[ventus45]

HDTBill, the idea of a flame-out producing a signature, detectable from space, never entered my head before. On thinking about it, I would not think it likely for a number of reasons. First, the shutdown procedure for a jet engine is simply to turn the fuel valve off. No fuel in the combustion chamber equals flame-out inside the combustion chamber. I can't see any fuel being un-burnt in the chamber, then making it's way past the turbine disks and out the exhausts and then igniting. Second, the engine exhaust is under the wing. Even if there was a little "flame torch" it would have to be long enough to stretch behind the flaperon to be seen from above. In any case, even if there was some sort of "flame-out", it would be small and short lived and of very low "energy" that I doubt any satellite would detect, day or night.