The fact is there were many, many witnesses. I heard a 911 call from an off-duty pilot who identified (correctly), the plane as it passed by his window, and he could see the result of the crash seconds later. Now, he didn\'t see the crash, but assuming you\'re right, where the heck does the enormous plane go, so that it dissapears (with all the people on board), and a truck explodes?
Right. Other witnesses, and the videotape, say/show the plane stuck the GROUND in front of the pentagon, and at those speeds, and with thousands of pounds of kerosene on board, there isn\'t going to be much left of the plane. This wasn\'t an attempted crash landing/ditching at 150 mph (those planes CAN fly a lot slower than they do when they land, you know), this was a smash landing at six or seven hundred mph. The plane is obliterated, initialy by it\'s impact with the ground, then by it\'s own fuel which burned for quite a while.
I would chalk up the lack of MORE serious damage to the pentagon as simply this. It\'s a very old military building. In the past, construction used more steel, more concrete, and thicker everything, and even so, the plane did a lot of damage, mostly from it\'s kerosene, rather than it\'s initial impact. Had it struck the building itself, I\'m sure the damage would have been 20x worse.