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UAL93 Encounter With PIT

BCR

Master Poster
BCR
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I thought some of you might find this screen capture of PIT's local radar (ASR-9) interesting. It runs from 1345 - 1358 UTC. UAL93 is tagged N123 prior to encounter and then proceeds on as an untagged primary target.



Of course it is untagged after the encounter because it was the FAA's finest hour. The air traffic controllers ran for the hills and nobody was left in the tower to re-tag it.

YouTube quality really stinks, so here is a GIF version that might be a little better.

PIT GIF

Here is the audio for the PIT Arrival North position from 1339 - 1403 (UTC).

PIT Arrival North
 
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If I'm to understand correctly, the Green lines are flight planned aircraft with specific squawk codes, the purple are 1200 squawk G.A aircraft, the red is primary radar?
 
Your guess is as good as mine on that one. I think you have it right, except that the green are targets that have been tagged with identifiers, either by the transponder or ATC. The N123 for UAL93 was added by ATC since at that time it was a primary target.
 
Oh right, if it's primary track was tagged, why did it un-tag and continue as an unknown target? Did it drop off the primary radar for a few seconds and cause it's target to un-tag itself?
 
cjnewson88 said:
Oh right, if it's primary track was tagged, why did it un-tag and continue as an unknown target? Did it drop off the primary radar for a few seconds and cause it's target to un-tag itself?
Click to expand...

It went over the "top" of the ASR-9, so it was not tracked for a short time. When it re-emerged, there was no ATC to tag it again. They were running for the hills :D

PIT Arrival North audio
 
Of course we are laughing about this now, but at the time (1355) there was a commercial aircraft, CHQ4334 (Chautauqua Airlines) on approach and descending. Crossing it's flight path was another plane, N8222N holding at 9,000 feet. Looks like they had to take some serious evasive action (although they were still a few thousand feet apart in altitude).

Was not a smart move leaving hundreds of lives hanging in the balance like that.
 
BCR said:
I thought some of you might find this screen capture of PIT's local radar (ASR-9) interesting. It runs from 1345 - 1358 UTC. UAL93 is tagged N123 prior to encounter and then proceeds on as an untagged primary target.



Of course it is untagged after the encounter because it was the FAA's finest hour. The air traffic controllers ran for the hills and nobody was left in the tower to re-tag it.

YouTube quality really stinks, so here is a GIF version that might be a little better.

PIT GIF

Here is the audio for the PIT Arrival North position from 1339 - 1403 (UTC).

PIT Arrival North
Click to expand...

I know nothing about flying, but isn't it "PGH", not "PIT"?
 
Are you saying there was a Pittsburgh stand-down??!?!!!?!?!?

This could unravel the whole plot! Where did those orders come from? Allentown, Hershey, or Scranton could be implicated. The trail might even lead all the way back to Harrisburg!
 
EventHorizon said:
It's PIT.

http://en.wikipedia.org/wiki/Pittsburgh_International_Airport
Click to expand...

Well, pardon me! I lived there for eight years, and I'm sure I knew the call letters at that time (since I flew in and out regularly), but obviously I've misremembered.

I wonder where I got the silly idea it's PGH. Just confusing the common abbreviation for the city with the airport, I guess.

Thanks for the correction. Though, frankly, I'd rather it hadn't come from a Rangers fan. Bah.
 
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phiwum said:
Well, pardon me! I lived there for eight years, and I'm sure I knew the call letters at that time (since I flew in and out regularly), but obviously I've misremembered.

I wonder where I got the silly idea it's PGH. Just confusing the common abbreviation for the city with the airport, I guess.

Thanks for the correction. Though, frankly, I'd rather it hadn't come from a Rangers fan. Bah.
Click to expand...

Harrisburg used to be HIA, but it changed to MDT (Middletown) sometime since 1985. Maybe there was a general update. The airport is in the same place. Only the call letters changed.

