales the new ThreatTrack software. The ThreatTrack software combines the essential MultiScan functions mentioned in section 2.21 with several new analysis tools and iconic information that enables flight crews to better assess actual thunderstorm threats. ThreatTrack is based on Rockwell Collins’ Track While Scan and Flight Path Hazard  Analysis technologies which are described in detail in Section 5, “How the Radar Works”. WX+T+HZD enables the following new features:

1. Core Threat Analysis, 2. Predictive OverFlight, 3. Two Level Enhanced Turbulence, 4. Mid Altitude Associated Threat Assessment, 5. Mature Cell Associated Threat Assessment, and 6.  Anvil Top Associated Threat Assessment Core Threat  Analysis

Predictive OverFlight

Two Level Enhanced Turbulence

Mid Altitude  Associated Threat

Mature Cell  Associated Threat

 Anvil Top  Associated Threat

ThreatTrack capabilities and display interpretation are discussed in Section 3.3

IMPORTANT During MAN operations ThreatTrack (HZD) functions are not available. WX+T+HZD reverts to the standard WX+T function. 17

2.2.4 MAP: MAP mode enables display of all radar echoes including terrain and weather information. The receiver sensitivity is decreased by approximately one color level to accommodate terrain characteristics instead of weather. This mode enables identification of terrain features such as mountains, coastlines, bodies of water etc.

I-90 I-88 I-55 I-80

Chicago Lake Michigan

MAP Mode displays all radar echoes, terrain and weather 

NOTE When MAP mode is active Turbulence and PAC Alert information are not displayed. NOTE When operating in AUTO and below 10,000’ MAP mode will not display adequate ground returns due to the position of the radar beams. Manual operation of the radar will be required for adequate ground mapping below 10,000’.

2.3 TILT Control : The tilt control is inactive during AUTO operation. MAN TILT operation is discussed in detail in section 6.0, “Manual Operating Techniques”. 2.4 GAIN Control : Calibrated (CAL) gain is selected when the Gain Control deten is selected to the CAL position (see picture next page). Maximum (MAX) gain is achieved when the gain knob is rotated to the fully clockwise MAX Gain position. Minimum (MIN) Gain occurs when the knob is rotated to the fully counter clockwise MIN Gain position.

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CAL Gain (Calibrated Gain)

NOTE The numbers on the Gain Control correlate to the Gain Schedule described in Section 3.1.1.

MIN Gain (Fully Counter Clockwise)

No Gain indication above the tilt The numbers the Gain Control codeon indicates ule described in Section 3.1.1. the radar is in the CAL Gain position .

correlate

MAX Gain (Fully Fu Clockwise)

MAN GAIN indicates that the to theisGain SchedGain set either above or below the CAL Gain position.

NOTE Full above and below the calibrated gain position is available during both MAN and AUTO operation. 2.5 Recom mended Operatin g Mode: The recommended operating mode for MultiScan ThreatTrack is AUTO, CAL Gain, and WX+T+HZD

(Weather Plus Turbulence Plus Hazard) in all phases of flight.

Recommended Settings During All Phases of Flight (Tilt Control Inactive)

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3.0 Displays (Displayed Inform ation) 3.1 Gain - Standard Radar Colors/Refl ectivity Rates : In MAN CAL Gain the radar paints the standard re flectivity rates (representing rain fall rates) for red, yellow, green and black. Weather that is present in the black region is not reflective enough to meet the green threshold display criteria. Notice that an increase or decrease of ten dB of sensitivity represents a change of one color level. Standard Radar Refl ecti vit y (Rain Fall) Rates Less than .76 mm/hr (.03 in/hr)

Weak (20 dBz)

.76 - 3.81 mm/hr (.03 - .15 in/hr)

Moderate .3.81 - 12.7 (30 dBz) mm/hr (.15 - .5 in/hr)

Strong to Very Stro ng (40 dBz and Greater 

10 dBz

10 dBz

12.7 mm/ hr (.5 in/ hr) and Greater 

During MAN operation radar colors are determined by rainfall rates (note: dBz is an engineering term for reflectivity). Note that there is 10 dB of gain between each color level.

3.1.1 GAIN (MAN Operation) : As can be seen in the chart below, increasing the gain to MAX increases the sensitivity by 16 dB or an increase of one and a half color levels. Conversely, selecting Minimum gain decreases the sensitivity by 14 dB and reduces the color levels approximately one and half times.

Gain Table: WX, WX+T, WX+T+HZD Modes Control Position

Gain Change

ND Indication

Fully CW

+16 dB

MAN GAIN

+12 dB

MAN GAIN

+8 dB

MAN GAIN

+4 dB

MAN GAIN

CAL

Fully CCW

+0 dB -3 dB

MAN GAIN

-6 dB

MAN GAIN

-9 dB

MAN GAIN

-12 dB

MAN GAIN

-14 dB

MAN GAIN

Each gain number in the chart is also displayed on the Gain Control knob (see Section 2.4). MAX gain is achieved by turning the knob fully clockwise to the MAX position. MIN gain is achieved by turning the knob fully counterclockwise to the MIN position. Note that +8 position increases the gain by approximately one color level. Conversely, the -9 position decreases gain by about one color level. 20

The pictures below show the changes at various gain setting. MAX (+16 dB)

-3 dB

+12 dB

-6 dB

+8 dB

-9 dB

+4 dB

-12 dB

CAL (+0 dB)

MIN (-14 dB)

WARNING MIN Gain should only be used for momentary weather evaluation. Gain should then be returned to the CAL gain position in order to avoid under representing the thunderstorm threat. 21

3.1.2 Gain (AUTO Operation) : During AUTO operation MultiScan uses an Automatic Temperature Based Gain technology to automatically control gain and help prevent inadvertent thunderstorm top penetration (described in more detail in Section 5.0, “How the Radar Works”).

 A typical thunderstorm is very reflective below the freezing level. However, the top of the storm tends to be glaciated (composed of ice crystals) and non-reflective. As an aircraft climbs the radar beam moves higher in the cell, and, at cruise altitudes, can over scan the re flective portion of the cell resulting in inadvertent thunderstorm top penetration. Glaciated (composed of ice crystals)  As the aircraft climbs the beam can eventually over scan the re flective portion of the cell. This can cause the storm to fall off the display and result in inadvertent cell top penetration.

The mid portion of a cell is composed of a combination of water and ice crystals and is moderately reflective.

The lower portion of a cell beneath the freezing level is completely liquid (rain) and a good radar re flector.

 As the aircraft climbs and the outside air temperature decreases, Automatic Temperature Based Gain automatically increase gain to compensate for the lower reflectivity of upper level thunderstorms. The following pictures illustrate the difference between manual and auto gain at cruise altitudes. Note that at cruise altitudes Manual MAX Gain and Auto CAL Gain present essentially the same picture due to the  Automatic Temperature Based Gain feature that is active during AUTO operation. 22

Thunderstorm as viewed from the cockpit.

MAN CAL

MAN CAL Gain selected. Manual tilt set properly (see section 6.1.2 and 6.1.3)

 AUTO CAL

 AUTO CAL Gain selected. Note that AUTO CAL Gain and Man MAX Gain display essentially the same level of cell intensity.

MAN MAX

MAN MAX Gain selected. Tilt is unchanged from previous picture.

 AUTO MAX

 AUTO MAX Gain selected. Full above CAL Gain control is available in AUTO but will over represent the threat.

Because of Automatic Temperature Based Gain, AUTO CAL gain provides the best representation of the actual threat, best de fines the true extent of the cell and helps prevent inadvertent cell top penetration.  AUTO CAL Gain is recommended in all phases of flight. IMPORTANT  At cruise altitudes MAN Max gain and AUTO CAL gain are essentially equivalent. In AUTO, further increasing the gain above the CAL position may result in over warning and unnecessary deviations. IMPORTANT MultiScan’s use of variable temperature based gain means that most flight crews will see more than they are used to seeing when using the radar in AUTO. Please refer to Section 4.0, “Radar Interpretation” for details. 23

3.2 Quiet, Dark Cockpit : MultiScan uses the Quiet, Dark Cockpit philosophy to display weather threats. If the weather is not a threat (i.e. it is more than approximately 6,000 ft. beneath the aircraft), it is not displayed. In the picture below note the Flight Path Vector on the HUD display and also note that it is intersecting the zero degree pitch line. This clearly shows that the aircraft flight path is above the cells seen by the pilot. As a result, the display shows a clean screen since the weather is below the aircraft flight altitude. Flight Path Vector  Zero Degree Pitch Line

Quiet, Dark Cockpit: This view is through the HUD combiner. The Flight Path Vector (FPV) is indicating acceptable over flight clearance. Weather that is more than approximately 6,000 ft. below the aircraft is NOT displayed.

Quiet, Dark Cockpit

Weather that is below the aircraft altitude is often visible from the cockpit and there are occasions where it may appear that cells should be displayed, but are not. For instance, in the pictures below it is not initially apparent whether or not the cell is at the aircraft altitude.

80 NM

40 NM From a distance this cell appears to be at or near the aircraft altitude.

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 After a cell rains out significant cloud can remain suspended in the atmosphere, but it has little to no convective activity at altitude. On close approach it can be seen that this cell is post convective (you can see right through it). Therefore, applying the Quiet, Dark Cockpit philosophy, this non-threat cell is not displayed.

Quiet, Dark Cockpit

From a distance this cell appears dangerous. However, upon further examination it can be seen that it is post convective and has very little substance. It is also slightly below the aircraft flight path. Therefore, it is not displayed.

IMPORTANT When using the radar in MAN mode it is always possible to adjust the radar to get the picture you believe should be present. In this case it might be possible to see this cell if a very low tilt setting is used to detect rain at lower altitudes. However, in AUTO mode the radar uses extensive weather analysis to display the actual threat.

