9/11 Radar Tracking

Hey, fellow ATSers! I'm doing a little more research on the failed air defense of 9/11
Here's a link to what I've got so far -
they-let-it-happen.blogspot.com... fense-masterlist_30.html

I'd also like to toss out a few questions, in case anyone here can help me sort out a few details. My question is regarding radar tracking of the hijacked planes:
What I know:

There are two types of radar, primary and secondary, which should ideally both be used, layered together. As of 9/11, I think, this was the norm. Primary radar involves bouncing radar waves off the surface of planes - the returns are read on radar screens as little green blips. The advantage to primary radar, then, is that it never fails. It works by bouncing signals off an actual object, and does not rely on transponders. Just like every solid object casts a shadow, every solid object has a radar signature.Can give direction, speed, even atitude readings, but in crowded airspace, it is difficult to sort out which plane is which on a primary radar screen.

Secondary radar, also called “beacon-only radar,” is, it seems, not really radar at all??

Seems to be a transponder tracking system, akin to a wireless computer network. under normal circumstances, this is preferable. The signal of each plane tells a lot about it, with encoded information telling the carrier and flight number, altitude, and a four-digit hijacking code (this ‘silent alarm” was not used, to my knowledge, in any of the four flights on 9/11. odd.) But just as a computer in a network becomes invisible to the network if it is turned off, when the transponder on a plane is switched off, as all four were on 9/11 (one switched back on but on a different frequency and untracked), the plane becomes totally invisible to secondary radar.

Q: Any experts here? Do I have this about right?

A 2002 Aviation Week article said “ironically, FAA officials only a few months earlier had tried to dispense with “primary” radars altogether, opting to rely solely on transponder returns as a way to save money.” Had this FAA plan succeeded, it could have left flight trackers nationwide totally blind on September 11th, rather than half-blind, after the transponders were turned off. It’s strange that the FAA decided the money needed saved right at that time. But wisely, according to the article, “NORAD had emphatically rejected the proposal.” Thus NEADS technicians tracking the hijacked flights 11, 175, and 93 were only "half-blind” - the planes were visible on primary, but not secondary, radar.

Q: How is a transponder turned off? Is there a switch? If so why? Is it a crawl under and clip wires thing? Is it that easy? Should the hijackers have known how?

But as for the fourth plane, American 77’s approach to the Pentagon appears to have been a primary-radar-free zone. According to the Washington Post, the radar installation near Parkersburg, WV, which was tracking flight 77 'til it disappeared, “was built with only secondary radar - called 'beacon-only' radar. That left the controllers monitoring Flight 77 at the Indianapolis center blind when the hijackers apparently switched off the aircraft's transponder."

Q:Really? No radar track at all on an internal approach to the Capital from militia country? Left blind to non-compliant air violators? That doesn't sound quite right. Any good pointers on this anyone?

but my BIG Q I've always wondered: FTCs on 9/11, we've heard, had to visually try to separate the four hijacked jets out from more than 4,000 green radar blips representing aircraft in the nation’s airspace. Most were in the crowded but defenseless northeast sector, where the hijackings just blended right into the green swarm, and little could be read.

Was there not a technology in place to help them sort this out? One screen shows green blips - send it to a computer. One shows transponder tracks. Send it to the computer. Scan and compare the two. Green blips with no corresponding transponder are sorted out and sent to another screen of just a few blips. "That one's on course, try radio contact and keep an eye on him. This one's off course and no com, headed to DC - try contact again and get fighters out ahead of him..."

Does anybody know of a good link to reputable but not too technical resources on this kind of thing? Did they have such an ability? If not, then why not? Shouldn't they have?
Please understand I'm sometimes pretty smart and I've read a few things, but I'm not an aviation or radar specialist, so too much math or jargon goes over my head...

Absolutely bizarre synchronicity, swear to God, but two minutes after starting this thread I found this brand-new post on Cat Herder's 757 thred. Mouth! Let's talk!

Originally posted by Mouth
I haven't been on for a while, I've been in training for Air Traffic Control for quite some time. I havent read all of the recent posts in this thread, so I am not up to date, but I do want to bring some different light on this subject.

The reports indicate that the terrorists turned off the transponders on all the planes, which most people believe means that ATC could not be able to track them. This is incorrect.

Radar consists of 2 components: primary, and secondary. The systems ATC uses to track targets, ie, tag them with callsigns and verify altitudes, is connected to the secondary radar. The transponder sends signals that are interpreted by the interpretor (originao name) which then is decoded and the infromation is updated every sweep. when the transponder is turned off, secondary radar fails to work.

Now, Primary radar is different. It is like a ping system that is able to produce a blip on the scope, with no information on it.

