PRIMUSr 880 Digital Weather Radar System
Airborne weather avoidance radar is, as its name implies, for avoiding severe weather - not for penetrating it. Whether to fly into an area of radar echoes depends on echo intensity, spacing between the echoes, and the capabilities of you and your aircraft. Remember that weather radar detects only precipitation drops; it does not detect turbulence. Therefore, the radar scope provides no assurance of avoidance turbulence. The radar scope also does not provide assurance of avoiding instrument weather from clouds and fog. Your scope may be clear between intense echoes; this clear does not mean you can fly.
Remember that while hail always gives a radar echo, it may fall several miles from the nearest cloud and hazardous turbulence may extend to as much as 20 miles from the echo edge. Avoid intense or extreme level echoes by at least 20 miles; that is, such echoes should be separated by at least 40 miles before you fly between them. With weaker echoes you can reduce the distance by which you avoid them.
DO’S AND DON’TS OF THUNDERSTORM FLYING
Above all, remember this: Never regard any thunderstorm lightly even when radar observers report the echoes are of light intensity. Avoiding thunderstorms is the best policy. Following are some do’s and don’ts of thunderstorm avoidance:
DDon’t land or take off in the face of an approaching thunderstorm. A sudden gust front of low level turbulence could cause loss of control.
DDon’t attempt to fly under a thunderstorm even if you can see through to the other side. Turbulence and wind shear under the storm could be disastrous.
DDon’t fly without airborne radar into a cloud mass containing scattered embedded thunderstorms. Scattered thunderstorms not embedded, usually can be visually circumnavigated.
DDon’t trust the visual appearance to be a reliable indicator of the turbulence inside a thunderstorm.
DDo avoid, by at least 20 miles, any thunderstorm identified as severe or giving an intense radar echo. This is especially true under the anvil of a large cumulonimbus.
DDo circumnavigate the entire area if the area has 6/1 thunderstorm coverage.
DDo remember that vivid and frequent lightning indicates the probability of a severe thunderstorm.
DDo regard as extremely hazardous, any thunderstorm with tops 35,000 feet or higher, whether the top is visually sighted or determined by radar.
A28- 1146- 102- 00 | Federal Aviation Administration (FAA) Advisory Circulars |
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