When I worked on the motorways in Cumbria it was always said by some of the more experienced comms engineers that when you were working on a signal transponder at 3am at the top of Shap the RAF would use your flashing orange beacons as a dummy target since they could be seen for miles in the dark. Never believed it until a Jag or Tornado (I couldn't tell which. It was dark. All I saw was two blue afterburners and deduced that it probably wasn't a Harrier) crept up one night and scared the poo out of me. Just how does something that noisy manage not to be heard until it's on top of you? The result was me sitting up suddenly, smashing the back of my skull on the door frame of the 600 cabinet and then swearing solidly for two minutes.
Attracted by the noise, no doubt, a couple of minutes after that a horse crept up behind me, put it's head over the fence and blew in my ear.
I shrieked like a girl and wished I'd brought fresh shreddies.
BTW, I've just thought about it and now I realise how a jet aircraft can sneak up on you at night. Obvious when you think about it . . .