That the alleged 9/11 hijackers could so smoothly and successfully commandeer all four airliners;
Recall, if you will, that up to this time, aircrew were taught not to resist high-jackers. They were to cooperate to allow authorities to negotiate their release.
Exactly, first thing I said at the time.
Per passengers, it'd be easy enough for them to simply say that they were taking the plane to Cuba - which would not trigger a rush of self defense. Nothing to lose as a passenger if you know you've been drafted into a suicide mission.
Due to recordings, we know the cat got out of the bag on the PA flight. The others, no record that I know of.
IIRC-—THE HIGHJACKERS were found to have ‘taken flying lessons ‘ here in the USA, but never wanted to learn HOW TO LAND THE PLANE