Jack Bauer got in there and substituted a dud detonator for the real one. “It’s all part of the plan.”
Al Qaida has always had a Keystone Kops quality about it. 911 had more opportunities to fail than succeed. It only succeeded because of the incredible political correctness and incompetence of the FAA security apparatus, a tradition handed on down to the elephantine TSA.
It's catch as catch can, like the Apache who tried to lasso the Iron Horse. Silly Apache. Next time he tried loosening a rail.