Flight 77 Animation
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Just to add a little to what DR said... I Google Earthed the area in question and the elevation is 37 feet around where the poles were knocked down. If those things are 30 feet tall, we have a 757 at 65' pressure altitude.
But, as DR said, error is easy to come by when dealing with baro altitude data. When flights reach 18,000', the pilots dial the baro setting on the altimeter at 29.92. Is it possible to get the ATIS info from DCA that morning DR? Someone has to have it. In fact, ATC recordings from Dulles should give altimeter info on clearance right? Dulles is only 20 miles away, that should be close enough for us to be able to deduce what the altimeter indicated at the time of impact..
Also, radar altimeter data is input to the FDR under 2500' at a sample rate of 1.2 Khz. If we had access to the radalt plot we could deduce how high the 757 was because we know the speed of the aircraft in feet per second(780), the distance from the first and last poles to the impact point(559' and 1064'), and time it would take using the speed against these two distances(0.72 and 1.36 seconds).....The FDR sample rate is still fine enough to be able to get an exact altitude if we had the data. Maybe Mike needs another FOIA request?
But, as DR said, error is easy to come by when dealing with baro altitude data. When flights reach 18,000', the pilots dial the baro setting on the altimeter at 29.92. Is it possible to get the ATIS info from DCA that morning DR? Someone has to have it. In fact, ATC recordings from Dulles should give altimeter info on clearance right? Dulles is only 20 miles away, that should be close enough for us to be able to deduce what the altimeter indicated at the time of impact..
Also, radar altimeter data is input to the FDR under 2500' at a sample rate of 1.2 Khz. If we had access to the radalt plot we could deduce how high the 757 was because we know the speed of the aircraft in feet per second(780), the distance from the first and last poles to the impact point(559' and 1064'), and time it would take using the speed against these two distances(0.72 and 1.36 seconds).....The FDR sample rate is still fine enough to be able to get an exact altitude if we had the data. Maybe Mike needs another FOIA request?
Darth Rotor
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Not Dulles, Reagan National, which is just down the river on Rte 1 about three or four miles south of the Pentagon. Dulles is 15 miles to the west or so. (I used to do some heavy partying out near Dulles, away back in my misspent youth.)
DR
Been there many, many times myself. And actually the Pentagon is 0.8 miles from the northern end of runway 15/33 at DCA. I have a couple of good photos of the Pentagon on approach to 19(Mike at 911Myths is using one on his missile batteries page).
What I was saying is that the barometric pressure difference shouldnt be that great between the 2 airports. AA 77 took off from Dulles and the altimeter setting should be in the ATC transcripts during a clearance transmission...if we could get it, then we could ascertain the baro altitude(roughly) at impact.
gumboot
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Some observations...
First, the times are wrong - it's set at 1300hrs EDT. For now I'll assume the minutes are correct and that it's just set to 1300hrs instead of 0900hrs.
According to this, AA77 began the manoeuvre at 0934:03.
The following conversation takes place at NEADS at 0934:01 in the course of a call to Washington Centre:
This is the first time NEADS know that AA77 is even missing (note, no mention of hijack - Indianapolis Centre originally assumed AA77 had crashed).
By 0935:41 AA77 is 5400 ft, heading 271 degrees (due west). That's when the following information comes in to NEADS:
Now, by my estimates based on the NTSB released flight path, when AA77 was flying due west, I put it about 10 miles SSW of the White House, "deviating away". Allowing for time delay, slightly incorrect directions (later NEADS aren't able to identify where the White House is on their radar scopes), etc... it's safe to assume this aircraft mentioned above is AA77 (though NEADS don't know it).
Now where are the interceptors? By this stage JohnDoeX has already asked this stupid question once, and will ask it again 20 seconds later at 0936:01.
Well, first off, NEADS has only two sets of interceptors - 2x F15s at Otis and 2x F-16s at Langley.
The Otis fighters are chasing down AA11 which it is believed is heading for Washington DC, based on projected flight path (bear in mind, at this stage no one knows it was AA11 that hit WTC1).
Okay so the F-15's are chasing a phantom plane, and Langley are being scrambled. But that's 14m21s before NEADS know about this plane over Washington DC, so where are the F-16s at 0935:41?
