Radar Altimeters measure the plane’s altitude above ground level (AGL) directly by bouncing a radio wave off of the ground and measuring the time it takes and turning this time into a distance. They are normal on transports and unusual in small GA A/C. I feel they are underrated. Both King/Bendix and Collins make units for the GA market and both cost about $3k before installation.
Question: what are people’s experience with Radar Altimeters? Perhaps there’s some limitation I’m not familiar with that makes them so rare.
Question: where would one put the indicator on the SR22 panel? (it fits in a standard instrument hole) It seems like Cirrus thought they had given us everything they could ever want … but certainly they haven’t. It would be ideal to put the information from the RA on the big Arnav display, but that would require cooperation from Arnav.
I’ve thought about taking the analog signal from the RA unit and turning that into a synthesized voice which calls out altitude like a GPWS (Ground Proximity Warning System) in a transport A/C. But I’d prefer a canned solution. Also, is there some provision in the Garmin audio panel for audio annunciators? One could always use another speaker and just blast it out into the cabin loudly enough to get through the headsets. It would have a “quiet” button.
I know about EGPWS and the GA versions which use GPS, altitude, and a terrain database to give something which theoretically is even better than a radar altimeter. I’m all for this kind of thing. However, as far as I know, this is not available yet on the Arnav, the 430’s, or the Sandel EHSI. Also, I believe that the RA will be more accurate and is much simpler. And unless you’re flying in fast planes in steep terrain, EGPWS gives no more warning than good old RA/GPWS.
Thanks for any corrections, insights, suggestions, etc. you folks have.
For a little background on my personal interest in RA’s: my brother botched an instrument approach 20 years ago and got himself killed. Right solution: better training, but a RA would have saved his bacon. My approach: good training and avionics to back me up in case brain fade hits at the wrong time. Good training does not mean one never makes mistakes, etc.