A UFO in the radalt?
I'll apologise in advance for this post. It's the only place I can think of where I might get an intelligent answer...
I have a guilty pleasure in watching "The Curse of Skinwalker Ranch". For those fortunate people who are unfamiliar with this location/series the Utah ranch in question, formerly owned by Robert Bigelow, is the site of numerous unexplained events including UFO/UAP sightings. For some decades Bigelow and a US government entity were engaged in an investigation there, now taken over by another investor.
I'll spare you an account of the preceding events but a decision was made to use the owner's helicopter to conduct measurements of various parameters - unexpected EMF and gamma ray readings etc - at various altitudes above a target location where bizarre events, some measurable, like magnetic anomalies, had taken place. This involved flying a roughly circular, tight track at a set of target altitudes - say 5000 and 10,000 ft above sea level. The ranch is, as far as I recall (?), situated at about 4000 ft amsl. Initially at about 5000 ft the radalt started emitting a warning bleep and read in the range 45-55 ft agl. This was persistent but occasionally stopped (they didn't as far as I recall, show the indicated altitude coincident with the warning's cessation).
Attempting to proceed to the 10K level, where in previous experiments various anomalies had been witnessed, this alert became very persistent, sometimes reading as low as 35 ft agl. The pilot became unsettled by this as the warning persisted whilst maneuvering and so they aborted the tests. The radalt, according to the pilot, had never before exhibited this or any other anomalous effect. There was no information - in the series at least - about any follow-up tests to clarify the status of the instrument: which, unfortunately, is almost a defining characteristic of the series. Ground observers with binoculars were unable to see any other vehicle - drones etc - which might have triggered the warning.
So, to those who know, how would you rate this effect on the "strangeness" scale? Or put another way, can you think of any circumstances (other then the Sod's Law effect) which might contribute such a phenomenon?