Weather Mapping And Interpretation - Garmin G950 Pilot's Manual

HAZARD AVOIDANCE
If the aircraft is above 29,000 feet, be cautious of any target return that gets to within 30 nautical miles.
This is likely a thunderstorm that has a top high enough that the aircraft cannot fly over it safely.
If the aircraft altitude is 15,000 feet or lower, setting the displayed range to 60 miles may be more helpful.
Closely monitor anything that enters the display.
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.
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. If that ground target
return moves to five nm, maximum distance below the aircraft is 2,000 feet.
This setup provides a good starting point for practical use of the weather radar. 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 6-1.
296
Change in Antenna Tilt
Figure 6-6 Vertical Change in Radar Beam per Nautical Mile
Weather Mode Color
Black
Green 23 dBZ to < 32 dBZ
Yellow 32 dBZ to < 41 dBZ
Red
41 dBZ to < 50 dBZ
Magenta
50 dBZ and greater
Table 6-1 Precipitation Intensity Levels
Garmin G950 Pilot's Guide for the Pilatus PC-6
+4°
+3°
+2°
+1°
0°
-1°
-2°
-3°
-4°
10 nm
Approximate
Intensity
Precipitation Rate
(in/hr.)
< 23 dBZ < .01.
.01 - 0.1.
0.1 - 0.5
0.5 - 2
> 2
4000
3000
2000
1000
0
1000
2000
3000
4000
190-00870-02 Rev. A