Let us try first to get something very important cleared, and mutually accepted.
The
time from O'Brien's identification of the plane tagged as LOOK as a B757, until impact; and subsequently the
speeds involved. And
we know quite well how both planes flew, in what pattern, when we just follow the officially given details, be it reluctantly given after FOIA
requests and a still pending court case.
That must be cleared, since I have the impression that the aeronautically schooled ones in this thread and in many others, strongly clench to a
totally impossible airspeed at different trajectories.
They seem not aware that f.ex. Sean Boger explicitly gave the number of seconds he estimated for the plane to cover the distance from coming in his
eyesight from over the Annex building, until impact.
Which does not fit at all the officially stated impact speed of 530 miles per hour.
We know that distance, and the seconds for both cases.
In both cases, the distance is a fixed known, but not the time and thus speed involved.
It turns out that my assumption that the two Farmer audio tapes (DCA and TYSON) started
after an introductory by a woman, of 46 and 14 seconds
respectively, was erroneous.
Both tapes start at the tape's beginning.
I found my posts back, on the TYSON timeline subject, in this thread,
"FAA or 84RADES data falsified, or both" :
www.abovetopsecret.com...
And found the official TYSON textual timeline back in this link :
aal77.com...
This above PDF-document's TYSON (Washington National tower) timeline gives a time of 13:36:29 = 09:36:29 EST, when ""GOFER06 advised it looked like
a B757."" That's the C-130 pilot O'Brien who said it.
The TYSON audio tape excerpt I made gave a (now revised 14 secs by me, see further on) timestamp of 09:37:14 EST.
Tape starts at 09:25:00 , and we hear O'Brien say "a 757" at 12:14 in the tape.
It also had an earlier entry,
09:33:45 Dulles Approach advised TYSON of a fast moving primary target currently
10 miles west of DCA (Reagan Tower).
And a few more entries, which give us an exact time frame to try to calculate an average speed.
"Try", since we have no exact straight line for that trajectory from 10, to 5 miles from DCA, to impact just north of DCA, but we can always assume
a straight line first and calculate average speed.
We have to check in the officially released last 757 trajectory, that huge circling around, how far a 10 mile and 5 mile line extends from DCA Reagan
International tower. And if part of the circle the 757 made is involved.
Then calculate again the 5 miles trajectory seen by O'Brien at the moment of plane-identification, as a bit longer partly curved trajectory, which
consists for a short distance, for that last 90° part of the 390° circle, as a thus minimal-partly curved trajectory, and then a nearly straight
line to impact :
09:36:16 GOFER06 issued traffic, eleven o'clock (a bit left of him), 5 miles(from DCA Reagan Airport) northbound, fast moving, type and altitude
unknown.
09:36:22 GOFER06 advises traffic in sight at twelve o'clock. (In front of him)
09:36:29 GOFER06 advised it looked like a B757.
09:36:51 GOFER06 states the traffic is still in a descent and rolling out northeast bound (at low altitude).
09:38:00 GOFER06 advised aircraft was down just northwest of DCA (Reagan Airport).
Thus we have 10 miles, if covered in a nearly straight line by a plane in 4:15 minutes = 255 seconds.
That's an average speed of 1 mile in 25.5 secs, which is 141 miles per hour.
Such a B757 would be falling out of the sky, if it flew so slow, I think.
Now let's assume a partly curved trajectory, as in reality this also occurred :
Then we assume 15 miles, covered in the same 255 seconds,
that's an average speed of 1.5 mile in 25.5 seconds,
which is 1 mile in 17 seconds, which is 211 miles per hour.
That is not even near the proposed 530 miles per hour all official sources posted here, as the end speed at impact.
Now let's be more precise, since we also fairly well know the time and distance covered for the 5 mile point.
O'Brien was moving to the west, while the B757 was moving to the north, when it crossed his path in front of him.
At 36:16 O'Brien reports it at 5 miles from DCA, but he is moving away from DCA himself, while the B757 is keeping the same distance to DCA until it
makes a slight turn northeast bound, and then flies in a nearly straight line towards the west wall of the Pentagon.
Thus, let us take the 09:36:51 time stamp as the B757 being still 5 miles from DCA Reagan Airport, then straight to the Pentagon where it crashed at
09:38:00.
That's 5 miles in 69 seconds, which is 1 mile in 13.8 seconds and that is an average speed of :
3600 secs (1 hr) divided by 13.8 secs x 1 mile is 265 miles per hour.
Which is still only half the proposed end speed of 530 miles per hour.
Someone will say that the plane only accelerated f.ex. during the last mile to reach that 530 miles per hour impact speed.
Then the plane needed how many seconds to cover that 1 mile?
Well, 3600 / 530 = 6.8 secs if it flew 530 miles/hr the full mile, which it of course did not, it build up speed.
But we still have a full 69 seconds time read out from the TYSON records for the last 5 miles, including that last mile. That means it had in that
case, 62.2 seconds to cover the first 4 miles, which lowers the already calculated average speed of 265 miles/hr over the full last 5 miles to 15.55
seconds per every 1 mile of that first 4 miles, which is 231 miles per hour.
So if it instantly accelerated in the last mile to those 530 miles/hr, then the average speed over the first 4 miles goes already considerably down.
But it needs much more seconds in reality to build up speed, so that would lower the first 4 miles average speed even more.
And the plane would have fallen from the sky again, before it could have ever accelerated.
He has a wonderful imagination, I have noticed so far, BTW. 
