I usually have ADSB on my laptop/phone and either take an occasional glance when using either or if I hear something. I was in a meeting in Farringdon a dozen plus years ago; distinctly heard the sound of radials overhead, would love to have had/known about ADSB back then. Air Atlantique were still flying their DC-6s at that point.
I understand the AN-22 was indeed destroyed... It was a very distinctive sound which I heard three times, once distantly from Frimley as the famous Farnborough visitor departed, twice overhead here. First time it was leaving a vapour trail and I was looking for something much lower, so loud was it. Bins revealed what was leaving the trail...
Heard the weirdest jet noise while walking through some woods at Selsdon yesterday - could hear a Spit getting airborne from Biggin and the strange sound seemed to be above me, quite deep with hints of blue note... Nothing on ADSB, crimminy... Looking up through the lattice of I suddenly realised I was directly under 400kv powerlines and the sound was the quite strong wind blowing through them! I knew the line passed through the area, just never noticed the cables crossed that stretch of woodland! In my defence, most of the year the trees are well canopied and I normally look down more as that section of path is well mined by badgers and there are poodle bombs to avoid as well. One of the pylons is just the other side of the woods it seems, also screened by the trees.