User Guide

Garmin G1000 Cockpit Reference Guide for the Cessna Citation Mustang
190-00600-00 Rev. B
47
Abnormal Operation
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’ superim-
posed in yellow over the ‘own aircraft’ symbol as shown in Figure 11-4. 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 Figure 11-4. Also, the CDI devia-
tion 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.