one thing to keep in mind is that this type of suicide bombing has never been done before. hijaking is/was fairly common. up until now, it meant just taking the plane to some location then bargaining. i think most people assumed that's what it was. so ... get along w/ the hijakers, they fly to timbuktu or wherever, and then we go home. i don't think anyone could've conceived of them crashing the planes into buildings.
also, the bbc reported that the terrorists began stabbing people to death in order to draw the captain out of the cockpit (and get themselves in). most of the flight attendants were dead or dying by the time the captain of the first plane came out (they have this on recording to control towers).
and the bbc also reported that the fourth plane was shot down by the usa. not been confirmed, but it's a very likely possibility.
i'm just glad i finally got a confirmation that my best friend (who's a united flight attendant) wasn't on board any of those flights. amen.