Stories of a "2nd plane" shadowing it and flying away at the time of the explosion were floated in the media and reinforced with a few planted witnesses. We know for a fact there was no "shadowing" plane but we also know that a few dubious accounts and media reports quite explicitly floated this notion within the first days of the event.
This originally came mostly from a series of articles written by Terry Scanlon for the Daily Press about the C-130. If you read them it's clear that he deliberately has the plane in the airspace
at the same time as the explosion but of course we know from the Tribby video and the ANC witnesses that it wasn't there for about 3 minutes later.
Of course this is finally confirmed by the pilot Lt Col Steve O'Brien's statement that he was too far away when he first saw the explosion to even be able to tell if it was coming from the Pentagon!
The Pentagon is massive compared to a commercial airliner. Obviously he was too far away to see an impact or flyover but virtually ALL media reports erroneously either imply or flat out state that he did witness an impact. By the time he turned around to try and "follow it" it was too late.
But the 2nd plane cover story was very ambiguous at first and not limited to false reports of the C-130.
Indeed talk of any "mystery plane" at all in the skies would ambiguously serve as cover to anyone who saw the plane flying away.
That's why even talk of the E4B would be effective in this regard and now of course we know that proven dishonest conspiracy theorists like 911files blatantly used it for this very purpose only a few months ago in
Gaffney's book.