Pilot's Guide

Garmin G1000 Pilot’s Guide for the Hawker Beechcraft C90A/GT/GTi
190-00663-02 Rev. B354
HAZARD AVOIDANCE
6.4 TAWS-B
WARNING: Do not use TAWS-B information for primary terrain avoidance. TAWS-B is intended only to
enhance situational awareness.
NOTE: Terrain data is not displayed if the aircraft is out of the installed terrain database coverage area.
NOTE: The data contained in the TAWS-B databases comes from government agencies. Garmin accurately
processes and cross-validates the data, but cannot guarantee the accuracy and completeness of the data.
NOTE: Government agencies provide the terrain data used in TAWS-B databases, which may contain
inaccuracies or omissions. Garmin processes this data to ensure the integrity of the databases, but cannot
guarantee the accuracy and completeness of the terrain data.
TAWS-B(TerrainAwarenessandWarningSystem-ClassB)isanoptionalfeaturetoincreasesituationalawareness
andaidinreducingcontrolledightintoterrain(CFIT).TAWS-Bprovidesvisualandauralannunciationswhen
terrainandobstaclesarewithinthegivenaltitudethresholdfromtheaircraft.Thedisplayedalertsandwarnings
are advisory in nature only.
TAWS-BsatisesTSO-C151bClassBrequirementsforcertication.
TAWS-Brequiresthefollowingtooperateproperly:
•Avalidterrain/obstacle/airportterraindatabase
•Avalid3-DGPSpositionsolution
TAWS-Busesterrainandobstacleinformationsuppliedbygovernmentsources.Terraininformationisbased
onterrainelevationinformationinadatabasethatmaycontaininaccuracies.Individualobstructionsmaybe
shownifavailableinthedatabase.Garminveriesthedatatoconrmaccuracyofthecontent,perTSO-C151b.
However,thedisplayedinformationshouldneverbeunderstoodasbeingall-inclusiveanddatamaybeinaccurate.
TAWS-BusesinformationprovidedfromtheGPSreceivertoprovideahorizontalpositionandaltitude.GPS
altitudeisderivedfromsatellitemeasurements.GPSaltitudeisthenconvertedtotheheightabovegeodetic sea
level(GSL),whichistheheightabovemeansealevel(MSL)calculatedgeometrically.GSLaltitudeisusedto
determineTAWS-Balerts.GSLaltitudeaccuracyisaffectedbysatellitegeometry,butisnotsubjecttovariations
inpressureandtemperaturethatnormallyaffectpressurealtitudesensors.GSLaltitudedoesnotrequirelocal
altimetersettingstodetermineMSLaltitude.Itisawidely-usedMSLaltitudesource.Therefore,GSLaltitude
providesahighlyaccurateandreliableMSLaltitudesourcetocalculateterrainandobstaclealerts.
TheterrainandobstacledatabasesusedbyTAWS-BarereferencedtoMSL.UsingtheGPSpositionandGSL
altitude,TAWS-Bdisplays a2-Dpictureof thesurroundingterrainandobstaclesrelativetothe positionand
altitudeoftheaircraft.Furthermore,theGPSpositionandGSLaltitudeareusedtocalculateand“predict”the
aircraft’sightpathinrelationtothesurroundingterrainandobstacles.Inthismanner,TAWS-Bcanprovide
advanced alerts of predicted dangerous terrain conditions.
Baro-correctedaltitude(orindicatedaltitude)isderivedbyadjustingthealtimetersettingforlocalatmospheric
conditions.  The most accurate baro-corrected altitude can be achieved by frequently updating the altimeter
setting to the nearest reporting station along the flight path. However, because actual atmospheric conditions
seldommatchthestandardconditionsdenedbytheInternationalStandardAtmosphere(ISA)model(where