Jennings never said he heard the second plane hit. There is a reason for this: the time the second plane hit was just a second or two different from the time of the explosion Jennings and Hess experienced in the stairwell.
This is arrant nonsense.
You now have Jennings carrying out superhuman feats of speed.
You have him doing all of the following in ~15 minutes:
Receiving a telephone call some time AFTER the first plane crash (he doesn't ever say how long after, but it seems unlikely that he was on the "call first" list so it's a safe estimate that it was least a few minutes after and possibly 30 or more minutes after);
Making additional phone calls from wherever he was (he doesn't ever say where he was at the time);
Making arrangements to meet up with Mr. Hess (he doesn't ever say how long that took);
Meeting Mr. Hess (he doesn't ever say where he met Mr. Hess);
Making his way to 7WTC (he doesn't ever say how he got there or how long it took to do so);
Making his way into 7WTC and up to the 23rd floor (he doesn't ever say how long this took);
Finding that he couldn't get in to the 23rd floor (he doesn't ever explain why he couldn't get in or how long it took for him to determine that he was not going to be let in by someone else);
Returning to the elevator and back down to the lobby (he doesn't ever say how long this took, but assuming that the elevator he took up to 23 iniitally was still on 23 and had not gone elsewhere in the meantime, this could be as little as 3 minutes);
Locating assistance for an escort back to the 23rd floor (he doesn't ever say how long this took, but in the circumstances, it was probably several minutes at minimum);
Making his way back up to the 23rd floor with an escort who can let him in (another few minutes);
Wandering around the 23rd floor for a while (he doesn't ever say how long he was there after being let in on his second attempt);
Determining that the 23rd floor was empty (he doesn't ever say how long this took, but presumably he would have had to cover quite a bit of ground to make that determination);
Making several phone calls from the 23rd floor (he doesn't ever say how long this took);
Deciding to leave the 23rd floor;
Making his way back to the elevator from wherever he was on the 23rd floor (he doesn't ever say how long this took);
Determining that the elevators were out of service (he doesn't ever say how long he waited before giving up on the elevator);
Finding a stairwell (he says that Mr. Hess found a stairwell, so presumably that means that Mr. Hess went looking for one while Jennings continued to wait to see if an elevator would show up - probably a few minutes anyway); and
Walking down 15 stories - 30 flights - of stairs from 23 to 8 (this would have taken several minutes at minimum).
Sorry, but there is simply no way that Jennings' story jibes at all with having been able to do all of those things and cover all of that ground in ~15 minutes.
Heck, that's even more ambitious than Galileo's ridiculous and wholly unsupported claims. And that takes some doing.
From what I can gather, the OEM covered the entire 23rd floor. This is about the size of a football field without the endzones. So it's possible that Jennings, Hess, Nahmod, and Zarrillo were all on this floor at the same time, in two groups, and did not see each other.
Only if you concede that Jennings was not there at 9:03 a.m., and only if you concede that he was wrong about there being nobody on the 23rd floor, and only if you concede that he is mistaken in his time line - since it is quite impossible otherwise.