3.3 MultiScan ThreatTrack : MultiScan ThreatTrack displays both directly detected threat and inferred threat information. Directly detected threats, as the name implies, are direct measurements of observed threats. Inferred (estimated) threats are based on analysis of individual thunderstorms and are derived from the convective nature and life cycle development stage of the cells.

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3.3.1 Directl y Detected Thr eats 3.3.1.1 Core Threat Analysis : A key design feature of MultiScan ThreatTrack makes the colors displayed on the ND more representative of the actual thunderstorm threat. When the Track While Scan technology (see Section 5.1.5) determines that the convective activity is more intense than the precipitation level would normally indicate, Core Threat Analysis increases the color level to better represent the actual threat. Core Threat Off 

Notice that the radar return with Core Threat “On” correlates much more closely with the hazard picture provided by the ground based radar. In cases where the convective activity is already properly displayed colors are left unchanged.

Core Threat On

Ground Radar Composite Hazard Picture

3.3.1.2 Predictive OverFlight : Rapidly growing thunderstorms push a turbulence bow wave above them as they grow that can produce severe turbulence even though the aircraft is several thousand feet above the visible top. Predictive OverFlight uses MultiScan ThreatTrack’s Track While Scan Technology to detect and measure cell growth rate and then predicts the resulting bow wave turbulence created by the storm. The Predictive OverFlight Icon (next page) is used to warn flight crews of the Thunderstorm cells can grow as rapidly as 6,000 ft. per potential turbulence minute. When this occurs a turbulence bow wave is threat from a cell that pushed ahead of the growing cell. is growing towards the aircraft’s flight level.

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Predictive OverFlight icon

The Predictive OverFlight icon warns of bow wave turbulence that is a result of rapidly building cells beneath the aircraft

NOTE Because the cell is growing towards the aircraft altitude weather may eventually appear on the display and replace the Predictive OverFlight icon. NOTE The Predictive OverFlight alert is displayed out to 40 NM. However, Predictive OverFlight alerts may occur much closer to the aircraft based on the growth rate and location of the cell relative to the aircraft.

3.3.1.3 Two-Level Enhanced Turb ulenc e: Two-Level Enhanced Turbulence measures severe and ride quality turbulence out to 40 NM. When the FAA standard for severe turbulence is met (.3g rms) solid magenta is displayed. When the radar detects less severe ride quality turbulence, consisting of light to moderate chop, then speckled magenta is displayed.

Light to Moderate Chop Severe Turbulence

Solid magenta represents the FAA de fined standard for severe turbulence. Speckled magenta represents ride quality turbulence (i.e. light to moderate chop)

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3.3.2 Ass oci ated (Inferred) Threats - Hail and Light nin g Predict ion

NOTE See Section 5.0, “How the Radar Works” for details regarding the engineering and science behind the Associated Threat warnings. 3.3.2.1 Mid Al titude Associated Threat : Towards the end of the cumulous stage of thunderstorm development, cells become electri fied but do not yet have extensive high altitude convective activity. Never the less, these mid altitude cells do contain lightning potential. MultiScan ThreatTrack radar denotes this mid altitude lightning threat by placing red speckles within the cell boundaries.

Electrified Cells

The Mid Altitude Associated Threat denotes cells with lightning potential by placing red speckles within the cell boundaries

NOTE The mid altitude associated threat icon will no longer be displayed once the aircraft climbs more than 10,000 ft. above the freezing level.

 Approximately 80% of lightning strikes occur within plus or minus 3,500 feet of the freezing level. When electrified cells are present maintain an appropriate distance from electrified cells in accordance with company guidelines. When possible, minimize time in the vicinity of the freezing level.

The majority of lightning strikes occur within the vicinity of the freezing level

Freezing Level

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3.3.2.2 Mature Cell Associated Threat : During the mature stage of thunderstorm development strong updrafts carry moisture aloft with the result that there is high re flectivity at cold temperatures. These mature cells create lightning and hail potential and produce very strong turbulence. What is more, because the strong updrafts associated with these thunderstorms can exit the top or sides of the cell the potential threat area can extend well outside the cell boundaries. In the case of a Mature Cell Associated Threat warning, MultiScan ThreatTrack extends the warning area outside the cell boundary to denote the increased threat.

Mature Cell Associated Threat Icon The Mature Cell Associated Threat places red speckles outside the cell boundary to denote hail, lightning and turbulence potential

IMPORTANT Displayed weather returns are directly detected threats. The red speckles represent an inferred or predicted threat. Therefore, when pilots are making deviation decisions, weather should always take priority over the red speckled regions. IMPORTANT The speckled icon represents a region where a threat may be present, but it is not a threat boundary. Turbulence and hail can extend outside the icon boundaries. Conversely, in some cases flight crews may penetrate this region without incident. Turbulence and hail might be present, but at a different altitude. NOTE There will be occasions where the associated threat icon appears suddenly. For rapidly growing cells the transition from the Cumulous stage to the Mature stage can happen in a matter of minutes. When the cell reaches the Mature Cell threshold, the icon is displayed. NOTE The Mature Cell Associated Threat icon is displayed at all altitudes during all phases of flight. 29

3.3.2.3 Anvil Top Associated Thr eat : Mature cells often form an anvil top downwind of the thunderstorm. In these instances hail can be ejected from the top of the cell and create a hail  Anvil Top danger area in downwind region. Above 25,000’ MultiScan ThreatTrack’s Anvil Top Cell  Associated Threat warning uses the upper Core level winds to define a potential region of ejected hail downwind of the cell. The region will be larger or smaller depending on the wind velocity.

o

195 /60

 Anvil Top (Down Wind) Threat Region

The Anvil Top Associated Threat warns of a hail danger region downwind of the cell

NOTE This is another reminder that, whenever possible, it is best to transit thunderstorms to the upwind side. NOTE The downwind threat region is activated when the aircraft climbs above 25,000 ft. and the wind is greater than 10 kt. NOTE Climbing through 25,000 ft. the icon shifts direction to orient along the upper level wind axis and increases the downwind length in direct proportion to the wind velocity.

Below 25,000’

Above 25,000’

 Above the 25,000 ft. the Anvil Top Associated Threat uses upper level wind information to rotate the Mature Cell Icon and extend it downwind into the predicted hail threat region.

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3.4 Attenuation : Significant attenuation of the radar signal due to absorption and scattering occurs as the transmitted pulse moves to its furthest range and again during transit back to the receiver from a radar target. In addition, beyond 80 NM a normal thunderstorm (de fined as a 3 NM sphere of water) no longer fills the radar beam. As a consequence, significant amounts of radar energy bypass the target entirely. The end result is that, for weather targets detected at extended ranges, the signal received back at the aircraft is signi ficantly weaker than the original radar pulse. The radar signal is continuously attenuated with the result that the return signal is significantly weaker than the original transmitted pulse. Transmitted Pulse Return Energy

50 NM

80 NM

300 NM

3.4.1 Attenuation and th e Disp lay of Long Range Weather : At longer ranges due to attenuation the radar will only be able to see very strong weather such as thunderstorm cores. As these storms approach the aircraft more of the cell becomes visible. In the pictures below first note the line of cells at 300 NM. As the cells approach the aircraft attenuation is lessened and the cells appear to grow. Within 80 NM the full extent of the storms becomes visible to the radar. Due to attenuation the radar can only see thunderstorm cores at 320 NM. As cells near the aircraft they will appear to grow. In actuality, attenuation is decreasing and the radar is better able to see the full extent of the cells.

Line of cells at 280 NM

Line of cells at 120 NM

Line of cells at 240 NM

Line of cells at 80 NM

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3.4.2 Sensitivity Time Control (STC) : STC is designed to compensate for beam attenuation of the aircraft by increasing receiver sensitivity over time so that more distant thunderstorm cells have more energy on the target than do cells closer to the aircraft. Sensitivity time control (STC) increases receiver sensitivity over time. As a consequence distant thunderstorm cells have more energy on target than do close in cells.

  y    t    i   v    i    t    i   s   n   e    S   r   e   v    i   e   c   e    R

 S  T   C  L  i   m i    t  

Time (Distance)

 As cells approach the aircraft STC decreases sensitivity to prevent the cells from growing in intensity. However, due the use of increased gain in AUTO (see section 3.1.2), STC limits for green are reached at approximately 40 NM and green (and occasionally some yellow) may appear on the display. For instance, as the pictures below show, A potential transit corridor between two cells is visible at 50 NM. However, due to STC limitations, green returns are visible between the cells at 40 NM. Essentially, at 40 NM the radar displays the haze layer that is between the two cells. Flight crews will experience light to moderate chop when transiting this corridor (see next Section 4.0, Radar Interpretation).  At 50 NM a potential transit corridor can be seen between the cells at the top left of the ND.

STC is unable to compensate at 40 NM and haze layer between the cells is displayed.

Transit Corridor fills with green

Potential Transit Corridor 

IMPORTANT It should be considered normal radar operation when green appears on the display at around 40 NM. In this case, green represents navigable weather and light to moderate chop would be expected. 32

3.4.3 “ Radar Shado w” : When intervening rainfall becomes heavy the radar beam may be so severely attenuated that there is not enough energy to penetrate the weather, see what is behind, and then return to the aircraft. When this situation occurs weather behind the intervening rainfall will be masked. This area of hidden weather is often referred to as an area of radar shadow.

 Attenuated  Area

 Attenuated  Area  Attenuated  Area

 Attenuated  Area

(1) Due to attenuation the cells at 5 NM are masking signi ficant weather behind them.

(2) Upon penetration attenuation increases. Previously visible weather is masked.

(3) At the mid point of the penetration a small weather return is visible behind the storm.

(4) Near the trailing edge of the initial storm cell several additional returns become visible.

Hook

(5) At the trailing edge of the initial cell t he new returns form a new thunderstorm line.

