A UFO in the radalt?
Joined: Jan 2011
Posts: 776
Likes: 84
From: Seattle
It's a distinct possibility. RAs use a system of frequency modulated continuous wave radar. A CW signal is ramped up in frequency and the reflected return signal differs in frequency based upon the travel time. So the system isn't range gated, where subsequent pulses can be spread out to avoid such misinterpretation. The failure modes would be something that a radar expert (which I am not) could expand upon.
Joined: Jul 2011
Posts: 187
Likes: 37
From: N/A
Radalt is a tranceiver there can be an emitter in the vicinity which “fools” your radalt. I heard even 5G cellphone communications might cause these kind of issues!
https://tc.canada.ca/en/aviation/ref...asa-no-2021-08
Joined: Feb 2005
Posts: 673
Likes: 1
From: On the green bit near the blue wobbly stuff
I dont think I have seen a helicopter radalt thats works above 2000' AGL. I am guessing because they are subject to error above this sort of value. Radalt unreliability is not uncommon for all sorts of reasons - eg it doesnt like wavy long grass. UFOs are likely to be rather a long way down the list.
Joined: Apr 2010
Posts: 850
Likes: 0
From: USA
Assuming the original poster is at all serious, this brings to mind a saying common in the medical profession: "When you hear hoofbeats think horses not zebras."
As the OP has hopefully learned from this thread, there are an awful lot of common reasons ("horses") for radar altimeters to read spuriously or erroneously, all of them clearly explainable by the laws of physics, and such events occur often enough, at all altitudes, to make extraterrestrial causes ("zebras") extremely unlikely.
At the risk of writing the glaringly obvious, it should also go without saying that "reality" TV producers and directors are exceeding good at, and quite in the habit of, making mountains out of molehills.
As the OP has hopefully learned from this thread, there are an awful lot of common reasons ("horses") for radar altimeters to read spuriously or erroneously, all of them clearly explainable by the laws of physics, and such events occur often enough, at all altitudes, to make extraterrestrial causes ("zebras") extremely unlikely.
At the risk of writing the glaringly obvious, it should also go without saying that "reality" TV producers and directors are exceeding good at, and quite in the habit of, making mountains out of molehills.
Joined: Dec 2005
Posts: 1,581
Likes: 73
From: England
Originally Posted by [email protected]
Hmm, tricky decision when the rad alt starts to misbehave - do you :
A. Check the connections, the T/R and the aerial or
B. Assume it is alien interference.................
A. Check the connections, the T/R and the aerial or
B. Assume it is alien interference.................
Ask an avionics engineer. He will confirm alien interference as there is nothing wrong with the equipment.
Joined: Aug 2009
Posts: 24
Likes: 0
From: Nova Scotia Canada
There is nothing wrong with equipment and it definitely is NOT alien interference.
Most Radio Altimeters are design limited for height range. Most will flag and remove the height indication when beyond design limits, but not all. Some use different FMCW processing techniques to provide limited “look ahead” features.
Some Radio Altimeters designed for special applications such as guided weapons and military aircraft use PCM instead of FMCW. These can also have different range design features. These are by definition much more expensive and PCM altimeters are not common in civil aircraft although I have seen them installed for special operational applications.
Many are unreliable overwater particularly if the surface is flat calm, the same can happen over reflective sand based terrain. Antenna position and in particular antenna spacing and surface induced discontinuities are optimised for individual aircraft and are or should be in compliance with the equipment manufacturer installation specifications. There should be FM Supplements and or operating instructions for individual aircraft.
Sincerely, Avionics Design and Systems Integration Engineer.
Most Radio Altimeters are design limited for height range. Most will flag and remove the height indication when beyond design limits, but not all. Some use different FMCW processing techniques to provide limited “look ahead” features.
Some Radio Altimeters designed for special applications such as guided weapons and military aircraft use PCM instead of FMCW. These can also have different range design features. These are by definition much more expensive and PCM altimeters are not common in civil aircraft although I have seen them installed for special operational applications.
Many are unreliable overwater particularly if the surface is flat calm, the same can happen over reflective sand based terrain. Antenna position and in particular antenna spacing and surface induced discontinuities are optimised for individual aircraft and are or should be in compliance with the equipment manufacturer installation specifications. There should be FM Supplements and or operating instructions for individual aircraft.
Sincerely, Avionics Design and Systems Integration Engineer.
Joined: Dec 2014
Posts: 550
Likes: 12
From: Africa
FAA Warns Of 5G Effects On Radio Altimeters
😂😂😂👍
Radalt is a tranceiver there can be an emitter in the vicinity which “fools” your radalt. I heard even 5G cellphone communications might cause these kind of issues!
https://tc.canada.ca/en/aviation/ref...asa-no-2021-08
Radalt is a tranceiver there can be an emitter in the vicinity which “fools” your radalt. I heard even 5G cellphone communications might cause these kind of issues!
https://tc.canada.ca/en/aviation/ref...asa-no-2021-08
The FAA has issued a Special Airworthiness Information Bulletin (SAIB) alerting aviation manufacturers, operators and pilots to the potential adverse effects of new 5G wireless networks on radio altimeters. Released on Nov. 2, the bulletin—AIR-21-18—recommends that aircraft and avionics...
