“Everybody has a plan until they get punched in the face.”
-Mike Tyson

I think you're training should simulate getting punched in the face because a situation like 9/11 is no doubt worse than that. If you're like me, participating in a competition under pressure would be a lot more productive than reading about how to deal with a 9/11 situation or whatever. I personally learn best from doing something.

I can't do 9/11. So, a substitute is playing organized sports, especially games or competitions. They greatly help you get a grip on where you stand with controlling yourself during a chaotic/pressurized situation. The higher the stakes, the better the training will be. Instead of studying how to deal with anxiety, you're actually dealing with it on a regular basis. You must learn how to deal with limited information in a short amount of time, and you must learn how to be calm enough to do things correctly right now, not during the post-game analysis when it's too late. For us older folks, we can participate in races and go for a personal best. For the younger folks, you have more options, like playing school sports, taking the last shot, etc.

I imagine guys like Brett Favre and Michael Jordan would do quite well in a chaotic situation like 9/11, if they had to do so.