A friend of mine mentioned this one to me today. If the pilot had the option to gas the interior of the plane and put everybody to sleep, if there was a problem in the cabin. Naturally he and the copilot could put on a mask first, then when the passenger and crew are safely asleep, they could go back and check on the problem or immobilize any threat.

This would not work too often after the first time, because the terrorists would start figuring out a way to avoid the gas, such as the oxygen masks above every seat. I have a hard time believing they could get gas masks through customs without raising suspicians.

-Steve G.