After 9/11 they started using armed air marshals on flights, or so I heard at the time. The problem is if Muslims (or old ladies in wheel chairs, since I don’t want to profile) were doing as much planning as they did in the first attack, couldn’t they kill the armed marshal as the first order of business and get his gun? Even though they were pretending to be passengers, it might not have been hard to notice that they never got off the plane. On the other hand, the terrorists had to physically break down the doors to the cockpits, giving the pilots plenty of time to prepare.
Yes, I know about the marshals, but as I understood it, they were not on every flight. And I hear your argument about the pre planning, and I would say two things to that:
A: nothing is perfect, including this idea, but it’s a damned sight better than what we have now and
B: we were caught with our guard down on 9-11 - that would not be the case afterwards. I think you’re letting the perfect be the enemy of the much better….