There are very extensive procedures that are undertaken when a track is dropped and only primary radar is used. There are also many different ATC facilities that would have to have handled all the flights from the point that they lost comms, to the point of their crashings. You honestly think that all of these facilities, all the controllers, all the supervisors, would not speak up if they knew the official story was false? And, by official, I mean the general notion that flight 77 hit the pentagon.

Sorry, there is just too many people that would need to be involved for a conspiracy to happen, especially with so many random people involved.

[edit on 22-3-2007 by Caustic Logic]

I was discussing the whole 9/11 radar tracking issue with my colleagues, and what happened on 911 (apparently) is that the hijackers turned off their transponders, only allowing the conrollers to see the blip on the screen, with no altitude information, nothing at all, just the green blip. Now, a primary radar track can be easily dropped if the plane flies low enough, out of radar coverage. This is how the hijackers were able to fly freely.

A couple of things. First off, Airspace is divided amonst controllers, for example, one controller might own sfc - 14,000 ft, another from 15,000 to FL230, and so on up to FL600 (60,000 feet). Chances are either the controllers filter sets would filter out the clutter of non-adjacent sectors, so the text information in one sector would not be displayed in another. If you look at a radar scope, especially around busy airports, there are blips everywhere, but only the one with tags are the ones you are concerned with.

So, the hijackers turned off their transponder, which by the way has an on off switch which helps reset it when needed, flew low for a little bit to lose radar contact, and popped back up, without any controller batting an eye, especially in the northeast, where there is always a ton of traffic.

Now, the discussion whether there is or is not primary radar coverage around washington, I cannot answer that with total confidence, since I do not work traffic up there. However, it does not at all make sense to me that there would be no primary radar in washington DC, especially by the pentagon. I mean, there is an international airport right next to it, surely there would be some sort record of a primary target hitting the pentagon.

Originally posted by Mouth
I mean, there is an international airport right next to it, surely there would be some sort record of a primary target hitting the pentagon.

Actually, Reagan National Airport isn't an international airport. I know it's just semantics. Just making sure we get things correct. Thanks for your input here.

It's my understanding the wiring was central on at least one of the craft, where disabling the transponder would also disable the flight recorder.
I think they were on, no just wants to admit to it.

As to the no hijacking signal being sent, I believe there was a female FBI agent in contact with the airlines handling this. Poorly.

Something akin to: "Are you sure you're being hijacked...yes...no?"

Originally posted by Griff

Actually, Reagan National Airport isn't an international airport. I know it's just semantics. Just making sure we get things correct. Thanks for your input here.

Yes Thank you, like i said I an not too familiar with the airports in washington. There is also Andrews AFB within 10 miles of the pentagon, so it is hard for me to believe that neither airports, nor patomac (spelling) TRACON, or whatever center that has the overlaying airspace did not see or record the primary track of flight 77.

Flight 77 WAS tracked at the end of its flight. There were interviews with controllers that watched it heading in and make the final turn on their radar screens. That was one of the big arguments we had, because the controllers said "It made a fighter like turn. It's not something you normally see with a big plane because it's not safe." But all of the "It wasn't a 757" pages and people conveniently left off the second part of the quote and ran with the "It made a fighter like turn."

Bothered, there's no reason for them to have disabled the transponder. It has a switch marked "On/Off" right next to the dials to set the transponder code. And the transponder and CVR/FDR are on seperate wiring circuits and have NOTHING to do with each other at all.

[edit on 3/29/2007 by Zaphod58]

Originally posted by Zaphod58
But all of the "It wasn't a 757" pages and people conveniently left off the second part of the quote and ran with the "It made a fighter like turn."
[edit on 3/29/2007 by Zaphod58]

I beleive the quote was "evveryone in the tower thought it was a military plane" due to the speed and maneuvers it was making.

And they then went on to say that you don't see those maneuvers in big planes, because they're not safe to make. The clipped quote, which is the point being made is:

"The speed, the maneuverability, the way that he turned, we all thought in the radar room, all of us experienced air traffic controllers, that that was a military plane," says O'Brien. "You don't fly a 757 in that manner."

911review.org...

He went on to say in the full quote, after that, "That it's not safe." This is a perfect example of what I was talking about though. Clip the quote so it says what you want it to say, and not what he really said. Do you seriously think that a hijacker, knowing he's going to die, is going to care if he flies the plane in a safe manner?

Here's the completed quote:

"The speed, the maneuverability, the way that he turned, we all thought in the radar room, all of us experienced air traffic controllers, that that was a military plane," O'Brien said. "you don't fly a 757 in that manner. It's unsafe."

www.loosechangeguide.com...

ATC is used to planes being flown in the safest manner possible, and works to keep them safe, and get them safely to their destination. So when they see a plane being flown unsafe, and faster than commercial planes normally fly, then their first thought would probably be that it's military. Especially with them scrambling military fighters and trying to intercept the planes.

