
Garmin G1000 Cockpit Reference Guide for the Cessna Caravan
190-00748-05 Rev. A 63
Abnormal Operation
Flight
Instruments EIS
Nav/Com/
XPDR/Audio AFCS GPS Nav
Flight
Planning Procedures
Hazard
Avoidance
Additional
Features
Abnormal
Operation
Annun/
Alerts Appendix Index
DEAD RECKONING
WhileinEnrouteorOceanicphaseofight,iftheG1000detectsaninvalidGPS
solutionorisunabletocalculateaGPSposition,thesystemautomaticallyrevertsto
DeadReckoning(DR)Mode.InDRMode,theG1000usesitslast-knownposition
combinedwithcontinuouslyupdatedairspeedandheadingdata(whenavailable)to
calculateanddisplaytheaircraft’scurrentestimatedposition.
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 the following
gure.Inaddition,‘DR’isprominentlydisplayed,alsoinyellow,ontheHSIslightly
aboveandtotherightoftheaircraftsymbolontheCDIasshowninthefollowing
gure.TheCDIdeviationbarisdisplayedinyellow,butwillberemovedfromthe
displayafter20minutes.Lastly,butatthesametime,a‘GPSNAVLOST’alertmessage
appearsonthePFD.
NormalnavigationusingGPS/SBASsourcedataresumesautomaticallyonceavalid
GPSsolutionisrestored.
ItisimportanttonotethatestimatednavigationdatasuppliedbytheG1000in
DRModemaybecomeincreasinglyunreliableandmustnotbeusedasasolemeans
of navigation. If, while in DR Mode, airspeed and/or heading data is also lost or
notavailable,theDRfunctionmaynotbecapableofestimatingyourpositionand,
consequently,thesystemmaydisplayapaththatisdifferentthantheactualmovement
of the aircraft. Estimated position information displayed by the G1000 through
DRwhilethereisnoheadingand/orairspeeddataavailableshouldnotbeusedfor
navigation.
DRModeisinherentlylessaccuratethanthestandardGPS/SBASModeduetothe
lackofsatellitemeasurementsneededtodetermineaposition.Changesinwindspeed
and/orwinddirectioncompoundstherelativeinaccuracyofDRMode.Becauseofthis
degradedaccuracy,thecrewmustmaintainpositionawarenessusingothernavigation
equipmentuntilGPS-derivedpositiondataisrestored.
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