Either that, or I misremembered as well. ;)
 
cjnewson88 said:
They evacuated?? That's embarrassing...
Click to expand...
A lot of ATC facilities evidently evacuated that day, we did at Boston Center when we were advised that a B757 was going to crash into Boston Center and that it was imminent. We did get everybody on the ground first and then we evacuated. The call of the imminent aircraft was a miscalcualtion of our Regional Office of a Coast Guard aircraft that we had identified 20 minutes earlier. But who knew that day, if you were told to go you went. We considered ourselves under attack.

Notice the call sign they tagged, pretty common to tag an unknown as N123.
 
I was hoping you would check in Cheap Shot. I would hate to be beating up on the guys at PIT without anyone giving a defense. But face it, there is something of a difference here. In this case, they were the only one's who were able to track it and the other local traffic. I would have expected at least one controller to rise to the occasion.
 
phiwum said:
Well, pardon me! I lived there for eight years, and I'm sure I knew the call letters at that time (since I flew in and out regularly), but obviously I've misremembered.

I wonder where I got the silly idea it's PGH. Just confusing the common abbreviation for the city with the airport, I guess.

Thanks for the correction. Though, frankly, I'd rather it hadn't come from a Rangers fan. Bah.
Click to expand...

That was my flight sim geekiness coming out.
 
BCR said:
I was hoping you would check in Cheap Shot. I would hate to be beating up on the guys at PIT without anyone giving a defense. But face it, there is something of a difference here. In this case, they were the only one's who were able to track it and the other local traffic. I would have expected at least one controller to rise to the occasion.
Click to expand...
They may have been evacuating for N123 (UAL93). Don't know. But since it was hijacked and not under ATC control they may have assumed it was aiming for them. Though I can't imagine leaving any kind of ATC work that needed to be done first, you should clean up your mess before you go.
 
Looks like I'm going to have to do a full radar analysis for UAL93 similar to what I did for AAL77. I have discarded any idea of doing such a thing because of the enormity of the task. So many different data sets, all in a different and unfriendly format. However, the learning curve will not be quite as steep as it was before, so perhaps it won't take as long.

Due to the release of Gaffney's new book, Black 9/11 and the suggestion that a UAV "shot down" UAL93, I did some rough analysis on some ZDC data to get a lower altitude look at the moments just after the PIT screen capture in the OP. And sure enough I found something that is sure to be exploited and misinterpreted.

bogies.jpg


During the minute of 1401 (UTC), two slow moving targets are seen in very close proximity of UAL93. Here is a slightly better graphic of the target tracks discovered in this particular data set.

ual93_targets.jpg


Needless to say, targets #2 and #3 are of particular interest. Target #2 makes a "direct" line to the abandoned (in 1999) airstrip at Indian Lake. Here is a very rough animated GIF which includes the ground clutter returns also.

zdc_ual932.gif


Of course I forwarded my worksheets and data set to the 'radar team' and we've spent the last few days scratching our heads. But, here are our very preliminary findings and thoughts.

1) Both targets exhibit speeds of 50-70 knots. A little slow for even small planes and definitely not likely candidates for a UAV such as the Predator (stall speed ~54 knots).

2) No meteorological phenomenon known to exist that day which could account for them.

3) Too far from the radar facilities (>50 nmi) for birds.

4) Not enough data to make an identification.

So, because of 4), here I go again. I reckon this thread will do just as good as any for updates.

And how could I have forgotten? Here is a link to the GE kmz. I should also mention that this is primary-only data.
 
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By the way folks, there is a question on the table that some of you might be able to assist with. What were the meteorological conditions on the surface and at altitude in the Shanksville or Pittsburgh area on 9/11 at the time of the crash? Factors such as wind speed and direction could be a factor in these low speeds.
 
Try overlaying the radar tracks with an aviation sectional or a good map of the area and see if a highway or railroad matches them. I've had ATC call out primary targets caused by ground vehicles; Cedar Rapids approach, for example, once had me looking for a couple of slow moving primary targets, but the controller said it was most likely trucks on I-80. Unlikely, given the distance in this case, but maybe the sharp edges of a truck or rail cars acted as corner reflectors.

It's also possible that the targets were a couple of planes without electrical systems; a Cub bucking a 20 knot headwind would match the speed profile.

ETA: BCR, I just saw that you considered that last item - I hadn't scrolled that far on my iPad.
 
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