My thesis is that UFOnauts are people like us. So they have habits and weaknesses like everybody else. So, when (they think that) nobody is watching them they just go silly and have some fun. For some reason, it seems that they find quite funny to follow large planes and spook passengers. There is that classic video where a drone UFO flies around Concord that was on a flight to prepare British Airways advertisement. Second such opportunity is now classic video by Crow 777 on YT, where UFO shoots a beam of light while flying through contrail. On another forum there was a lady who watched UFO fly for a short time along the tip of the airliner she was on. It would be quite funny if 100s of similar videos turn up on YouTube and force governments to provide explanation. Whatever the reason, UFOs like to fool around with contrails and airliners. Up at 30,000ft UFOnauts feel quite safe, because they are not visible by naked eye from Earth and there is no foot traffic to stumble upon them by accident. If any military plane tries to intercept, they can easily spot it from miles away. Most likely their mother-ship can't see them either, although that's a wild one ;-). If we all build monitoring stations like the one that I described above, we can together monitor a huge patch of the planet's sky. And some brave, technically savvy, soul can attach such AI camera to an actuated telescope and go far beyond modest 50mm focal length that eBay offers. Telescope without glass lenses, just with mirrors, like Newtonian design, would work quite well even with FLIR sensors, that can't see through glass.