,
I
i
:L,
I
bedn apl;rroved as JAA compliant by the UnJted Kingdom Civil AviatSon Authority.
I learning rnateP'falhas
was then displayed as latitude and long left or right of track, in nautical miles. A Doppler navigation system:
The latest improved Doppler Na
Navigation Systems, caused by inaccurate heading reference and de and drift when flying over large expanses of water. principle is also utilized in other navigation systems,
RADIO NAVIGATION
DOPPLER RADAR
Figure 2.7. The Racal RNS 252 Navigation Computer Unit.
n O Oxford Aviation Services L~mited
F EMERGENCY SERVI
his service is available at 3,00
QUESTION
ANSWER
1
C
2
B
3
B
4
C
5
C
6
A
USE KR 87 TSO
w
STBY
I
SAY 30" TO lEGAlN TRACK
NIRCRAFT ON TRA WHEN RELATIVE \RING BECOMI
:AUINCi AL iER
TO MAINTAIN U C K ALLOWING R IilOPnRTi3RlFT
BFO on for tuning
FACTORS AFF
VOR BEACON ACCURAC
Site error is caused by uneven terrain such as hills and man-m course-displacement error'. Ground VOR beacon site error is monitored to h lo accurac Propagation error is caused by the fact that, having left the VOR site with flo accurac
E CONE OF AMBIGUI the VOR is approached the
at the aircraft (regardless of its heading) is displaced to the right of a magnetic track of
tion must be applied.
QDM of 090" and subtracts the positions the RMI needle 50" clo
of 040" to give a relative bearing of 050°W from the heading index. (If there were a differe
+ 050" = 090°, which is the correct QDM to the VOR based on the magnetic meridian a beacon. Compare this with the case of an ADF bearing displayed by RMI, where the mag
A single channel VHF carrier wave a being frequency modulated at 30 Hz
e accuracy, res hoes are assesse
scent; turn left 3 " , h e until 4nm to go; ther
-2 % MILES approx 3 % and 2
checks Positioning instructions, weather information, Airfield
fI
n. If there is water in the antenna radome or ice on the outside of it, the energy absorbed wi se the water to evaporate and the ice to melt. This means that less energy is transmitted in t
flashing display of the areas associated with turbulence. There may also be available a Con Intensity control to enable adjustment of the display for optimum presentation. The latest A
I
ON
ALT TST IDENT
w KING KT76L
RMT
K
OFF
w KING
FREQ
-
GSlT
BEACON
Aircraft Interrogation
Beacon Transponds
Military Aircraft Select
Civil Aircraft Select
MAZ Tacan
1131 MHz
1194MHz
Channel l07X
116.0MHz
OX DME
1148MHz
1211MHz
Channel l24X
117.7MHz
igure 12.9. Acceptance of Own Pulse
12.8
STATION IDENTIFICATION
the ident period. However the aircraft equipment has a 10 second memory circuit to co displaying the range obtained. The DME identification is distinguished from the
ay be frequency paired with a DME, or a military TACAN installation. This means that the
THERE ARE FOUR IDENTS' EVERY 30
VOIUDME-TACAN WIDELY SEPARATED i.e. >6nm
I I
r
!N"
1 ,
m m - n
1 1 WPT
>
-
- - '
l
4
DST
I
accuracy of the external reference (see paragraph 13.16). If the FMS is using just the rmation to derive position a warning is displayed to the crew indicating the positio rmation is downgraded.
RADIO NAVIGATION
aerodrome designator held in the database, if the ICAO identifier was input on the , then it will appear at IL. The company route is inserted at 2L and the flight number a e runway in use and the SID and first route waypoint are inserted at 3L and 4L, note this 5R (next reporting point on airway V2) is inserted by the computer from the database.
