Barely take off? Taking off a plane is fairly easy, it's landing that's hard. They didn't need to learn the landing part. Further, they didn't launch the plane, they crashed it. People have insurance policies, it's a prudent thing to do. They were doing drillls... Because there was a known threat. I'm not saying that that's not a cool story, but occam's razor says that my theory wins since it doesn't involve thousands of people coordinating and not one person spilling the beans. Then you've got the fact that, well over a billion muslims want to blow up the US, and were happy.