Pilot's Guide

190-00663-02 Rev. B
Garmin G1000 Pilot’s Guide for the Hawker Beechcraft C90A/GT/GTi
335
HAZARD AVOIDANCE
Also,aftersettinguptheantennatiltangleasdescribedpreviously,groundreturnscanbemonitoredforpossible
threats.Therelationshipbetweenantennatiltangle,altitude,anddistanceisonedegreeoftiltequals100feetof
altitude for every one nautical mile.
Vertical Change of Radar Beam (feet)
Change in Antenna Tilt
10 nm
0
1000
2000
3000
4000
1000
2000
3000
4000
-1°
0°
-2°
-3°
-4°
+1°
+2°
+3°
+4°
Figure 6-58 Vertical Change in Radar Beam per Nautical Mile
Therefore,withthe antennatilt setso thatthe bottomof thebeamisfourdegreesbelow parallelwith
theground,atargetreturnat10nmisapproximately4,000feetbelowtheaircraft;at20nm,8,000feet;
at50nm,20,000feet.Inotherwords,atthistiltsetting,agroundreturn(suchasamountainpeak)being
displayedat10nmwouldhaveamaximumdistancebelowtheaircraftof4,000feet.Whenthegroundtarget
returnmovesto5nm,maximumdistancebelowtheaircraftis2,000feet.
ThissetupprovidesagoodstartingpointforpracticaluseoftheGWX68.Therearemanyotherfactorsto
consider in order to become proficient at using weather radar in all situations.
WEATHER MAPPING AND INTERPRETATION
WEATHER DISPLAY INTERPRETATION
Whenevaluatingvarioustargetreturnsontheweatherradardisplay,thecolorsdenoteprecipitationintensity
and rates shown in the table.
Weather Mode Color Intensity
Approximate
Precipitation Rate
(in/hr.)
Black < 23 dBZ < .01.
Green 23 dBZ to < 32 dBZ .01 - 0.1.
Yellow 32 dBZ to < 41 dBZ 0.1 - 0.5
Red 41 dBZ to < 50 dBZ 0.5 - 2
Magenta 50 dBZ and greater > 2
Table 6-4 Precipitation Intensity Levels