(6) After exiting the true extent of the weather is visible. “Hooks”, such as the one at the cell’s bottom right, have sometimes been associated with tornado activity.

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3.4.4 Path Attenuatio n Compens ation (PAC) and PAC ALERT: Path  Attenuation Compensation compensates for intervening rail fall in order to display more distant cells with the correct intensity. When the rain fall intensity becomes so great that the system can no longer compensate it Alerts the flight crew. The yellow arc on the edge of the outer range scale of the picture below is a PAC Alert and indicates that the radar can not see behind the intervening cell. The area behind the cell (radar shadow) should be avoided since it represents an area where weather information is not being displayed. PAC Alert Bar   Area of  Attenuation (Radar Shadow)

The yellow PAC Alert bar warns flight crews of attenuated regions, (sometimes called a radar shadow) while maintaining the Quiet, Dark Cockpit philosophy.

It takes a signi ficant thunderstorm to attenuate the radar and cause the PAC Alert function to activate. This is the actual cell that is displayed on the ND above.

IMPORTANT PAC and PAC Alert are active only when AUTO and CAL gain are selected and the cell is within 80 NM of the aircraft.  AUTO CAL Gain Selected. PAC Alert is displayed.

ND indicates VAR (CAL Gain not selected). PAC Alert is not displayed.

WARNING Never fly into an attenuated region (radar shadow). Substantial weather threats may be present that are masked by the intervening weather. 34

3.5 Beam Width and Cell Height Resolu tio n: The MultiScan radar utilizes a 3.5 degree beam. And although this may seem pretty narrow, by 80 NM it is already 25,000 ft. in diameter (see picture below). As a result, height estimation of the cell becomes more and more coarse the further it is from the aircraft. Therefore, on occasion, weather that is initially visible at longer ranges may fall off the display as it approaches the aircraft and the radar can better determine the cell height. 3.5o Radar Beam

Center cells indistinct at 240 NM

Center cells appear at aircraft altitude at 170 NM

Radar resolves cell heights closer to aircraft

NOTE The radar sees only large cells at 320 NM. Therefore, cells visible on the ND at 320 NM are normally at the aircraft altitude and will remain on the display until passing behind the aircraft. NOTE Cell top measurement begins at 120 NM with the intent of having accurate deviation information by 80 NM. NOTE  A single cell life cycle is approximately 60 minutes (see Section 5.1.5.4). Therefore, over 320 NM, cells may appear or disappear on the display due to normal cell growth and decay. 35

3.6 Predi ctive Windshear (PWS): Predictive Windshear is activated for all altitudes below 2,300 ft. AGL for both the take off and landing phases of flight when the PWS switch is selected to AUTO. Upon activation the weather scan region decreases to 120 o to enable faster weather and windshear updates. Alerts are displayed in the cockpit below 1,200 ft.

Windshear  Warning Yellow arc “points” to the windshear event (even on range scales that might not display the actual windshear icon)

Windshear Icon (marks actual windshear location)

120o weather scan

This particular windshear occurred during taxi. In these pictures from the cockpit the windshear can be seen in the form of a line squall approaching the aircraft down the taxiway. The pilot delayed his takeoff for 30 minutes until the thunderstorm had passed the airport and departed without incident.

36

3.6.1 Windshear Detecti on Regions : The picture below shows the windshear detection regions for Approach/Go Around and Take Off. A windshear encountered in either the Yellow (Caution) or Red (Warning) region produces an aural and visual alert in the cockpit. If a windshear is detected in the Blue (Advisory) region only a windshear icon is displayed Aircraft Heading

Aircraft Heading

30

30

30

30

5 nm

5 nm

Advisory

3 nm

3 nm Caution

Approach and Go-Around Warning Caution Advisory

 Takeoff Role

Warning

.25 nm

.25 nm

.25 nm

.25 nm

Windshear Detection Regions

Windshear Alert Table

Aural Alert

EFIS Indication

 Advisory

None

Windshear Icon

Caution

“Monitor Radar Display”

Windshear 

Warning (approach)

“Go Around, Windshear Ahead”

Windshear 

Warning (take off)

“Windshear Ahead, Windshear Ahead”

Windshear 

NOTE Even if the radar is turned off, windshear is automatically activated when takeoff speed reaches 35 knots. Aural alerts and cockpit annunciators are operational. NOTE If the radar is on but in MAP or TEST mode and the system detects a windshear event, the system display will automatically change to the WX+T mode to display weather and windshear icons. The selected range does not change automatically. NOTE The radar stores up to three windshear events of twelve sweeps each. If further analysis of a windshear event is required the information can be down loaded with a lap top computer. 37

4.0 Radar Interpretation 4.1 What Does Green Mean? 4.1.1 Manual Operating Techniques and the Color Green : Depending on your manual operating techniques, green may mean very different things to different pilots. As an example, in low reflectivity oceanic environments some flight crews use MAN Max Gain and a low tilt setting and then avoid all weather that paints yellow or red under the assumption that the threat reaches to the aircraft altitude. In these instances when  AUTO paints the cells green, the crews consider the radar to be under warning. Under Warnin g?

Manual Max Gain

 AUTO CAL Gain

Crews whose manual operating techniques include use of MAN Max gain and lower tilt settings may believe that AUTO is under warning.

When crews use MAN CAL Gain and moderate tilt settings in an oceanic environment thunderstorm cores often paint green. Experience has taught these crews that green is a substantial threat and must be avoided. When MultiScan is used in AUTO and paints the core red and then adds substantial areas of yellow and green, some pilots may consider the radar to be over warning.

Over Warnin g?

Manual CAL Gain

 AUTO CAL Gain

Crews who use MAN CAL gain and normal tilt settings may believe that t he radar is over warning when AUTO is selected.

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IMPORTANT The MultiScan algorithms are designed to give a consistent weather picture when using the radar in AUTO. Note, however, that the display will not be the same as when operating in manual. In fact, due to the use of Variable Temperature Based Gain and the Quiet, Dark Cockpit philosophy, it is not possible to get the same picture in MAN that you will see in AUTO.

4.1.2 Increased Gain at Cruise Alt itu de: MultiScan uses variable temperature based gain (see Section 3.1.2) to better detect low reflectivity thunderstorm tops. The series of pictures below is taken over the Gulf of Thailand. Note that in manual mode in calibrated gain very little weather is displayed. When manual max gain is selected, a weather ridge line is visible to the flight crew. Because the Gulf of Thailand is a low reflectivity environment and cells are dif ficult to detect, AUTO CAL gain is actually more sensitive than manual max gain and displays more of the weather system for the crew.

Manual CAL Gain

Manual MAX Gain

 AUTO CAL Gain

MultiScan uses Variable Temperature Based Gain to better detect non-re flective cell tops.  As a result, at cruise altitude AUTO CAL Gain and Manual MAX Gain are similar.

IMPORTANT When using the radar in AUTO most flight crews will see more than they are used to seeing due to the use of Variable Temperature Based Gain (see Section 3.1.2). NOTE During AUTO operation at cruise altitudes, Automatic Temperature Based Gain enables crews to better see the true extent of thunderstorms, pressure ridges, haze layers between cells and potential icing conditions.

39

4.2 Radar Interpr etatio n, Low Altit ude Operatio ns 4.2.1 Stratiform Rain : There are many times where the color green is not a threat and indicates, at most, light to moderate chop. For instance, consider the picture below where the majority of the display is painting green. At lower altitudes this occurs during stratiform rain conditions and only light to moderate chop would be expected.

 At lower altitudes green solid green returns normally represents stratiform rain and, at most, represents light to moderate chop.

4.2.2 Bright B and/Mons oon : There are occasions during certain unique meteorological conditions where the display may turn completely yellow or even red (sometimes called “red out”). Bright Band is associated with stratiform rain or snow and occurs from the freezing level to 3,000 ft. beneath the freezing level. In this region, ice crystals begin to melt and are coated with a layer of water resulting in very strong radar returns. Ground Based Vertical Weather Radar Presentation 7 6

5

    )    m4     k     (    t     h    g     i    e 3     H

Bright Band

2

1

Bright Band produces very strong radar returns that can turn the entire display yellow or red

40

In the picture below, the aircraft is right at the freezing level and melting snow has formed an area of strong re flectivity turning the display yellow even though there is very little turbulence.

Bright Band has caused much of the display to turn yellow.  At longer ranges the display turns green due to the fact that the radar beam is pointed up out of the Bright Band region.

 A similar situation sometimes occurs during monsoon rains where heavy rain fall rates produce very strong re flectivity. In the case of monsoon rains it is not unusual for the entire display to turn red. Should flight crews encounter a red out situation, gain can be temporarily reduced by four clicks, or about one color level (Section 3.1.1), to better determine if embedded cells are hidden by the heavy stratiform rain.

Reducing the gain by about one color level (counter clockwise four clicks) will enable the crew to determine i f strong embedded cells are in the yellow/red region. In this case, embedded cells are not present.

41

4.3 Radar Interpr etatio n, High Alti tud e Ice Crys tals (HAIC): During high altitude operations interpretation of the picture below changes. In this case, a broad area of green may indicate HAIC conditions.

Green returns that fill the radar display are not normal at cruise altitudes and may indicate Ice Crystal Icing conditions.

 As the satellite picture below shows, ice crystals can be present over a broad geographic area. These ice crystal clouds are normally caused by significant amber or red cells beneath the aircraft altitude. Ice Crystal Icing has resulted in T.A.T. anomalies and engine power loss.

TAT Start TAT End

The aircraft transiting this Ice Crystal Icing region experienced T.A.T. anomalies about half way through the ice crystal cloud. The anomalies stopped shortly after exiting.