Well this was the only mistake made by the air defense on the day. When no direction to intercept is given, fighters are normally directed to clear civil airspace ASAP. Remember, pre 9/11, NORAD only sent intercepts inside the ADIZ, which is off the US coast.
So the ATC handling the Langley fighters sent them east to a training area over the Atlantic Ocean.
NEADS realise this BEFORE they know about the aircraft "deviating away" from the White House:
So 29 seconds before NEADS find out about this aircraft near the White House, the Langley F16's are turned around and headed for Baltimore.
Right. And what happens once NEADS know about this new threat?
Notice how it's not clear if the aircraft is SE or E? But for an F-16 it's not a big difference, given their speed and missile range.
Also notice things don't happen instantaneously in real life? The NEADS intercept order comes 1m42s after being notified of the threat.
So where is AA77 when this order to intercept comes in? Well, I timed the actual recording of the above conversation (51 seconds). So assuming the F-16's begin to move the instant that conversation ends, the time is 0937:14.
The F-16 pilots hit their afterburners and are thrown back in their seats as their aircraft roar towards Washington DC.
AA77 is lined up, Hanjour passes the throttle through 75% power, 305Kt, just over 2000ft. He plunges the nose forward into the aircraft's final descent.
In less that 60 seconds everyone on board, and over 100 people on the ground, will be dead.
And it is worth noticing, according to this simulation the pilot's flight control is appalling. The yoke barely stays still for a second. He is constantly over correcting. When he hits power the rate of descent drops of drastically, meaning he didn't compensate for the extra lift by nosing down.
-Andrew
First, the times are wrong - it's set at 1300hrs EDT. For now I'll assume the minutes are correct and that it's just set to 1300hrs instead of 0900hrs.
According to this, AA77 began the manoeuvre at 0934:03.
The following conversation takes place at NEADS at 0934:01 in the course of a call to Washington Centre:
This is the first time NEADS know that AA77 is even missing (note, no mention of hijack - Indianapolis Centre originally assumed AA77 had crashed).
By 0935:41 AA77 is 5400 ft, heading 271 degrees (due west). That's when the following information comes in to NEADS:
Now, by my estimates based on the NTSB released flight path, when AA77 was flying due west, I put it about 10 miles SSW of the White House, "deviating away". Allowing for time delay, slightly incorrect directions (later NEADS aren't able to identify where the White House is on their radar scopes), etc... it's safe to assume this aircraft mentioned above is AA77 (though NEADS don't know it).
Now where are the interceptors? By this stage JohnDoeX has already asked this stupid question once, and will ask it again 20 seconds later at 0936:01.
Well, first off, NEADS has only two sets of interceptors - 2x F15s at Otis and 2x F-16s at Langley.
The Otis fighters are chasing down AA11 which it is believed is heading for Washington DC, based on projected flight path (bear in mind, at this stage no one knows it was AA11 that hit WTC1).
Okay so the F-15's are chasing a phantom plane, and Langley are being scrambled. But that's 14m21s before NEADS know about this plane over Washington DC, so where are the F-16s at 0935:41?
Well this was the only mistake made by the air defense on the day. When no direction to intercept is given, fighters are normally directed to clear civil airspace ASAP. Remember, pre 9/11, NORAD only sent intercepts inside the ADIZ, which is off the US coast.
So the ATC handling the Langley fighters sent them east to a training area over the Atlantic Ocean.
NEADS realise this BEFORE they know about the aircraft "deviating away" from the White House:
So 29 seconds before NEADS find out about this aircraft near the White House, the Langley F16's are turned around and headed for Baltimore.
Right. And what happens once NEADS know about this new threat?
Notice how it's not clear if the aircraft is SE or E? But for an F-16 it's not a big difference, given their speed and missile range.
Also notice things don't happen instantaneously in real life? The NEADS intercept order comes 1m42s after being notified of the threat.
So where is AA77 when this order to intercept comes in? Well, I timed the actual recording of the above conversation (51 seconds). So assuming the F-16's begin to move the instant that conversation ends, the time is 0937:14.
