Wonder if they tested any old aircraft hangars down here in Florida for anthrax. Such hangars are easy to rent, easy to secure, and quite private. If these hijackers were doing anything on the side besides learning to fly, a hangar would be a logical, airy place in which to work- much more so than an apartment. Since they were in flight school, people would be familiar enough with them to not be concerned about them being up to no good in aircraft hangers.
I still find it interesting how the copycat kid pilot's handwriting on his suicide note was written at the same extreme angle as the hijacker's letters. Where is this kid's dad again?
Good questions.