The aviation industry is engaged in a multi-year research program to better understand how to anticipate and protect against Ice Crystal Icing 42

Conditions. However, initial flight tests conducted by Rockwell Collins and actual incidence reports have shown that, when in AUTO CAL Gain, the radar’s Variable Temperature Based Gain function often displays these ice crystal clouds as an area of green surrounding the aircraft. WARNING If High Altitude Ice Crystal conditions are suspected exit the region as soon as practicable.

4.4 Radar Interpretation, Navigable/Non-Navigable Weather  4.4.1 Intr odu cti on : Due to MultiScan’s use of Variable Temperature Based Gain it is normal to see green returns at cruise altitude that were not visible with previous generation radars. The radar can now see the low reflectivity returns between cells as well as the extreme tops of lower lying weather. In many cases these areas of green are navigable and represent light to moderate chop. However, proper radar interpretation must also take into account the appearance of thunderstorm cells. A normal thunderstorm is circular or oval in shape with shallow gradients. Variations from this normal shape are indicative of shear conditions within the thunderstorm and can serve as clues to hazardous weather.

Normal thunderstorms are circular or oval in shape with shallow gradients.

 A distorted cell shape (indicative of internal shear conditions) and steep gradients are associated with hazardous weather.

4.4.2 Navigable Weather 

Example 1: On the following page the view out the captain’s window shows a “ridge” of weather at 25 NM. This “ridge” is actually the extreme top of weather that is well below the aircraft. Because there is no major cell activity displayed in conjunction with the green returns this weather is navigable and the crew can anticipate light to moderate chop. With older generation radars this green area of weather would not have been visible and light to moderate chop would have occurred unexpectedly upon penetration.

43

Weather band at 25 NM

The extreme top of low lyi ng weather appears as a green band at 25 NM on the radar dis play.

The band of weather at 25 NM represents the extreme top of weather that is well below the aircraft. Since there is no major cell activity, the green returns on the radar display represent navigable weather and the crew can anticipate light to moderate chop.

Example 2: This 787 display (below left) shows normal thunderstorm activity. The circular shape of the cells and the shallow gradient between colors indicates convective activity but no unusual threats. In this case, green represents the outer boundaries of the cells and the pilot chose to navigate between the two cells containing yellow cores. Whenever possible, avoid all thunderstorm activity by 15-25 NM. However, when navigation between cells is required, these type cells present the lowest thunderstorm threat.

Route Navigated

 As the pictures out the First Of fice’s window show, the cells on the display represent relatively benign air mass thunderstorms. The circular/oval shapes and shallow gradients indicate convective activity but no unusual threats.

Example 3: In this picture a potential transit corridor has filled with green at approximately 40 NM due to STC limitations within the radar (see section 3.4.2, Sensitivity Time Control, for details). Decreasing attenuation has made it possible for the radar to see the low re flectivity returns between the cells that would normally not be displayed. Light to moderate chop would be expected in these circumstances.

Transit Corridor fills with green

44

4.4.3 Non-Navigable Weather 

Example 1: At initial glance the weather displayed at the top of the next page looks relatively benign. The gradient between colors is shallow and there is not a prominent red core. However, the two fingers that extend to the right of the cell’s core indicate an internal shear force. Even though these returns are green, they still represent a threat to the aircraft. In fact, the dark area between the two fingers is an indication of a potential hail shaft and should not be transited. Example 1: The area between the two “fingers” that extend to the top right of this cell is indicative a potential hail shaft.  Although the bottom finger paints green, it should not be transited.

Potential Hail Shaft

Example 2: The radar below is displaying two fingers that emanate from the main cell in the upper left of the display. Again, this is an indication of a possible hail shaft. In addition, the hook at the end of the bottom finger has sometimes been associated with the development of tornadoes.  Avoidance of these type cells by 15 - 25 NM is recommended. Example 2: The “hook” in the center of the display has sometimes been associated with developing tornadoes.

Potential Hail Shaft

Hook

Example 3: The irregular shape of the cells (top next page) indicate severe weather. Steep gradients between colors are associated with very strong updrafts and downdrafts. The finger at the bottom of the center cell indicates strong shear forces and the U-shapes in both cells indicate possible hail shafts. Avoid these types of cells by 15-25 NM whenever possible. 45

Example 3: The steep gradients of these cells indicate severe turbulence. The U-shapes associated with each cell are potential hail shafts.

Potential Hail Shafts

Steep Gradient

Example 4: Notice the very irregular/scalloped edges of the top right hand cell below. This is indicative of significant shear forces within the cell causing turbulence outside the cell boundaries. One could expect moderate to severe turbulence flying in black along the right-hand edge of the cell Example 4: Scalloped edges indicate signi ficant turbulence may extend outside the cell boundaries.

Scalloped Edges

4.4.4 Non-Refl ecti ve Weather : As mentioned is Section 3.1 not all weather meets the required threshold to be displayed. Stratiform clouds and small cumulous build ups (see below) often fall into this category. The popcorn shaped clouds pictured at 15,000 ft. are associated with light to moderate turbulence but are too dry to be displayed.

The up drafts (building cells) and down drafts (clear areas in between) associated with popcorn shaped cumulous build ups can result in light to moderate turbulence. However, these type clouds do not contain enough moisture to reflect radar energy.

46

4.5 Radar Interp retati on, Oceanic Weather : Oceanic cells are far less reflective than land based cells and the majority of the majority of the water content is located at lower altitudes (see section 5.1.4.1, Worldwide Weather Variation, for details). In order to estimate whether or not the cell top reaches the aircraft’s altitude, the radar measures the height of the re flectivity in the lower portion of the cell. Weather models are then used to estimate the cell’s actual height (see section 5.1.4.2, Geographic Weather Correlation Technology, for details). Because oceanic cells tend to rain out at low altitude they are notoriously dif ficult for the radar to display properly.

Example 1: In the example below notice that a small oceanic cell with a red core is visible at 120 NM. The cell continues to display a red core through the 100 NM, 40 NM and 20 NM range scales and stays on the display until it passes behind the aircraft. The cell is initially visible through the haze at 20 NM and fully visible at approximately 2.5 NM.

120 NM

100 NM

Nonre fl ective oceanic cell Oceanic cells are approximately 200 times less re flective than land base cells and the majority of the water in the cell is located at low altitudes.

40 NM

20 NM

In this example an oceanic cell that would normally be dif ficult to detect is displayed properly because the radar is looking for water content at low altitudes.

47

Example 2: In the following example a small cell is displayed on the ND near the aircraft flight path at 120 NM. It initially has a small red core which turns to yellow by 80 NM and then green by 50 NM. Since the cell does not reach the altitude anticipated by the radar it eventually falls below the radar beam and is removed from the display at approximately 35 NM.

 At 120 NM it is dif ficult to tell visually if these cells are at or below the aircraft flight path. But at 40 NM it is clear that they are below the aircraft and not a threat.

120 NM 80 NM

60 NM

40 NM

Because the cell is below the aircraft it decreases in intensity and size as the aircraft approaches it and then disappears from the display at approximately 35 NM.

Recommendations: (1) If cell characteristics do not change between 120 and 60 NM (i.e. the size and color remain the same), then the cell is more than likely at the aircraft altitude and a deviation should be requested. (2) If a cell that is visible at 120 NM begins to decrease in intensity by 60 NM then an immediate deviation decision is not required. More than likely it will continue to decrease in intensity and eventually fall off the display. The flight crew should monitor the cell and watch to see how it changes over time. If the cell deteriorates to green and falls off the display (normally around 35 NM), then it is beneath the aircraft altitude and no deviation is required. (3) A small green cell that remains on the display is an indication that the aircraft will clip the top of a lower lying convective cell and moderate turbulence is possible. 48

5.0 How the (MultiScan ThreatTrack) Radar Works 5.1 Primary Techno log ies : MultiScan ThreatTrack analyses weather in different phases of flight to provide a threat picture (as opposed to a traditional radar that simply shows the amount of moisture in the atmosphere). MultiScan ThreatTrack uses five key technologies that work behind the scenes to enable thunderstorm detection and analysis including (1) Flight Path Hazard Analysis, (2) Beam to Beam Power Comparison, (3) Automatic Temperature Based Gain, (4) Geographic Weather Correlation, and (5) Track While Scan Cell Analysis 5.1.1 Flight Path Hazard Analysis : Mature thunderstorms produce hail, lightning and turbulence threats outside the cell boundaries at all altitudes. And turbulence can be experienced anywhere. But Take Off/ Landing, Climb/Descent and Cruise each have their own unique threats. During Take Off and Landing windshear is a prime consideration. During Climb and Descent pilots are concerned about weather along the aircraft flight path and lighting potential in the vicinity of the freezing level. At Cruise the primary threat is inadvertent thunderstorm top penetration and turbulence from rapidly growing cells.

Flight Path Hazard Analysis adjusts the radar’s detection and analysis parameters based on phase of flight to provide a more accurate threat picture for flight crews. See the chart below for functions that are activated in various stages of the flight. In Route: (1) Geographic Wx Correlation (pg. 55) (2) Automatic Temp Based Gain (pg. 55) (3) OverFlight Protection (pg. 62) (4) Predictive OverFlight (pg. 30)

Take Off/Landing (1) Forward Looking Windshear (pg 40)

NOTE

Climb/Descent: (1) Flight Path Wx Scan (2) Mid Altitude Associated Threat (pg 32)

 All Flight Phases: (1) Core Threat Analysis (pg 30) (2) Mature Cell Associated Threat (pg 33) (3) Two Level Enhanced Turbulence (pg 31) (4) PAC Alert (pg 38)

MultiScan ThreatTrack automatically looks for weather below the aircraft when a descent rate of 250 ft/min minute or greater is detected. Therefore, it is no longer necessary to momentarily go to manual at top of descent to scan for low lying weather as in previous versions of the software (see section 7.4.2). 49

5.1.2 Beam t o B eam Power Compari son 5.1.2.1 The Challenge: When a radar beam paints a target the return comes back to the aircraft as a single pulse indicating something (or some group of things) is at a particular range. The return does not contain discreet digitized data that can be separated into different components like terrain and weather.

