They believe the plane impacted but it was concealed by the fireball.
So as I understand it they stated that they didn't see the actual impact, since it was concealed by the fireball. To me that rises a few questions:
1. The fireball lasted what, some 8-9 seconds? Was that enough time to conceal a plane flying over the Pentagon and away? (Eg, it could have concealed the impact, but not last enough to account for a flyover. As I see it it would have to conceal not only the plane flying clear of the building, but at least a few seconds afterwards. I imagine any sane pilot would like to get some altitude after such a manoever.)
2. But... how did the fireball come
between the witnesses and the airplane? If an explosion would be timed to occur to conceal a plane doing a flyover, it couldnt be set off before the plane passed, since that would give the witnesses a simultaneous look at plane and fireball - and it would risk the plane to be damaged by the explosion. If, on the other hand, the fireball were to come between the witness and the plane clearing the roof of the Pentagon, it would have had to go off after the plane had cleared the building, making the timing to make the illusion real, extremely difficult to achieve. And again dangerous for the plane in question. And we are still talking about a Boeing, right? I imagine the plane had to start gaining altitude to clear the building before the explosion went off, and that again would let the witnesses understand that the plane was flying over. Did any witness state that they saw the plane ascend just prior to the explosion?
3. And even if the timing could be made so that witnesses would be fooled, it would only do so from one angle. The airplane would be visibile from three other sides. Are there any witnesses seeing a Boeing (or any other plane) flying clear over the Pentagon?
4. I would imagine that at that speed the distinction between "hit" and "fireball" is somewhat blurred, almost making the "fireball" the "hit". When the witnesses say they couldn't see the impact because of the fireball, is that distinction really not moot? The fireball is the impact. You wouldnt expect to see a perfectly good plane, fully tanked, just enter the building nice and slow, only to be followed by a fireball. Remember, the plane flew fast.
/S