
Garmin G1000 Cockpit Reference Guide for the Socata TBM 850
190-00708-00 Rev. A
SECTION 12 – ABNORMAL
OPERATION
12-3
uses its last-known position combined with continuously
updated airspeed and heading data (when available) to
calculate and display the aircraft’s current estimated
position.
NOTE: Dead Reckoning Mode only functions in
Enroute (ENR) or Oceanic (OCN) phase of flight.
In all other phases, an invalid GPS solution
produces a “NO GPS POSITION” annunciation
on the map and the G1000 stops navigating in
GPS Mode.
DR Mode is indicated on the G1000 by the appearance
of the letters ‘DR’ superimposed in yellow over the ‘own
aircraft’ symbol as shown in Figure 12-4. In addition,
‘DR’ is prominently displayed, also in yellow, on the HSI
slightly above and to the right of the aircraft symbol on the
CDI as shown in Figure 12-4. Also, the CDI deviation bar
is removed from the display. Lastly, but at the same time,
a ‘GPS NAV LOST’ alert message appears on the PFD.
Normal navigation using GPS/WAAS source data
will resume automatically once a valid GPS solution is
restored.
It is important to note that estimated navigation
data supplied by the G1000 in DR Mode may become
increasingly unreliable and must not be used as a sole
means of navigation. If, while in DR Mode, airspeed and/
or heading data is also lost or not available, the DR function
may not be capable of accurately tracking your estimated
position and, consequently, the system may display a path
that is different than the actual movement of the aircraft.
Estimated position information displayed by the G1000
through DR while there is no heading and/or airspeed
data available should not be used for navigation.
Figure 12-4 Dead Reckoning Indications
Symbolic Aircraft
(Map pages and Inset Map)
CDI ‘DR’ Indication on PFD
As a result of operating in DR Mode, all GPS-derived
data is computed based upon an estimated position and is
displayed as yellow text on the display to denote degraded
navigation source information. This data includes the
following:
• Navigation Status Box fields except Active Leg, TAS,
and DTK
• GPS Bearing Pointer
• Wind data and pointers in the Wind Data Box on
the PFD and MFD
• Track Bug
• All Bearing Pointer Distances
• Active Flight Plan distances, bearings, and ETE
values
Also, while the G1000 is in DR Mode, the autopilot
will not couple to GPS, and both TAWS and Terrain
Proximity is disabled. Additionally, the accuracy of all
nearest information (airports, airspaces, and waypoints) is
questionable. Finally, airspace alerts continue to function,
but with degraded accuracy.
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