The heavier parts would have been found inside the offices - even with such a disaster the military authorities are not about to let photographers loose, and any internally produced images would be delayed by security screening, hence the long delay before the security camera images were released. If the only attack that day had been on the pentagon, no doubt more pictures would have been released, but with the WTC devastation the Pentagon took a back seat. The fact that certain portions of the a/c survived hitting a bomb-proof concrete wall can be seen that a few pentagon staff members/contractors were listed as casualties twice- they had been passengers on the a/c so not only were they on the passenger list, but their ID's were recovered from the site, wrongly leading to the assumption that they were at work.