Garmin Flight Deck 100 Manual

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190-00728-04 Rev. A

Embraer Prodigy

Flight Deck 100 Pilot’s Guide

357

HAZARD AVOIDANCE

6.2 AIRBORNE COLOR WEATHER RADAR

SYSTEM DESCRIPTION

The GarminGWX 68Airborne ColorWeather Radaris a4-color digitalpulsed radarwith 6.5kilowatts

ofoutputpower.Itcombinesexcellentrangeandadjustablescanningproleswithahigh-denitiontarget

display.Thepulsewidthisfourmicroseconds(µs)onallrangesexceptthe2.5nmrange.TheGWX68usesa

oneµspulsewidthatthisrangetoreducethetargetssmearingtogetheronthedisplayforbettertargetdenition

at close range.

TheEmbraerPhenom100usesa12-inchphasedarrayantennathatisfullystabilizedtoaccommodate30º

of pitch and roll.

Tofocusradarscanningonspecicareas,SectorScanningofferspilot-adjustablehorizontalscananglesof

20º,40º,60º,or90º.Averticalscanningfunctionhelpstoanalyzestormtops,gradients,andcellbuildup

activity at various altitudes.

Radarfeaturesinclude:

•ExtendedSensitivityTimeConstant(STC)logicthatautomaticallycorrelatesdistanceofthereturnechowith

intensity, so cells do not suddenly appear to get larger as they get closer.

•WATCH

(WeatherATtenuatedColorHighlight)helpsidentifypossibleshadowingeffectsofshort-rangecell

activity,identifyingareaswhereradarreturnsignalsareweakenedorattenuatedbyintenseprecipitation(or

largeareasoflesserprecipitation)andmaynotfullyreecttheweatherbehindastorm.

•WeatherAlertthatlooksaheadforintensecellactivityinthe80-320nmrange,eveniftheserangesarenot

being monitored.

PRINCIPLES OF PULSED AIRBORNE WEATHER RADAR

ThetermRADARisanacronymforRAdioDetectingAndRanging.Pulsedradarlocatestargetsbytransmitting

a microwave pulse beam that, upon encountering a target, is reﬂected back to the radar receiver as a return

echo.Themicrowavepulsesarefocusedandradiatedbytheantenna,withthemostintenseenergyinthe

centerofthebeamanddecreasingintensityneartheedge.Thesameantennaisusedforbothtransmittingand

receiving.ThereturnedsignalisthenprocessedanddisplayedontheMFD.

Radardetectionisatwo-wayprocessthatrequires12.36µsforthetransmittedmicrowavepulsestotravelout

andbackforeachnauticalmileoftargetrange.Ittakes123.6µsforatransmittedpulsetomaketheroundtrip

if a target is ten nautical miles away.

Airborneweather radarshouldbe usedtoavoidsevereweather,notfor penetratingsevereweather.The

decision to ﬂy into an area of radar targets depends on target intensity, spacing between the targets, aircraft

capabilities,andpilotexperience.Pulsetypeweatherradardetectsonlyprecipitation,notcloudsorturbulence.

Thedisplaymayindicateclearareasbetweenintensereturns,butthisdoesnotnecessarilymeanitissafetoy

betweenthem.OnlyDopplerradarcandetectturbulence.

Airborneweatherradarhasothercapabilitiesbeyondweatherdetection.Italsohastheabilitytodetectand

provide distance to cities, mountains, coastlines, rivers, lakes, and oceans.