Radar paints target(s) Return is a sing le pulse containing range inform ation on the target(s)  A radar ret ur n of tar get s at a par ti cu lar ran ge i s c om po sed of a si ng le pu ls e. It is not digiti zed data that can be easily separated in to t he different compo nent targets.

In addition, remember from section 3.5 that the width of the radar beam makes it very dif ficult to accurately determine heights of targets at extended ranges. And finally, a radar beam is similar to the flashlight beam shown below left. The flashlight beam has an inner core or “hot spot” (equivalent to the 3.5 o radar beam). The beam also has a corona and (side) spill area where objects with distinct edges or that are very reflective would be visible. In the same way, radar beam side lobes may detect objects outside of the normal 3.5 o beam width (at 6 o or even 9o). With certain types of terrain such as the cliff face displayed below, very strong returns will show up further out on the edge of the beam and unexpectedly introduce ground clutter into the picture. Cities are even a greater problem because man made structures are very strong radar reflectors, and again, introduce clutter into the side lobes of the radar beam. Therefore, a simple ground clutter removal strategy that only uses tilt will invariably introduce unwanted clutter into the picture. Flashlight Beam S     i de  p i    l   l     S o  r n    o a      C

Hot Spot

Objects may be detected outside the center of a flashlight beam. Similarly, radar side lobes may also pick up returns outside the normal 3.5o beam width

Certain types of terrain such as cliff faces and man made structures such as cities are very strong radar reflectors. Radar side lobes may pick up returns from these type objects well outside the normal 3.5 o beam width, complicating the removal of ground clutter from the display.

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5.1.2.2 Grou nd Clutter Elimination : MultiScan’s Beam to Beam Power Comparison is the enabling technology that facilitates Ground Clutter Elimination and the Quiet, Dark Cockpit Philosophy. MultiScan eliminates ground clutter by using an internal terrain table to draw a line that is conformal to the earth’s surface. The radar then uses two radar sweeps at two different tilt angles to examine the area in front of the aircraft. The different tilt angles result in different strengths in the returns of the same target. By doing a power to power comparison it is possible to determine if a return falls below or above the conformal line. Returns that fall below the line are eliminated as ground clutter. Returns that are above the line are considered to be weather. Beam to Beam Power Comparison is also able to remove clutter outside the normal 3.5 o beam width (see previous section). Ground clutter removal

Beam to Beam Power Comparison

C o 

n f o  r  m 

al  Line

Targets below the conformal line are eliminated as ground clutter 

The two pictures below demonstrate the effectiveness of the Beam to Beam Power Comparison technology in eliminating ground clutter. The first photo is the best interpretation that was achievable in MAN mode using a variety of TILT and GAIN settings. Weather returns are masked by ground returns. The second photo is in AUTO/CAL mode and shows weather at 230 NM. The second picture clearly showed only significant weather approaching Hong Kong (4 hours before forecast). The radar’s early warning provided almost 10 minutes additional warning, which was significant because the cells threatened both HKG and the primary alternates.

MAN Operation Wx returns masked by ground clutter

AUTO/CAL Operation Wx returns clearly visible at 230 NM

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5.1.2.3 Quiet, Dark Cockpit : Beam to Beam Power Comparison algorithms correct for the curvature of the earth, beam diameter, and for atmospheric anomalies that affect the shape of the beam in order to determine the precise location of the return. A tenth order polynomial with coef ficient inputs that, in part, include altitude, geographic location, land/ocean environment, and time of year is then used to develop Geographic Weather Thresholds in real time. If the beam to beam power comparison yields a return that exceeds the threshold, weather is displayed. A return below the threshold is classi fied as non-threat and not displayed in line with the Quiet, Dark Cockpit philosophy. Quiet, Dark Cockpit

6,000 ft. beneath the aircraft altitude (approximate)

Beam to Beam Power Comparison

Weather targets below the 6,000 ft. line (approximately) are not displayed

NOTE Cell top measurement begins at 120 NM with the intent of having accurate deviation information by 80 NM. The end result is a Quiet, Dark Cockpit. Only threats at the aircraft altitude are displayed making navigation decisions easier and more ef ficient and reducing crew work load.

Cells at 160 NM

Cells at 70 NM Shear 

Cells at 70 NM

Non-threat Wx is not displayed

Non-threat Wx

Shear 

Quiet, Dark Cockpit: Note that only threat weather is displayed. In addition, the prominent cell at the 11:00 O’clock position has an internal shear force that can be seen out the windscreen as a secondary cell. Also notice the cells at 70 NM and the cells coming on to the display at 160 NM.

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5.1.3 Automatic Temperatu re Based Gain : A fundamental problem that can lead to inadvertent thunderstorm top penetration is the fact that the tops of thunderstorms are nonre flective. Thunderstorm tops are composed primarily of ice crystals which are very poor radar re flectors. Thus, every thunderstorm has a radar top (re flective top) and a visual top (what you can see with your eyes) and they are very seldom the same. Visual Top  A primary threat to en route weather avoidance is the fact that thunderstorm cell tops are nonre flective Radar Top

 As discussed in section 3.1.2, when AUTO is selected the radar automatically increases gain as outside air temperatures decreases in order to put more energy on the nonre flective thunderstorm tops. Thus, by the time the aircraft reaches cruise altitude AUTO CAL Gain and MAN MAX Gain are roughly equivalent . This essentially moves the nonreflective portion of the storm (the radar top) higher in the cell, makes more of the cell visible to the radar and helps prevent inadvertent cell top penetration.

Radar Top with  Automatic Temperature Based Gain

Radar Top without  Automatic Temperature Based Gain

 Automatic Temperature Based Gain moves the nonreflective portion of the storm (the radar top) higher in the cell to reduce the likelihood of inadvertent thunderstorm top penetration.

5.1.4 Geographic Weather Correlation TM 5.1.4.1 World wide Weather Variati on : Due to the signi ficant variation of worldwide thunderstorm characteristics a signi ficant challenge for an automatic radar is providing a consistent worldwide threat picture. Scientists have long known that thunderstorms display very different characteristics depending on where they are in the world and whether

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they develop over land or over water. For instance, a typical central  African cell has very strong updrafts that carry water content to high altitudes. These cells also exhibit significant convective activity well above the freezing level. In contrast, a Central Paci fic cell may look very similar on the outside, but its internal characteristics are normally vastly different. Updrafts are not as severe, high altitude moisture content is far less, and there is less convective activity in the cell.

(Kelvin)

Central African cells are normally characterized by severe updrafts of 20-40 m/s and a strong (red) reflective core that reaches to 23,000 ft.

(Kelvin)

The exterior of a typical Central Paci fic cell may look similar to a Central African cell, but it is typically characterized by more moderate updrafts of 5-15 m/s and the strong (red) reflective core reaches to about 16,750 ft.

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In the chart below note that all cells demonstrate strong re flectivity characteristics below the freezing level. However, at cruise altitudes Mid-Latitude Continental cells are, in general, 20 dB (200x) more reflective than Equatorial Oceanic cells. Equatorial Continental cell reflectivity characteristics fall in between. Thunderstorm Vertical Refl ectivity Characteristics (Based on Region) Land masses cause differential heating that produces strong updrafts. Thus moisture is carried to high altitudes and increases the reflectivity of land based cells. Oceanic regions, however, act as a heat sink (constant temperature) resulting in only moderate updrafts and less moisture/reflectivity at higher altitudes.

20 dB Difference in Refl ectivity

Cruise 35,000’    )    t   e   e    F    (    t    h   g    i   e    H

   l    l    l   e   a    i   r    C   c   o    i    t   a   n   u   a   q   e    E   c    O

Freezing Level 16,000’

Mid-Latitude Continental Equatorial Continental Equatorial Oceanic

   d   n   a    L    l   a    t   n   e   n    i    t   n   o    C

   l    l   e    C    d   e   s   a    B

Maximum Reflectivity (dBz)

Equivalent Aircraft Display Colors (Calibrated Radar Display)

Bay of Bengal

Equatorial Oceanic cells rain out at low altitudes and tend to be non-reflective even though the cell tops extend to the aircraft altitude.

Brazil

Equatorial Continental cells fall in between the high reflectivity of Mid-Latitude Continental cells and the low reflectivity of Equatorial Oceanic cells.

United States

MidLatitude Continental cells have high moisture content at cruise altitudes and are more reflective making inadvertent cell top penetration less likely.

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 A further complication to an automatic radar providing a consistent worldwide threat picture is the fact that thunderstorm threats change significantly as the intertropical Convergence Zone (ITCZ) shifts location with the changing seasons. December

Net Radiation

March

Net Radiation

June

Net Radiation

Seasonal variations in the Intertropical Convergence Zone (ITCZ) result in differing thunderstorm reflectivity characteristics over the course of the year.

5.1.4.2 Geographic Weather Correlation Technology : The launch of the TRMM (Tropical Rain Forest Measuring Mission) satellite in 1997 greatly contributed to the understanding of worldwide convective activity. TRMM has recorded tens of millions of data points since first placed in orbit and there is now a robust set of data that allows scientist to accurately model worldwide thunderstorm characteristics. In 2004 Rockwell Collins teamed with Dr. Ed Zipser, one of the world’s leading climatologists, to use the TRMM data to developed worldwide thunderstorm models that were introduced into the radar in 2009. For every 10 by 10 degrees of latitude and longitude the radar adjusts thresholds based on geographic position, time of year and whether or not the aircraft is in an oceanic or land based environment. For low reflectivity cells thresholds are set to lower altitudes. Conversely, in regions with high re flectivity characteristics thresholds are set higher. This provides a robust prediction of whether or not the storm top extends to the aircraft altitude. The end results are a reduction in the possibility of inadvertent thunderstorm top penetrations in low re flectivity regions and a minimization of unnecessary deviations in high re flectivity areas. TRMM Profiles CloudSat Profiles Climatology Models

MultiScan contains a robust worldwide threshold database developed from the millions of data points collected by the TRMM satellite. Thresholds are adjusted based on geographic position, time of year and flight environment (land/ocean) for every 10 by 10 degrees of latitude and longitude.

