Doppler has completed Built in Test (BIT) and is operating satisfactorily,
GPS is still performing BIT (GPS has 2 minute BIT cycle maximum).
Note that a rotating bar in the display indicates that the GPS is still per-
forming self test.
The entire system has completed BIT and is operating satisfactorily.
Pitch or Roll data is missing or exceeds 90_. In this case, pitch and roll in
the computer are both set to zero and navigation in the Doppler mode
continues with degrade operation. Problem may be in the vertical gyro or
C, R, S, or H fol-
lowed by a nu-
A failure has occurred in the Computer Display Unit or the Signal Data
Converter Power Supply. The operator should not use the system.
GPS failure code
GPS has failed but operator can use doppler to perform all navigation.
Doppler has failed. GPS is still performing self test.
Doppler has failed but operator can use GPS to perform all navigation.
e. Procedure for Displaying or Selecting GPS M or Y
Operating Mode, Doppler, GPS, or Combined Operation,
and Displaying Groundspeed and Track.
Set MODE switch to MGRS position (LAT/
LONG or GPS LDG position may also be used).
Set DISPLAY switch to GS/TK/NAV M.
The display indicates the current GPS and
navigation mode on the top line:
Selected Fly to waypoint.
EPE (GPS Estimated Position Error in
Meters. An asterisk (*) in the character position of the
EPE display indicates an EPE of greater than 999 or data
GPS mode of operation:
M for mixed C\A and P/Y code GPS reception
Y for only Y code GPS reception.
DGNS mode of operation:
C for combined Doppler and GPS
D for Doppler only
G for GPS only
R for remembered velocities
* for no navigation.
Target destination where the present
position will be stored next time TGT/STR is depressed.
In MGRS mode, ground speed is displayed in
km/hr; in LAT/LONG mode, ground speed is
displayed in knots.
Only mode C, G, and D may be selected as
the primary navigation mode. Modes R and *
are automatic fall back modes used when
both the Doppler and GPS are unavailable.
Selection of GPS mode of operation:
As an example, consider selection of Y-only mode. De-
press KYBD key. Observe that the GPS mode blinks. To
enter Y (for Y mode) depress key LTR LEFT followed by
key 9. A Y will be displayed. Depress ENT key. The entire
display will blank out for less than one second and the
center display will now indicate: Y.
Selection of DGNS mode of operation.
As an example, consider selection of GPS-only mode of
operation. Depress KYBD key twice. Observe that the
DGNS mode blinks. To enter G (for GPS mode) depress
key LTR LEFT followed by key 3. A G will be displayed.
Depress ENT key. The entire display will blank out less
than one second and the DGNS Mode will now indicate:
G (or * if GPS is not available).
Ground Speed and Ground Track Angle are
displayed on lines 3 and 4.
f. Procedure for Entering/Displaying Present posi-
tion or One of the 100 Possible Destinations in MGRS.
The DGNS has the capability to display 100 destinations
(numbered 00 through 99).
-00 to 69
-70 to 89
Data Load-only Waypoints, Ob-
servable but not changeable via
CDU keyboard. Used for Nation-
al Airspace Data Such as VORs,
NDBs and intersections.
-90 to 99
Target Store Waypoints (Usable
as Standard Waypoints)