190-00728-04 Rev. A
Embraer Prodigy® Flight Deck 100 Pilot’s Guide
393
HAZARD AVOIDANCE
ClassATAWSincorporatesradaraltimeterinputwiththeGPS-GSLaltitudetoprovideamoreaccurateposition
referencewhenatloweraltitudesforcertainalerttypes,andtoretainalevelofgroundproximitywarningcapability
in the unlikely event of an airport, terrain or obstacle database failure.
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Inter nationalStandardAtmosphere(ISA)model(wherepressure,
temperature,andlapserates havexedvalues), itiscommon forthebaro-correctedaltitude (asreadfrom the
altimeter)todifferfromtheGPS-MSLaltitude.Thisvariation resultsintheaircraft’struealtitudedifferingfrom
thebaro-correctedaltitude.
TAWS-Aprovidesthefollowingalerttypes:
•ForwardLookingTerrainAvoidance(FLTA)Alerting,whichconsistsof:
  •RequiredTerrainClearance(RTC)/RequiredObstacleClearance(ROC)Alerting
  •ImminentTerrainImpact(ITI)/ImminentObstacleImpact(IOI)Alerting
•PrematureDescentAlerting(PDA)
•GroundProximityWarningSystem(GPWS)Alerting,whichconsistsof:
 •ExcessiveDescentRate(EDR)Alerting
 •ExcessiveClosureRate(ECR)toTerrainAlerting
 •FlightIntoTerrain(FIT)Alerting
 •NegativeClimbRate(NCR)aftertakeoffAlerting
 •ExcessivebelowGlideslope/GlidepathDeviation(GSD)Alerting
 •AltitudeVoiceCallOut(VCO)Alerting
DISPLAYING TAWS-A DATA
TAWS-Ausesyellow(caution)andred(warning) todepictterrainandobstacles (withheightsgreaterthan
200feetabovegroundlevel,AGL) alertsrelativetoaircraftaltitude. Colorsareadjustedautomatically asthe
aircraftaltitudechanges.Thecolors andsymbolsinFigure6-87 andTable6-9areusedtorepresent terrain,
obstacles, and potential impact points.
Figure 6-87 Terrain Altitude/Color Correlation for TAWS-A