Dead Reckoning - Garmin G1000 Cockpit Reference Manual

DEAD RECKONING

While in Enroute or Oceanic phase of flight, if the G1000 detects an invalid GPS
solution or is unable to calculate a GPS position, the system will automatically revert
to Dead Reckoning (DR) Mode. In DR Mode, the G1000 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 will only function in Enroute (ENR) or Oceanic
(OCN) phase of flight. In all other phases, an invalid GPS solution will produce
a "NO GPS POSITION" annunciation on the map and the G1000 will stop
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 the following
figure. In addition, 'DR' will be prominently displayed, also in yellow, on the HSI
slightly above and to the right of the aircraft symbol on the CDI as shown in the
following figure. Also, the CDI deviation bar is removed from the display. Lastly, but
at the same time, a 'GPS NAV LOST' alert message will appear 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.
DR Mode is inherently less accurate than the standard GPS/WAAS Mode due to the
lack of satellite measurements needed to determine a position. Changes in wind speed
and/or wind direction will compound the relative inaccuracy of DR Mode. Because
of this degraded accuracy, the crew must maintain position awareness using other
navigation equipment until GPS-derived position data is restored.
190-00600-01 Rev. C Garmin G1000 Cockpit Reference Guide for the Cessna Citation Mustang
Abnormal Operation
53