PRIMUSr 880 Digital Weather Radar System
WEATHER DISPLAY CALIBRATION
Ground based radar observers of the National Weather Service (NWS) currently use video integrator processor (VIP) levels in reporting thunderstorm intensity levels. These radar echo intensity levels are on a scale of one to six. Refer to Section 6 of FAA Advisory Circular AC- 00- 24B for additional details.
To assist the pilot in categorizing storms in accordance with VIP levels, the indicator display colors represent calibrated rainfall rates in WX and preset calibrated gain. The relationship between the 4- color calibrations and the VIP levels is shown in table 5- 11.
As covered in the RCT description, intervening attenuating rainfall reduces the calibrated range and the radar can incorrectly depict the true cell intensity.
The radar calibration includes a nominal allowance for radome losses. Excessive losses in the radome seriously affect radar calibration. One possible means of verification is signal returns from known ground targets. It is recommended that you report evidence of weak returns to ensure that radome performance is maintained at a level that does not affect radar calibration.
To test for a performance loss, note the distance at which the aircraft’s base city, a mountain, or a shoreline can be painted from a given altitude. When flying in familiar surroundings, verify that landmarks can still be painted at the same distances.
Any loss in performance results in the system not painting the reference target at the normal range.
A28- 1146- 102- 00 | Radar Facts |
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