Embraer Prodigy® Flight Deck 100 Pilot’s Guide
190-00728-04 Rev. A
360
HAZARD AVOIDANCE
Figure 6-52 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 reflected 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.