AIRBORNE WX RADAR: WHAT'S WRONG
WITH THIS PICTURE?
Erik Eliel, the acknowledged expert on airborne weather radar use and training (www.rtiradar.com), has taught at the last three Twin Commander Universities. His radar training tips will appear periodically in Twin Commander Aircraft’s Flight Levels update and monthly eLetter.
2011 Twin Commander University attendee David Tenenbaum took this picture while flying in the mid-twenties on his return trip from the University in Southwest Florida. After just a couple sweeps, he immediately suspected a serious problem with his radar. Recalling that ground returns tend to be more reflective than weather, David noticed the absence of ground returns when he lowered the tilt (“D4.75°” or -4.75° in this image). Ordinarily, the display should have been flooded with ground returns. If it won’t display ground returns, it certainly won’t display weather.
For those of you who have attended my radar program at the University, you may recall an accident I discuss in which the post-accident investigation determined the radar in the subject aircraft suffered an 80 percent deterioration in performance, and the crew inadvertently flew into a thunderstorm—they simply did not see it on radar. Clearly there are some similarities between these two scenarios, except that David caught it early—on a clear weather day—and got it fixed before getting anywhere near convective weather.
You can see in the second image the “R/T FAULT” message that David saw during the radar’s self-test. Remember, the self-test function will not identify all faults/problems that may cause the radar to fail. The lack of ground returns was the key to identifying this major malfunction. Outstanding job, David.
He also asked me about the thin target (“radial”) at 1 o’clock and about 58 miles on the display. That is actually a great capability of his radar. I will address that, and more about what David discovered during his trouble-shooting process, in future pieces.
-Erik Eliel
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