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"A radio altimeter measures a plane’s height above terrain by bouncing a radio signal off of the ground and recording the response time." If that's the case, h
by fipar 7y ago
"A radio altimeter measures a plane’s height above terrain by bouncing a radio signal off of the ground and recording the response time."
If that's the case, how come a negative reading was not assumed as a malfunction? Am I missing something, or can a plane ever be in negative altitude with respect to whatever this radio signal is bouncing off from?
edit: s/never/ever/
- nradov 7y agoRadio altimeters always have some margin of error, so a slightly negative altitude reading doesn't necessarily mean it's malfunctioning. A better approach would probably be to cross check the radio altimeter with the GNSS receiver and navigation system, then alert the pilots in case of a sustained large discrepancy. Of course that would further complicate the avionics and risk introducing additional failure modes.
- fipar 7y agoThanks!