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Letter from the author, 9/13/02

I've been contacted by Ed Haering, a researcher with NASA whose work with sonic booms is well-known (at least within those circles which concern themselves with such things). He was contacted by a reporter and asked to duplicate my process and give his opinion.

Put simply, he doesn't think the event was a sonic boom, and frankly, I'm inclined to agree with him. Below are salient excerpts from his email:

Dear Mr. Magley,

I was able to retrieve the SSPA data. Bottom line, I don't think what this seismograph measured on 9/11/2001 in Pennsylvania is a sonic boom.

First, for reference, see: http://www.galcit.caltech.edu/SonicBoom/f-18 especially the last plot. This is a known sonic boom, from a known aircraft, hitting a seismograph.

1) Notice that in all three directions, U(p), N(orth), and E(ast), the first downward peak happens simultaneously. It also shows the ground initially moving down, south, and east, which is consistent with the direction of the sonic boom from the F-18.

2) The time difference between the first downward peak and the first maximum peak is on the order of 0.15 seconds. This is consistent with the first plot of the website above showing 0.13 seconds for a pressure measurement of the sonic boom. The pressure plot is the same shape as the initial part of the seismograph displacement plot, just flipped vertically.

3) Prior to the sonic boom, the seismograph data is very flat, and there is oscillations after the boom that dampen out in a few seconds.

Now referring to the SSPA data, I looked at the three axes of displacement of the earth. Plots are attached to this email.

1) In the closeup plot, sspa20sec.gif, the event does not happen simultaneously in all three axes. The Z axis on the bottom plot has the event occuring a full second after the north and east axes events, which is an eternity as far as a sonic boom is concerned.

2) The duration of the event is much greater than one would expect of a sonic boom. The shape of the event is not consistent with the "N" shape of a sonic boom.

3) In the plot sspa2min.gif, there is a considerable amount of oscillations before the event in question.

I don't know what caused these wiggles, but it doesn't look like a sonic boom to me.

Sincerely,

Ed Haering

P.S. You can trust me, I'm with the Government, and I'm here to help! :-)

31,000 -odd people later....

I've always said that if I were shown to be off track on this, I'd be here on the site letting people know. So, to my thinking, I've been off-track. There are others looking at the data as well, and perhaps they'll have some good idea what the event was, on that singular day, at that singular time, and in that singular place in the country.

Amazing coincidence? It appears so. I plan to leave the article up for a week or so, with the note at the top pointing people here. Then I'll scoot the article onto a back page, put another note where the home page goes, and call the thing done -- unless someone with Mr. Haering's credentials tells me he's the one that goofed. Which I'm not expecting.

What caused the event -- still a mystery, sure. But it looks like it's not what I (and some others) thought it was. Am I disappointed? Far from it; I'm thrilled to have corresponded with the interesting people that have taken the time to write. I'm not convinced this completely exonerates our good Air Force from any involvement in Flight 93's demise, but I'm pretty sure I've got nothing here that will turn the debate one way or another.

I'll be keeping up with ongoing investigations at Flight93Crash.com, and the discussion board attached to it. There are still stories to tell, and some pretty remarkable people to tell them.

But I don't think they have to do with seismic monitoring stations detecting aircraft....

At least, not military aircraft... (was that some foreshadowing, or what?)

Thanks again to everyone, and take care of each other.

Robb

 

previous updates: 9/05/02, 8/15/02