The academy's powered flight, glider and parachuting operations have been called off since Saturday so that the U.S. Forest Service could use runways for helicopters used to fight fires along Colorado's Front Range, Van Winkle said.

CNN: Crews go on offensive against growing Colorado wildfire

Boeing has also flown a Dimona motor glider with an electric motor powered by a fuel cell.

ECONOMIST: Electric planes

Within a few moments, a passenger jet powered by four Rolls Royce engines had become a glider.

BBC: When volcanic ash stopped a Jumbo at 37,000ft