Garmin GTN 625, Flight Manual

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190-01007-A2 Rev. 6 AFMS, Garmin GTN GPS/SBAS System
Page 20 FAA APPROVED
3.2 Abnormal Procedures
3.2.1 LOSS OF GPS/SBAS NAVIGATION DATA
When the GPS/SBAS receiver is inoperative or GPS navigation information is
not available or invalid, the GTN will enter one of two modes: Dead Reckoning
mode (DR) or Loss Of Integrity mode (LOI). The mode is indicated on the GTN
by an amber “DR” or “LOI”.
If the LOI annunciation is displayed, revert to an alternate means of navigation
appropriate to the route and phase of flight.
If the DR annunciation is displayed, the map will continue to be displayed with
an amber “DR” overwriting the ownship icon. Course guidance will be removed
on the CDI. Aircraft position will be based upon the last valid GPS position,
then estimated by Dead Reckoning methods. Changes in true airspeed, altitude,
heading, or winds aloft can affect the estimated position substantially. Dead
Reckoning is only available in Enroute and Oceanic modes. Terminal and
Approach modes do not support Dead Reckoning.
If Alternate Navigation Sources (ILS, LOC, VOR, DME, ADF) Are
Available:
Navigation ......................................................... USE ALTERNATE SOURCES
If No Alternate Navigation Sources Are Available:
DEAD RECKONING (DR) MODE:
Navigation ............................................................................................. USE GTN
NOTE
All information normally derived from GPS will become less
accurate over time.
LOSS OF INTEGRITY (LOI) MODE:
Navigation ..................... FLY TOWARDS KNOWN VISUAL CONDITIONS
NOTE
All information derived from GPS will be removed.
NOTE
The airplane symbol is removed from all maps. The map will
remain centered at the last
known position. “NO GPS
POSITION” will be annunciated in the center of the map.