I'd expect the definition of a powered aircraft to include the ability to maintain some given flight altitude and speed for some appreciable amount of time. It

I'd expect the definition of a powered aircraft to include the ability to maintain some given flight altitude and speed for some appreciable amount of time. It is possible to do something sort of like this in a space capsule returning to Earth, where you muck up your entry vector and come in at too shallow an angle. You can then (depending on the circumstances) bounce off the atmosphere, and gain altitude briefly. And then you probably come back in the atmosphere on too steep an angle, and die due to g-load or overheating.