Originally posted by Zaphod58
Here's the completed quote:

"The speed, the maneuverability, the way that he turned, we all thought in the radar room, all of us experienced air traffic controllers, that that was a military plane," O'Brien said. "you don't fly a 757 in that manner. It's unsafe."

By the way O'Brian is a woman.

So answer the following question for me please.

1. What speed is the normal landing speed of a 757? What would happen if you were to lower the landing gear at the speed the 757 was flying when it hit the poles?

And that has WHAT to do with anything? The FDR and calculations done here show the plane was flying at 350+ mph which is a hell of a lot more than the landing speed of a 757. But what does the landing speed and what would happen have ANYTHING to do with what they saw on radar, or what hit the Pentagon.

Originally posted by Zaphod58
And that has WHAT to do with anything? The FDR and calculations done here show the plane was flying at 350+ mph which is a hell of a lot more than the landing speed of a 757. But what does the landing speed and what would happen have ANYTHING to do with what they saw on radar, or what hit the Pentagon.

Because of a military witness stating that the plane dropped its landing gear as it hit the poles.

So, the dozens of witnesses saying that it wasn't an American Airlines 757 aren't credible, were flat out wrong, or were forced to lie by the CIA/FBI/NSA/misc gov't agency, but the one military witness that saw the landing gear come down when it clipped poles is completely credible? You can't have it both ways.

And for the record, aircraft CAN extend their landing gear at high speeds, it's happened a couple of times that I can think of. If you're going as fast as Flight 77 was going, then it's going to suffer damage, and if it's down long enough you may even see it rip right off the plane, or at least part of it. But from the time he clipped the light poles to the time he hit the building the gear probably had barely started to move, IF HE EVEN TRIED TO EXTEND IT. It was a matter of a couple of seconds from the poles to the building. But it's interesting how only this one witness is credible to your eyes, and NO ONE ELSE reported seeing the gear come down.

Talking about a 757 making fighter like turns. I can tell you that I have witnessed such a thing first hand. It was a RNZAF 757 at last years Waddington show and it had the crowd, and me, gasping in astonishment at the way such a big aeroplane was being handled. So yes, it is completely possible. Try to get hold of the video footage if you can. its no Cobra, but its still not right to fly a transport like that. Those who say a 757 wont do this sort of thing are thus proven dead wrong.


*The RNZAF uses this aircraft purely for transport duties when not inducing asthma-like symptons in airshow crowds - it carries no pods, tanks or anything else scabbed on to the outside.

Originally posted by Zaphod58
So, the dozens of witnesses saying that it wasn't an American Airlines 757 aren't credible, were flat out wrong, or were forced to lie by the CIA/FBI/NSA/misc gov't agency, but the one military witness that saw the landing gear come down when it clipped poles is completely credible? You can't have it both ways.

Please show me where i said he was credible.

His statment was that a plane hit the poles and the pilot was loosing control, i assume the pilot thought by lowering the gear it would slow him and he couldd recover but lowering the gear just caused more probems.

I did not see you respond to the infomration on the RC-135s carrying pods.

ONE RC-135, the E carried them, and the NKC-135. I admit that I was wrong about those TWO particular planes. Happy? That doesn't mean that 757s and 767s do, can, or were carrying them at any point in time. Or that there are others that carry them.

Unusually for me this post is pure speculation ( ) but is it also possible that striking the poles caused some electrical or hydraulic damage and the U/C merely dropped of its own accord? In the confusion it is possible that only one gear leg came down rather than all three.

Originally posted by Zaphod58
ONE RC-135, the E carried them, and the NKC-135. I admit that I was wrong about those TWO particular planes.

Well thank you for admitting that, some people would not. I have been doing a lot of research and do research if anything is debated.

But we do not have the reports to say if a pod was found or not. And we do not have reports to state that a 757 or flight 77 hit the Pentagon.

[edit on 29-3-2007 by ULTIMA1]

At this juncture ultima1, may I ask why we are even debating about possible pods on these planes and what the relevance is. That basic point seems to have got lost among the squabbling.

Also, if not a 757, what else? The engine components are (I believe) fairly conclusively from an RB211 (I know you disagree). Apart from technical drawings sourced from Rolls Royce and Janes, they are also a match with the drawings in the Boeing spares and accessories catalogue (I never previously even knew there was such a thing). As only two types use the engine and it definitely wasn't a Tupolev for all sorts of obvious reasons I don't see a lot of wriggle room.

Weighed against this, in the interests of 'balance of probability', what actually says it wasn't a 757? The 'hole in the wall' stories have been pretty comprehensively rubbished many times over, so what is the evidence that another type of plane was present?

I dont think landing gear would make the plane more stable, but probably worse.


I would think that the pilot thought they could get a bounce or make a semi-landing into the pentagon because it was so low.