well the new 747-400ER can carry up to 63,500 gallons. but you have to take into account the length of the flight... it burns 1 gallon of fuel a second, and about 5 gallons of fuel a mile. so in essence it wouldnt need even half a tank to get to its destination, when it could fly for 10 hours with alittle more than half a tank. Yeah it would have burned itself up, and everything else in the general vacinity, and it didnt. i found a video a while back about the crash on the pentagon, about what happened, and some witnesses who lived in the path that the 747 took. Im not gonna comment about it now but i'll find the video first.
If someone else knows where it is PLEASE POST.