The F-16 pilots hit their afterburners and are thrown back in their seats as their aircraft roar towards Washington DC.
AA77 is lined up, Hanjour passes the throttle through 75% power, 305Kt, just over 2000ft. He plunges the nose forward into the aircraft's final descent.
In less that 60 seconds everyone on board, and over 100 people on the ground, will be dead.
And it is worth noticing, according to this simulation the pilot's flight control is appalling. The yoke barely stays still for a second. He is constantly over correcting. When he hits power the rate of descent drops of drastically, meaning he didn't compensate for the extra lift by nosing down.
-Andrew
Ok, just analyzed the FDR plot for AA77 for the last half hour or so.
http://www.911myths.com/AAL77_fdr.pdf
Couple of interesting things stood out.
First, the baro selectors were set to 30.20 for departure and then 29.92 after 18,000' as you might expect. However, sometime after the takeover and after initiating an autopilot descent, the #1 baro knob was set to around 30.25(somewhere between 30.20 and 30.30) descending through 15,000'.
Now, this might mean that the pressure altitude was fairly accurate, but did Hani set it exactly or just ballpark it. Using a pressure altitude calculator, I starting plugging in some numbers. If the baro knob was just .05 off, that leads to a 50 foot error.
Since JDX says AA77 was 180' over the lightploes, we'll go with that. Also, as I mentioned above, that area has a 37' elevation already and the poles were likely 30' or better. So thats 180-65= 115' of error - or - 0.12 inches of pressure. I am thinking that DCAs baro pressure was 30.13ish(Dulles was 30.20) and Hani didnt set it correctly(30.25), introducing an error in altitude data. I find it illogical that he changed it in the first place....
http://www.911myths.com/AAL77_fdr.pdf
Couple of interesting things stood out.
First, the baro selectors were set to 30.20 for departure and then 29.92 after 18,000' as you might expect. However, sometime after the takeover and after initiating an autopilot descent, the #1 baro knob was set to around 30.25(somewhere between 30.20 and 30.30) descending through 15,000'.
Now, this might mean that the pressure altitude was fairly accurate, but did Hani set it exactly or just ballpark it. Using a pressure altitude calculator, I starting plugging in some numbers. If the baro knob was just .05 off, that leads to a 50 foot error.
Since JDX says AA77 was 180' over the lightploes, we'll go with that. Also, as I mentioned above, that area has a 37' elevation already and the poles were likely 30' or better. So thats 180-65= 115' of error - or - 0.12 inches of pressure. I am thinking that DCAs baro pressure was 30.13ish(Dulles was 30.20) and Hani didnt set it correctly(30.25), introducing an error in altitude data. I find it illogical that he changed it in the first place....
I noticed this too, but JohnD'oh says...
Mr. D'oh said:
Who are we to argue with a pilot wannabe...?
If you need any more professional refutations of specific points, it might be worth posting at pprune.org in their Tech Log forum. Make clear why you're asking though, as they've had one or two CTers and many will be suspicious.
Darth Rotor
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True enough, it's just that I am fairly certain Reagan has its own reporting and recording criterion. When you dial ATIS there, you don't get Dulles QNH, you get Reagan QNH. Fifteen miles is far enough, depending on weather and particularly as fronts run through, for an altimeter setting to make a difference in the terminal phase.
The other problem is that acceptable altimeter error for a baralt, unless something changed recently, is IIRC per FAA standard within 75' of field elevation on take off. If my field elevation is 110 feet, and I set my altimter to 29.97 based on ATIS reporting baralt as 29.97, and I get an altitude on the bar alt reading between 185 feet and 35 feet, I am legit. If forget what acceptable Rad Alt errors are, I think it is in single digits of feet.
Of course, the lackwits at Loose Change, and elsewhere, don't bother to know any facts about aircraft instrumentation, they just throw crap out there.
DR
gumboot
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It is also worth noting that, IIRC, the highway itself was raised on something like a 15' berm... which would put you up to 80' or only 100' of error - 0.1 inches of pressure.
-Andrew
Darth Rotor
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1. You presume that from "turn it and burn it" line?
