3) Does this mean that the fortified-cockpit rules put in place after 9/11 are fundamentally flawed? Based on what we know now, I don’t think so. Here’s why:

After any disaster of this sort, it’s natural to think: Oh, if only we had Different Rule X, or Different Piece of Equipment Y, then none of this would have happened. And after the 9/11 attacks, that impulse led to the quite important step of fortifying cockpit doors. This was intended to ensure that no attacks like 9/11’s could ever happen again: Even if hijackers got weapons onto the plane, even if they surprised and overwhelmed the cabin crew, they wouldn’t be able to get to the controls and turn the plane into a flying bomb.

But there is an unavoidable dilemma with these cockpit doors. They have to be impregnable against normal threats. But there has to be some way to override them. Otherwise you could think of nightmare scenarios involving doors no one could unlock. For instance: a cabin fire or emergency decompression while one pilot and a flight attendant are inside the cockpit, behind a locked door. They pass out; meanwhile the other pilot, who had been in the bathroom, stands desperately outside the locked door, unable to get at the controls, put on an oxygen mask, and save the plane.