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Threshold Threshold

Threshold

Oceanic

Equatorial Continental

Mid Latitude Continental

In low reflectivity areas such as oceanic environments cells tend to rain out at low altitudes but the cell top still reaches to the aircraft flight path. In these areas thresholds are set low (i.e. perhaps 22,000 ft.) in order to ensure cell tops are properly displayed and inadvertent cell top penetration is prevented. Continental land based cells are highly reflective so higher thresholds (i.e. perhaps 28,000 ft. ) ensure proper display of the cell top and minimize unnecessary deviations.

Geographic Weather Correlation utilizes storm models to predict the actual (non-re flective) cell top to prevent inadvertent cell top penetration in low re flectivity regions and minimize unnecessary deviations in high re flectivity areas. 5.1.4.3 Low Lying Stratifor m Weather Anomali es: There will be occasions where the storm models do not match the actual weather and the system over warns. This may occur during oceanic flight when stratiform weather is beneath the aircraft. Due to the non-re flective nature of oceanic thunderstorms the thresholds (described above) are set at fairly low altitudes to ensure that convective thunderstorm tops are properly displayed. However, when low lying stratiform conditions are encountered instead of convective cells, the low lying weather may be displayed. These returns are normally green and should not require deviation (see Radar Interpretation, Section 4.0). In addition, the returns will normally fall off the display at approximately 30-40 NM.

Stratiform weather is visible several thousand feet beneath the aircraft

 A mismatch of the storm models has resulted in (primarily) green returns on the ND

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5.1.5 Track While Scan Threat Analys is 5.1.5.1 Why Threat Analysis? : Thunderstorm threat analysis is necessary because it is dif ficult to accurately determine the hazardous nature of a cell by simple observation of either the cell exterior (see Section 5.1.4.1) or the color of the radar returns. The magnitude of the threat depends on where the convective activity is located in the cell, the temperature where the convection is occurring, the stage of cell development and many other factors. Furthermore, standard reflectivity levels for red, yellow and green returns were first developed for mid altitude cells in the mid 1960’s and do not directly correlate to the nonreflective nature of cell tops at today’s cruise altitudes*. Thunderstorms may look the same externally or on the radar display but actually present widely different threat levels. Real time analysis is required to determine the actual threat

*Synopsis of a Thunderstorm Research Program (Rough Rider) for 1966-67. Technical Report ASD-TR-68-29, 1968

5.1.5.2 Track While Scan Techn ology: MultiScan Threat Track uses a Track While Scan technology that tracks up to 48 thunderstorm cells while scanning the area in front of the aircraft for additional threats. Convective weather discrimination then identifies convective cores and areas of stratiform rain. At altitude, non-threat stratiform weather is de-emphasized (yellow turned to green) so that convective cores will be clearly visible to the flight crew. Track While Scan Technology enables the radar to track up to 48 thunderstorms while scanning for additional threats

This picture compares the ground based radar image (left) with the cores being tracked by the radar (right). The radar assigns each core a number and then maps the size of the convective contours.

Threats are prioritized and individual vertical analyses performed for a real time analysis of cell threats

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5.1.5.3 Individu al Cell Analy sis : Once the cell cores are identi fied, individual high resolution thunderstorm assessments are performed. High resolution vertical scans are the equivalent of up to 120 horizontal scans yielding precise information concerning the thunderstorm makeup.

Thunderstorm assessment includes the mapping of the internal cell reflectivity structure over the entire vertical extent of the cell and the identi fication of the peak reflectivity. A high resolution Vertically Integrated Liquid (VIL) assessment determines the amount of water at various altitudes within the cell. Significant convective energy is required to lift large amounts of liquid to high altitudes and a VIL is a good indication of thunderstorm intensity. The Key elements used in radar also correlates outside air temperatures with individual cell analysis include the intensity and the reflectivity levels of returns to determine hail altitude of convective and lightning probabilities. In addition, storm top activity, the temperature and growth rate analysis are performed. Because where the convective activity is occurring, uphail is often thrown out the top of the cell and in the downwind direction, upper level wind direction per level wind information and cell growth rate. and velocity are used to predict the downwind hail threat region (see Section 3.3.2.3). And finally, the radar creates a buffer area above cells that are beneath the aircraft that directly correlates to the growth rate (i.e faster growth rate, larger buffer area). If the buffer area intersects the aircraft altitude then the Predictive OverFlight icon is displayed (see Section 3.3.1.2). In all, over 100 cell attributes are measured and analyzed. 5.1.5.4 Cell Life Cycle: The stage of life cycle development of a cell is also a key indicator of a thunderstorm’s threat. A typical air mass thunderstorm has about a 60 minute life cycle (Multi-cell storms last approximately three hours). Cumulous

0 Minutes 8

15 Cloud to cloud lightning

Mature

23

30

38

Dissipating

45

53

60

More severe cloud to ground lightning

Lightning potential exists during the latter cumulous stage and the mature stage of thunderstorm development. During the Mature stage additional threats include hail and severe turbulence which may extend outside the cell boundaries

59

During the early developing cumulous stage and late dissipating stages of the cell threats are relatively minor. However, during the later stages of cumulous development, cells do become electri fied around the freezing level due to the collisions between positively and negatively charged ice particles. This resulting electrical potential forms the basis for possible lightning discharges. During the mature stage of a thunderstorm hail and turbulence may extend outside the cell boundaries and severe cloud to cloud and cloud to ground lightning is possible. MultiScan ThreatTrack uses the cell life cycle information to differentiate between the various cell threats. For instance, late stage cumulous cells are primarily a lightning threat in the vicinity of the freezing level (see section 2.4.3.2.1) while mature cells pose turbulence, hail and lightning threats at all altitudes (see section 2.4.3.2.2). 5.2 Secon dary Technolog ies 5.2.1 OverFlig ht Protection : Traditional manual operating techniques point the radar into the lower re flective part of the thunderstorm for best weather detection. However, as the aircraft approaches the cell, the beam moves higher into the nonre flective portion of the cell and it tends to disappear from the display. OverFlight Protection looks 6,000 ft. beneath the aircraft to keep the re flective portion of the cell in view, and, as the cell nears the aircraft, uses computer memory to prevent its falling off the display. Once again, Over flight Protection reduces the chances of inadvertent thunderstorm top penetration.

Direction of Flight

When a cell top is at the aircraft altitude it is common for the storm to fall off the display as the aircraft nears it due to the fact that the radar beam is no longer scanning the re flective portion of the cell.

 As seen on this 747 display, with OverFlight protection this low reflectivity oceanic cell stays on the display until it passes behind the aircraft. The pilot commented that it is not unusual for this type of cell to fall off the display 40 NM from the aircraft and then give the aircraft a good “thump” should the crew fly into it.

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5.2.2 SmartScan : SmartScan ensures real time weather updates during aircraft turns. When an aircraft turns a black wedge appears on the display due to the fact that the radar antenna has not yet scanned this new weather region. This condition is made worse with new automatic radars that take multiple sweeps to fill the memory buffer before the weather information is displayed. When an aircraft turns, SmartScan begins a sector scan in the direction of the turn and weather that is falling off the back side of the display is “pasted in” from the memory buffer. The result is that MultiScan actually updates the display with real time weather more rapidly in AUTO (even with multiple scans) than the radar can in manual with only one scan.

SmartScan enables real time weather updates in the direction of aircraft turn Wx from memory buffer completes Wx picture SmartScan sector scan in direction of turn SmartScan uses a sector scan in the direction of the aircraft turn to ensure that the Wx picture is rapidly updated even when multiple scans are being used to gather Wx data. Wx that is falling off the display is “pasted” from the computer’s memory buffer to provide a total Wx picture.

No “wedge” even during 45o turn

Notice the absence of a black wedge during this 45 o turn. SmartScan enables real time weather information right at the edge of the display and provides the maximum amount of time for avoidance decision making.

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5.2.3 TrueZero Three Axi s Trim Correcti on : An aircraft may produce tilt errors that are invisible to the radar. For instance, a 0.7 degree tilt error has been consistently observed on one air transport aircraft, and this i s equivalent to a miss in altitude of approximately 7,000 ft. at 220 NM. An error of this magnitude could either introduce ground clutter into the picture of over scan long range weather. MultiScan’s TrueZero algorithms compare the radar returns with the radar’s terrain table information, and a three axis trim correction is made and stored in the computer’s memory for use on the current and future flights. The algorithms are activated when the aircraft is level and above 17,000 feet AGL with terrain occupying the majority of the field of view. In optimal conditions capture can occur in as little as 5 minutes. This is a continuous process that further refines the tilt over time.

NOTE If a new R/T has been installed in the aircraft ground returns may be displayed on the aircraft’s initial climb out. Once the aircraft is level above 17,000 ft. AGL and the three axis trim correction is applied, ground returns should disappear from the display. 5.2.4 Radar Scan and Tilt Philos oph y : When AUTO is selected MultiScan uses two radar sweeps at two different tilt angles to collect terrain and weather information. The separation between the beams remains constant. The displayed tilt angle is the average of these two beams. The resulting returns are digitized and stored in a temporary memory buffer. At take off tilt will be approximately +5 degrees, although it may be higher if surrounding terrain has signi ficant height. At 10,000 ft. AGL the tilt angle is approximately zero. And above 10,000 ft. AGL the bottom scan is always centered on the radar horizon. Thus, tilt indications will gradually decrease as the aircraft climbs above 10,000 ft AGL.