Turn it and burn it, or "turn and burn" is a bit of pilot slang that connotes making haste, however, you typically expect to hear a comment like "select Zone 5" or "use burner" or "approved/cleared for supersonic" or something like that if the F-16's are going to go supersonic. With no tankers in the air, the likelihood that the F-16's hit after burner are situation dependent. However, since there are plenty of divert fields in the area, Andrews, BWI, and others near enough, they might have gone supersonic. Not a bad guess, but not a dead certainty.
After burner eats gas like Pacman eats dots. Pilots have to manage their fuel ladder meticulously. Where do we have explicit statements from the pilots, ATC, or the NEADS crew that the pilots were using afterburner or were directed to do so, or cleared to do so? Fuel management means, among other things, if yuo run the fighters out of gas, you have no fighters on CAP until tankers show up. If they refuel on the ground, it takes a while to turn them around and get them back on patrol.
I imagine such a discussion is in part of the 30 hours of tape the reported listened to, but was not in the excerpts he put in the article?
Or, I missed it when I read it.
2. Given how little flight time in model the hijack pilot had, I do not consider his control inputs "appalling." They were rough, and he seemed to do a poor job of anticipating aircraft response. He did about par for the course, since his intuitive sense of leading control inputs and trim for power settings, and airspeed settings, put him slightly behind the aircraft. In a novice pilot, that tends to induce over correcting.
All things considered, he did well to hit his target.
DR
gumboot
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I was really just being dramatic...
However, after Nasypany found out the F-16s were heading over the Atlantic, with an aircraft 6 miles from the White House, he did tell Weapons to get the fighters to Washington as fast as humanly possible... as he said "I don't care how many windows you break goddammit!"
In addition, the lead pilot out of Otis said he went to afterburner on his way to New York because he "had a bad feeling about it".
Of course, I have no idea if they actually did go to afterburner... but you get the idea, just as they were powering up to get to DC, Hanjour was almost finished powering up AA77 for its final approach.
-Andrew
Darth Rotor
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OK, that tips me toward the next transmission being from the controller to the pilot to go supersonic. Nasypany has already considered the risks of fuel management and chosen to sort that out in due course, and try to catch up.I was really just being dramatic...
However, after Nasypany found out the F-16s were heading over the Atlantic, with an aircraft 6 miles from the White House, he did tell Weapons to get the fighters to Washington as fast as humanly possible... as he said "I don't care how many windows you break goddammit!"
In addition, the lead pilot out of Otis said he went to afterburner on his way to New York because he "had a bad feeling about it".
Thanks.
DR
EDIT: somethere in there, someone must have scrambled an alert tanker.
Last edited:
ghost707
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Well since the pressure altimeter is useless for altitude reference deviations of less than 100 feet, johndoe's argument is a red herring. That is why the automated ground reference callouts on approach are tied to the radar altimeter. I think the radar altimeter is accurate to within a foot or so.
I need to check that out
I need to check that out
gumboot
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I'd say so. Bearing in mind, from NEADS point of view there were 11 hijackings in the first 90 minutes and it didn't stop when UA93 crashed. From a very early stage they were prepping additional aircraft to establish CAPs with AWACS and tankers. They were basically calling every base they had to see what was available at short notice.
-Andrew
You guys are really boring me to death with all this tanker talk. I think we all know by now that if it did not play a prominent role in the movie Top Gun, then it's unworthy of discussion in an air defense readiness thread. [/sarcasm]
I can only assume that each AOC now has an alert tanker and airborne control platform at its disposal. I've been trying (with no success) to find out when the first tanker orbits were flown on 9/11 and what measures and when were undertaken to achieve that goal.
I can only assume that each AOC now has an alert tanker and airborne control platform at its disposal. I've been trying (with no success) to find out when the first tanker orbits were flown on 9/11 and what measures and when were undertaken to achieve that goal.
gumboot
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YeahI've never seen anything either... all I really know is by Wednesday morning over 300 aircraft were airbourne over every major North American city with AWACS and tankers in support.
I don't know if Operation Noble Eagle is still ongoing, but it involves permanently airbourne AWACS and tankers IIRC.
-Andrew
Darth Rotor
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*snort* The AWACS went to Afghanistan and the Gulf in late 2001 and got ridden hard, put away wet.
DR