ves up to line 3 and the next waypoint appears at 4. As an active waypoint is passed line thr cleared and re
index profile and inform the pilots of the power, speed and configuration to achieve the requir profile. If the manual input of a route is required; this can be achieved through the scratchpa
Latitude and Longitude as either a 7 group alphanumeric (eg. N05W010) or a 15 group (e N0926.3W00504.7), note the leading zeros must be entered for the FMC to accept the positio
RADIO NAVIGATION 13.13
DESCENT
sition and altitude, the suffix A indicates at or above.. Position 3L contains the spe sition, which is 10 kt less than that stored in the database, and the transition altitude, if no
undspeed and rate of descent. V/B is the vertical bearing ie the FPA required to achieve th
IN IRS, TWIN FM 1 normally receive info right FMC from the right IRS. The systems compare the IRS positions but if there i discrepancy, cannot determine, in isolation which system is in error. The FMC must have input of an external reference in order to determine the correct position. Using Kalman filteri the external reference is compared with the IRS positions to determine the system position. the start of a flight the IRS position will predominate but as the flight progresses, the I positions will degrade and the weighting for the external reference will increase, comrnensur with the selection of external reference, and the range from that reference (see 13.15 and 13.1
esigningelectronic horizonta
ANDED VOR
e expanded VOR mode
heading - box indicates actual heading. Referenced to Magnetic (M) or true (TRU) North.
selected IRS (360deg available but approximately 70deg are displayed
osition at the centre of
aircraft is currently navigating to. Downpath - Represents a navigation
RADIO NAVIGATION
APPENDIX A
HDG
O Oxford Aviation Services Limited
[-]
[-I
[-I
GPS
["I:' "I:'[
[-]
I':"'[F]F]
NAVIGATION SYSTEM
ame 1 contains SV clock error, frames 2 and 3 contain the SV ephemeris data, frame ntains data on the ionospheric propagation model, GPS time and its correlation with UT
valid from 4 hours to several months dependent on the type of receiver.
t takes 12.5 minutes to download from the SVs. When the receiver position is significantly 1
ill be obtained within about 30 seconds. If any are missing then the time to first fix will be
The receiver has to correct the X, Y, Z coordinates and time to produce the fix. Since it has ea element provided by each S 4 unknown quantities (X, Y, Z, and T) which it solves by iteration to remove the receiver ti error, and hence, range err accurate time reference, ie transposed into latitude and Survey grid) and altitude.
of altitude, the altitude simulates a fourth SV positione position produced will not be as accurate as the 4D fix.
gravitational effects of the sun, moon and planets and solar radiation. As discussed in 15.6 t SV position is checked even, 12 hours and, where necessarv, updated. The maximum error w
SV Clock Error. As with SV ephemeris, the SV clock is checked at least every 12 hours a .5 m. any error passed to the SV to be included in the broadcast. Maxi Ionospheric propagation error. The ionosphere affects radio waves of all frequencies, t actual effect being dependent on the frequency. The SV broadcast contains a model o f t ionosphere which is used to make time corrections to the measured time interval. The state the ionosphere is continuously checked at the monitoring stations and the model is u~datedt the SVs at least every 12 hour This is the most significant of If two different frequencies ar transit of the signals and minimising the error. rror for single frequency o
the effect of variations in tropospheric conditions on the passage of radio waves has beco significant. Variations in pressure, temperature, density and humidity affect the speed propagation, for example a change in transit time of one nanosecond would give an error of 0 m. Maximum 0.5 m. As wi
eceivers can cause errors in measurement of the time difference. Maximum 0.3 m
NAVIGATION SYSTEMS
GLOBAL NAVIGATION SATELLITE SYSTEM
USA withdrew SA at 0000 on 01 May 2000, and President Clinton stated that it would neve reintroduced. (SA downgraded the accuracy of position derived from the CIA code to the or
SYSTEM ACCURACY
precision systems (eg L S ) and 8 second warning for non-precision systems. With 4 SVs bei any of the SV data and an operator could potentially experience errors of hundreds of mil unless he was able to cross check the GNSS position with another system. Therefore differenti
15.12 DIFFERENTIAL GPS (DGPS)
If the SV information degrades, the GPS receiver has no means of determining the degradatio Consequentially the safety of flight may be seriously endangered. DGPS is a means of any errors which occur. DGPS systems will provide warning of failure in the SV data prevent or minimize the effect of such errors, or provide failure warning and improve
ir based augmentation systems (ABAS)
NAVIGATION SYSTEM
operational SVs to achieve continuous global availability. RAIM will only provide fail
oise and rnulti-path reception as these errors are particular to the receiver. It is specifics blished to provide precision runway approaches
ta and either correct the error or give a failure warning indication.
RADIO NAVIGATION
ifferential range by phase comparison. n practice the master and slaves cannot
mparison cannot take place unless each
ster and slaves of a chain each
multiple of the chain's allocated ever transmitted.
se to 14kHz. The transmitters thus nsmit fixed harmonics off
undamental Frequenc