During each horizontal sweep vertical sweeps are scheduled as required and are transparent to the flight crew. The Predictive Over flight function (see Section 3.3.1.2) uses a low tilt horizontal sweep to look for cells below the aircraft. If candidate cells are identi fied additional vertical sweeps are performed to assess the growth rate. NOTE The Track While Scan technology allows the radar to utilize radar scan time ef ficiently on the highest priority weather targets rather than using multiple horizontal sweeps that mostly scan empty space.

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6.0 Manual Operating Techniques WARNING When MAN is selected the radar functions as a traditional weather radar. Tilt and gain must be controlled manually.  AUTO is recommended in all phases of flight.

WARNING In MAN mode automatic features that are designed to prevent inadvertent thunderstorm top penetration (Temperature Based Gain, OverFlight Protection, Geographic Thresholds) are disabled. See section 6.1.3.3 for special manual procedures to prevent inadvertent cell top penetration.

6.1 Tilt Contr ol

IMPORTANT Tilt Control is the most important factor for proper manual operation of the radar. NOTE In most instances, the flight crew is looking for a compromise tilt angle between too much ground returns and too little weath er returns. The best tilt setting will vary depending on the aircraft phase of flight (i.e. low altitude, mid altitude and high altitude).

Low Reflectivity Too High

High Reflectivity

Compromise

Too Low

During manual operation the best tilt angle i s most often a compromise between a tilt angle that causes too much ground clutter and a tilt angle that detects too little weather.

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6.1.1 Low Altitu de Tilt Contro l (Below 10,000 ft.): Below 10,000 ft. a tilt setting of +5o is recommended. Below 10,000 ft. the flight crew is busy with a variety of tasks from check lists to talking with approach/departure control. Setting a +5o tilt and leaving it set through 10,000 ft. reduces cockpit work load. The +5o setting will eliminate most ground clutter and detect the majority of the weather in the immediate vicinity of the aircraft. 6.1.1.1 Initial Clim b Out : It is typical for a two engine air transport category aircraft to climb out after take off at approximately 240 kts with a 3000 fpm rate of climb. This equates to a 7 o climb angle. Since the radar beam is approximately 3.5o wide, a +5 o radar tilt angle keeps the outer edge of the radar beam pointed close to the aircraft flight path, provides adequate weather detection ranges, and eliminates most ground clutter.

Climb out flight path (+7 degrees)

Radar Tilt (+5 degrees)

o

Below 10,000 ft. a tilt angle of +5  is recommended.

WARNING  Above 10,000 ft. tilt should be adjusted downwards (see section 6.1.2.1). Failure to adjust the tilt downward above 10,000 ft. may cause the radar to over scan the re flective portion of cells and result in inadvertent thunderstorm top penetration.

6.1.1.2 Descent below 10,000 ft. : Below 10,000 ft. a +5 o tilt angle remains the preferred tilt. Since weather is generally highly reflective below 10,000 ft., a +5 o tilt angle will detect most weather while at the same time eliminating the majority of ground clutter. The benefit to a +5o tilt angle is that this tilt setting can be set and forgotten during the critical approach and landing phase of flight, thus reducing crew work load.

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6.1.2 Mid Altitude Tilt Cont rol (10,000 - 25,000 ft.) 6.1.2.1 Tilt Technique, 40 and 80 NM Ranges Scales : The best general guideline for the 40 and 80 NM range scales is to tilt the an tenna until ground returns appear at the outer edge of the display. This tilt setting will keep the beam looking down into the re flective part of the thunderstorm, prevent over scanning and reduce the possibility of inadvertent thunderstorm top penetration.

Tilt Techn ique: 40 and 80 NM Range Scales

Clutter ring at edge of range scale

The radar tilt has been set to display clutter at the outer edge of the 80 NM range. This will keep the beam pointed into the re flective part of thunderstorm cells and reduce the possibility or inadvertent thunderstorm top penetration. In most cases the clutter ring will be solid, but in this particular instance the terr ain is mountainous and the returns are patchy. Note that this tilt technique also works to set the proper tilt for the 40 NM range scale.

NOTE 80 NM is the best tactical range scale for weather detection and avoidance and should be used to determine deviations. 65

6.1.2.2 Tilt Technique, 160 NM Ranges Scale : Setting the proper tilt for the 160 NM range scale is more dif ficult. Due to the curvature of the earth the edge of the beam is parallel to the earth’s surface at this range and it is not possible to get a solid clutter ring at the edge of the display. In this case, lower the tilt until ground clutter is displayed. Then slowly raise the tilt until the display is covered with what appears to be electronic “noise”. This ensures that the edge of the beam is right at the earth’s surface. Solid returns are cells that are poking up through the clutter.

Til t Techn ique: 160 NM Range Scale

Thunderstorm Cells

"Noise"

"Noise"

"Noise"

Electronic "noise" or speckles indicate that the edge of the beam is right at the earth's surface and that tilt has been set properly for the 160 NM range scale. Thunderstorms are visible through the clutter.

WARNING The 160 NM range scale should be used strategically for detection of long range weather. Tilt will be higher than for the 80 NM range scale and this increases the likelihood of inadvertent cell top penetration. After viewing the long range weather, return to the 80 NM range scale. 66

6.1.3 High Alti tud e Tilt Guidelin es (25,000 ft. and A bov e) 6.1.3.1 High Alt itu de Tilt Control : At higher altitudes the exact same tilt techniques are used as at mid altitudes: ground clutter in the outer edge of the 40 and 80 NM range scales and clutter specs or “noise” for the 160 NM range scale. The major difference is that at higher altitudes thunderstorm tops may become completely glaciated (formed entirely of ice crystals) and reflect very little radar energy. This significantly increases the risk of inadvertent thunderstorm top penetration and special precautions should be used to keep the aircraft safe.

WARNING Over-scanning and subsequent inadvertent thunderstorm top penetration is a signi ficant threat during high altitude manual operations. 6.1.3.2 Over Scanni ng : It is not unusual for cells to fall off the display as they approach the aircraft even though tops are still at the aircraft altitude. This occurs because at a constant tilt setting the radar progressively scans higher in the cell as the aircraft approaches it.

Direction of Flight

Tilt set properly. Clutter ring at edge of range scale

Cell at 60 NM

Cell at 40 NM

Cell at Cell at 30 NM 5 NM  As the aircraft approaches a thunderstorm the beam will progressively scan higher into the non-reflective portion of the cell (top picture). Thus, the cell may fall off the display even though the top is still at the aircraft altitude. The circled cell (bottom pictures) is 2,000 ft. above the aircraft altitude, but falls off the display at 25 NM due to over scanning.

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6.1.3.3 Over Scannin g Preventi on Metho ds 6.1.3.3.1 Method 1 - 80 NM Tactic al Rang e Scale : Use the 80 NM range scale as the primary weather avoidance range scale. Set tilt so that ground clutter displays along the outer range scale and track approaching cells through the clutter ring. If the cell stays on the display until 40 NM its glaciated (non-reflective) top may be at the aircraft altitude. Avoid the area where the cell is located even though it no longer appears on the display. 80 NM Tactical Weather Display - If the cell stays on the display until approximately 40 NM the non-reflective top may be at the aircraft altitude and the position where the cell is located should be avoided.

Weather moving through clutter ring

WARNING Cells that fall off the display within 40 NM of the aircraft should be avoided, even though they are no longer on the display. The non-reflective cell top may still be at the aircraft altitude. 6.1.3.3.2 Method 2 - 40 NM Over Fligh t Protecti on : The threat of overscanning can be reduced by periodically selecting the 40 NM range scale and adjusting the tilt so that some clutter appears in the outer most range scale. This significantly reduces the tilt and looks much lower into the reflective part of the storm. If cells that are at the aircraft altitude disappear within 40 NM of the aircraft, selecting the 40 NM range and applying this tilt technique should keep them in view until they pass behind the aircraft. The 40 NM range scale tilt setting is relatively low and will sometimes pick up weather that is beneath the aircraft and does not need to be avoided. However, it does have the signi ficant benefit of preventing inadvertent thunderstorm top penetration. Since the Boeing control panel is a Split Function Control Panel (see Section 2.1), a good technique is

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for the Pilot Flying (PF) to set tilt for 80 NM and Pilot Not Flying (PNF) to set tilt to 40 NM. Thus the PF can make deviation decisions using the 80 NM (primary tactical) range scale and the PNF can monitor potential Over Flight conditions on the 40 NM range scale.

80 NM Range Scale

40 NM Range Scale

 Aircraft at 35,000 ft. Captain’s tilt set for the  Aircraft at 35,000 ft. First Of ficer’s tilt set for 80 NM range scale. 40 NM range scale. Note the “finger” (see Section 4.3.2.3) directly in the aircraft path that has disappeared from the 80 NM range scale display

NOTE For best tactical situation awareness pilots can select different range and tilt settings. When different tilts or modes are selected, the radar will update the Captain’s display on every right to left radar scan and the First Of ficer’s display on every left to right scan. Thus, display updates will occur every eight seconds and will alternate between the Captain and First Of ficer’s NDs. 6.1.3.3.3 Metho d 3 - MAN MAX Gain : Increasing gain at cruise altitude increases the sensitivity of the receiver and allows the radar to do a better job of displaying the non-re flective thunderstorm tops. This is especially true over the ocean where the tops of very low re flectivity cells are extremely dif ficult to detect. MAN MAX gain is advisable during cruise and is highly recommended for oceanic flight (see Section 3.1.1 “GAIN - Manual Operation” for information on manual use of gain, and Section 4.0 for radar display interpretation when increased gain is applied). MAN CAL gain tends to show only thunderstorm cores at cruise altitudes. This is especially true during oceanic flight.

MAN MAX gain gives the best possible cell representation during MAN operation.

