Manualshelf

Pilot's Guide

ManualsBrandsGarmin ManualsFlight DecksGarmin MDL Rev 8, SA01456Wi_D
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Garmin G1000 Pilot’s Guide for the Hawker Beechcraft C90A/GT/GTi
190-00663-02 Rev. B332
HAZARD AVOIDANCE
Figure 6-55 Precipitation Type and Reflectivity
groUnD retUrns
The intensity of ground target returns depends upon the angle at which the radar beam strikes the
groundtarget(AngleofIncidence)andthereectivepropertiesofthattarget.Thegaincanbeadjustedso
shorelines,rivers,lakes,andcitiesarewell-dened.Increasingthegaintoomuchcausesthedisplaytoll
inbetweentargets,thusobscuringsomelandmarks.
Citiesnormallyprovideastrongreturnsignal.Whilelargebuildingsandstructuresprovidegoodreturns,
smallbuildingscanbeshadowedfromtheradarbeambythetallerbuildings.Astheaircraftapproaches
and shorter ranges are selected, details become more noticeable as the highly reflective regular lines and
edges of the city become more defined.
Bodiesofwatersuchaslakes,rivers,andoceansarenotgoodreectorsandnormallydonotprovidegood
returns.Theenergyisreectedinaforwardscatteranglewithinadequateenergybeingreturned.They
canappearasdarkareasonthedisplay.However,roughorchoppywaterisabetterreectorandprovides
stronger returns from the downwind sides of the waves.
Mountainsalsoprovidestrongreturnsignalstotheantenna,butalsoblocktheareasbehind.However,
overmountainousterrain,theradarbeamcanbereectedbackandforthinthemountainpassesoroff
canyonwalls,usingupallormostoftheradarenergy.Inthiscase,noreturnsignalisreceivedfromthis
area,causingthedisplaytoshowadarkspotwhichcouldindicateapasswherenopassexists.
angle of inciDence
TheangleatwhichtheradarbeamstrikesthetargetiscalledtheAngleofIncidence.Thegureillustrates
theincidentangle(‘A’).Thisdirectlyaffectsthedetectablerange,theareaofillumination,andtheintensity
ofthedisplayedtargetreturns.Alargeincidentanglegivestheradarsystemasmallerdetectablerangeand
lower display intensity due to minimized reflection of the radar energy.