NORAD is a missile defense system. With the end of the cold war, it's pretty inoperative. On response to the hijackers, go home and slice your throat open with a box cutter. For people who are well-trained and have anticipated the moment of truth (their own sacrifices) for the better part of their lives, it wouldn't be so hard. Especially in a panic situation. The hijackers also broadcast a message accidently to air traffic controllers. Look it up.