Glueball
Wasn't the purpose of taking the planes on 9/11 to turn them into air to ground missiles. If they blow up a plane on the runway with a cement truck, its just another aviation accident. (don't read that the wrong way). A plane in the air under the control of a terrorist is a missile of serious proportions. I don't like TSA's handling of the first training class, but I can't imagine a plane under terrorist control getting down safely. It will either become said missile or the target of a F-18 sidewinder missile (or something). What do they have to lose by having a gun onboard?