"A former senior executive at the F.A.A., speaking to me on the condition that I not identify him by name, tried to explain. "Our whole procedures prior to 9/11 were that you turned everything [regarding a hijacking] over to the F.B.I.," he said, reiterating that hijackers had never actually flown airplanes; it was expected that they'd land and make demands. "There were absolutely no shootdown protocols at all. The F.A.A. had nothing to do with whether they were going to shoot anybody down. We had no protocols or rules of engagement.""