Here's some loose threads on Flight 93; there are some who claim a real flight was shot down away from the "crash site".

[link to www.youtube.com]

(CBS interviews some pilots who say they were on the air and were told to shoot it down but didn't know it)

As to "the passengers" took it down themselves, that's a whole other issue that's nonsense, and false heroics. But anyway, another Military unit seems to have actually ended up shooting it down -- with some people on it -- maybe. But there's suspicion about that, too. Shanksville didn't crash at the site -- whatever else was going on.