MAN CAL gain

MAN MAX gain

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6.1.4 Tilt Setti ngs When Descending from High Alt itu de: If the tilt is set properly at cruise altitude and then is not raised as the aircraft descends the radar beam will progressively “dig” deeper into the ground. The result is a very colorful display of ground clutter that may fully mask weather returns. During descent tilt should be gradually raised to keep ground clutter in the outer range scale. Should the flight crew fail to do so ground clutter will progressively fill the display.

If the radar tilt is set to display clutter at the outer edge of the 80 nm range scale at a cruise altitude of 35,000 ft. and the aircraft then descends to 5,000 ft. without the tilt being adjusted, the picture to the right is the result. Ground clutter completely masks all weather returns.

6.1.5 Oceanic Tilt Setti ng s : When operating over water there may not be adequate re flectivity to display clutter at the edge of the range scale. Should clutter be insuf ficient for determining the appropriate tilt angle, the table below provides suggested tilt angles. The tilt settings place the radar beam at the edge of the outer range scale.  Altitu de

40 NM

80 NM

160 NM

40,000 ft.

-7o

-3o

-2o

35,000 ft.

-6o

-2o

-1o

30,000 ft.

-4o

-1o

0o

25,000 ft.

-3o

-1o

0o

20,000 ft.

-2o

0o

+1o

NOTE Tilt settings may not be exact. The radar changes tilt in 0.25 o increments, but only whole numbers were used. 70

6.2 Long Range Weather Detecti on : The ability to gather strategic weather information out to 320 NM during manual operation is possible if one understands the concept of the radar horizon and then adjusts tilt appropriately. Over a distance of 320 NM the curvature of the earth causes the earth’s surface to fall away by approximately 65,000 ft. Thus, if the aircraft is at 35,000 ft. at its current position, the earth’s surface is actually 100,000 ft. below the aircraft at 320 NM distance. The point where the earth’s surface falls below the radar beam and ground clutter is no longer displayed is the radar horizon.

When the radar beam is adjusted to eliminate ground returns it will scan over the top of weather that is over the horizon.

To detect over the horizon weather the radar beam should be adjusted so that it “peeks” over the radar horizon. To accomplish this first adjust the tilt for the 160 NM ranges scale (see Section 6.1.2.2). This puts the bottom edge of the beam right at the surface of the earth. Remember that the radar beam is 3.5 o wide (Section 3.5). Lower the tilt an additional 1.5o. This places the bottom half of the beam in the ground clutter and allows the top half of the beam to “peek” over the radar horizon.

Radar Horizon

The radar horizon is the point where earth’s surface has dropped below the radar beam and ground returns are no longer displayed. When the radar beam is centered on the horizon the radar i s able to “peek” over the horizon to detect long range weather.

The following picture shows the end result. The aircraft is at 23,000 ft. A down tilt of -2.5o has been selected by the pilot. The radar horizon is at 71

186 NM. Intermediate weather is masked by the ground, but long range strategic weather is now clearly visible at 300 NM. 300 NM Weather 

Radar Horizon

o

 Aircraft at 23,000 ft. Down tilt of -2.5 selected. Long range weather is visible over the radar horizon at 300 NM.

6.3 Recom mended Manual Radar Operatin g Procedures: It is recommended that pilots use the 80 NM scale as the primary tactical range scale for weather avoidance and deviation decision making. Periodic examination of the 160 NM and 40 NM range scales provides strategic weather information and over flight protection respectively. In addition, increasing gain at cruise altitude increases receiver sensitivity to best respond to the nonre flective nature of thunderstorms at the aircraft’s altitude. MAN MAX Gain at cruise altitude is recommended.

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7.0 Not Notes es 7.1 Manual Notes 7.1 No tes : This guide describes the operation of the Rockwell Collins WXR–2100 Series MultiScan ThreatTrack Weather Radar. To learn about speci fic operations of the radar refer to Section 2.0, “Controls”. For radar interpretation interpretation and pilot techniques refer to Section 3.0, “Displays” and Section 4.0 “Radar Interpretat Interpretation”. ion”. To learn more about the radar itself, refer to Section 5.0, “How the Radar Works”.

The general operating information in this guide must be supplemented with information contained in the Aircraft Flight Manual Manual (AFM). For general aviation weather, refer to the Federal Aviation Administration (FAA) AC 00–6A Aviation Weather for Pilots and Flight Operations Personnel. In some cases, there there is more than than one way to accomplish a task related to operation of the MultiScan Radar. In general, this guide describes only one method for accomplishing a speci fic task. NOTE The terms weather “threat” and weather “hazard” are used interchangeably in this manual. NOTE Illustrations in this operator’s guide are for illustrative purposes only. Some of the information shown is determined by other equipment installed in the aircraft, the Flight Management System (FMS) options installed, the interconnect wiring on the aircraft, and the regime of flight. NOTE Some aircraft operators can have special procedures that are different from those given in this operator’s guide. Refer to the applicable AFM for instructions speci fic for your aircraft or to the airline instructions for your speci fic operator. NOTE Most aircraft/airline operators establish guidelines for storm cell avoidance distances. distances. The crew has the sole responsibility responsibility to decide how close to approach various types of storm cells. It is suggested that these areas be avoided by no less than the minimum distance established by the flight operations department.

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The following Rockwell Collins trademarks are found throughout this operator’s guide. • MultiScan™ • MultiSc MultiScan an ThreatTrack™ • OverFlight™ • Predictive OverFlight™ • SmartScan™ • TrueZero™ • Geographic Weather Correlation™ • Track While Scan™ 7.2 Radiation 7.2 Radiati on Haz Hazard ard : The MultiScan radar uses 150 watts of energy. To provide a practical safety factor, the American National Standards Institute has speci fied a maximum level of 10 mw/cm 2 for personnel exposure of 6 minutes or longer to radar antenna electromagnetic electromagnetic radiation. The exposure time is limited to the amount of time within the antenna pattern pattern during each sweep. The Rockwell Collins Collins WXR-2100 radar system falls well below the 10 mw/cm2 standard. However, there is some disagreement that the 10 mw/cm 2 standard is low enough. Microwave ovens represent a more public safety concern and their leakage standard has been set at 4 mw/cm 2. The WXR-2100 power density is half or less than that of the microwave oven standard.

NOTE Some sources suggest that any radiation exposure can be harmful, especially long term. Each airline must make their own decision on this, as exposure to radiation is occasionally cited by an employee as a cause of physical injury. NOTE For specific requirements and limitations, refer to FAA Advisory Circular 20–68B, Recommended Radiation Safety Precautions for Ground Operation of Airborne Weather Radar.

7.3 Spoki ng : This section addresses reports of “spoking” interference 7.3 that have been reported by operators, particularly when operating in regions where military training activities are being conducted. This interference is temporary and is not a failure of the radar and should not be a cause for removal of the radar equipment.

The MultiScan radar incorporates a sophisticated alien radar rejection algorithm that is designed to prevent interference from other airborne 74

weather radars. However, some external interference sources such as military jamming equipment can produce spoking or other display effects that cannot be rejected. One example of this interference is shown in the following image. The spoke in the picture to the right is caused by a military CW jammer that has “burned through” the alien radar rejection software.

Spoking caused by a military  jammer 

The interference is displayed as a radial spoke in the direction of the interference source as the radar antenna sweeps past the interfering signal. This type of of interference interference can be readily identified since it appears to emanate from the apex of the display and extends generally to the outer edge of the the display regardless of the selected selected range. The direction of the spoke is toward the interfering source. source. The interfering source may be either ground based or airborne and thus the direction of the spoke may change as the interfering source changes position or as the aircraft moves or changes changes heading. The displayed interference will persist persist for as long as the the interfering source source is present. This interference does not damage the radar equipment and once the interference is removed, the display will clear up within a few sweeps. The intensity of the spoke can vary widely from a barely perceptible green up to a strong red/yellow/green return depending on the strength of interfering signal. The interference interference can also trigger trigger a magenta magenta turbulence indication or even trigger an Associated Threat speckled icon for newer ThreatT ThreatTrack rack systems. Additional examples of spoking including turbulence and Associated Threat effects are shown in the images that follow. 75

 Auto Mode showing a green “spoke” return along the aircraft heading

 Auto Mode showing a spoke with turbulence indication out to 40 NM.

Manual Mode showing spoke with turbulence indication out to 40 NM.

Manual Mode with radial spoke extending through a Military Restricted  Area.

ThreatTrack Auto Mode showing spoke with turbulence indication and Associated Threat speckled pattern.

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The Sun is also a very strong microwave emitter and can produce a similar spoking effect if the antenna sweeps directly past the sun. Notice that the energy of the sun in line with the aircraft heading during sunrise has also created a spoke, albeit of less intensity.

7.4 V1 Differences 7.4.1 Blo omi ng : There is a nuisance condition in the V1 software that is associated with the OverFlight Protection feature (see Section 5.2.1). On occasion a weather return may suddenly increase in intensity or “Bloom” across the aircraft flight path, generally within 7 to 10 NM in front of the aircraft. Blooming to green or yellow means that there is some low level activity somewhere beneath the aircraft and the aircraft will experience light to moderate chop. If the cell blooms to red the aircraft may experience severe turbulence. This may be a cell growing into the aircraft flight path that shows up in the beam at the last minute. Cells can grow as rapidly as 6,000 ft/min and come up and hit the aircraft beneath the radar beam. With MultiScan ThreatTrack the Predictive OverFlight feature is designed to protect against these type of events (see Section 3.3.1.2).

 Aircraft clear to pass to left of cell

Blooming at 7 NM

 A nuisance alert consisting of weather blooming in front of the aircraft at 7-10 NM is a result of an error in the V1 software. As long as the return blooms only to green or yellow it indicates weather that is below the aircraft attitude and light to moderate chop would be expected.

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