Timeline for How do radio altimeter systems compensate for objects on the ground?
Current License: CC BY-SA 3.0
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| Jan 6, 2018 at 20:30 | history | edited | kevin | CC BY-SA 3.0 |
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| Jan 5, 2018 at 9:06 | comment | added | Chris H | @abelenky because a (simple) detector circuit will detect a rise, there can also be a bias towards higher objects as they reflect first. This can to some extent be tuned out so a single prominent object doesn't cause too much trouble, but of course we might want to know about prominent objects | |
| Jan 4, 2018 at 21:57 | comment | added | Mark | @abelenky, the radar performs a weighted average. A strong reflector like the metal body of a truck will count for far more than a weak reflector such as a tree. | |
| Jan 4, 2018 at 21:03 | comment | added | Terry | I can believe that these days with better equipment and with pilots doing less hand flying than in my time, the answer is descriptive of current practice. However, in flying 747s at 2 carriers during the 1990s, that's not quite how we did it. Once in sight of the runway and below 1000 ft on the baro altimeter, we didn't use it as there was no need with the exception that the baro altimeter was used to call decision height when on an ILS. The first call of our old radio altimeters was 100 ft, although many of them weren't "talkers" in which case the f.e. made the call. | |
| Jan 4, 2018 at 20:00 | comment | added | abelenky | Also, a radar beam is not a laser; it will not measure a single spot: rather the signal will hit a section of the ground (the higher the transmitter, the larger the area it will hit), and the reflection will effectively be an average over that area. Unless a truck or tree is absolutely massive, it will get averaged with the surrounding area and distort the readings a negligible amount. | |
| Jan 4, 2018 at 17:35 | history | edited | kevin | CC BY-SA 3.0 |
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| Jan 4, 2018 at 16:36 | history | edited | kevin | CC BY-SA 3.0 |
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| Jan 4, 2018 at 16:26 | history | answered | kevin | CC BY-SA 3.0 |