AA77 FDR Data, Explained

mcMike said:
So we assume that FDR ends to T-1 ? I tought it was more since I saw some references to T-2 or even T-3. Could remember wrong though.
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The actual impact time, relative to the CVS file is quite difficult to say with certainty. The CTers will have you believe that :45.000000 is the actual impact time. JDX might even admit that it could have impacted as late as :45.999999. He's still not completely correct. The :46 time stamp made it onto the recording media, so the actual window is somewhere between +0 and +2 seconds after the end of the :44 frame.

Notice how careful I am in determining what "time" the :44 frame is. CTers would like to assume that the :44 frame starts at :44.00000 and ends at :44.999999. The chances of that being true are virtually nothing.
 
mcMike said:
15 posts finally. Now the link and point I was trying to make.

This:
http://img223.imageshack.us/img223/841/headingwr1.jpg

Since we can clearly see from FDR the heading is stable for last 10 seconds. It's kinda safe to assume that the plane was heading in direction of RED path or otherwise it would've missed the Pentagon alltogether.

I am trying to point out that the NTSB-animation and "wrong-path" can be debunked with heading alone. The absolute-positional information is apparently wrong and there are multiple reasons for this. But the heading should be quite accurate (in those speeds the wind doesn't matter a lot so the bearing and heading is about the same).

Any claims for "eyewitness"-path would require the plane to fly in 20-degree yaw which is quite impossible in that speed.
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That's actually a really nice graphic. I'm starting to think that this "heading" and "lightpole" issue might need it's own permenant spot on one of the websites as a frequently asked issue.

But yes, this does show fairly conclusively that the NTSB animation had the plane orientated with respect to magnetic north, and the map orientated with respect to true north. Once that correction is made, the animation would be correct. Beware, though, because saying the NTSB is wrong is a slipperly slope into logical fallacy land.


Reproduced, below:
headingwr1.jpg
 
beachnut said:
What is the source for the lat and long?

anyone find a radio altimeter setting, it would only be on low to the ground, 1000 feet or so, not sure if it like the KC-135 but Radio ALT would show relative height above the ground.
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The position data would either come from the Flight Management System(via IRS), or more likely, the Inertial Reference System itself. The error would probably stem from the way the data was recovered or recorded, and not from the IRU position data itself. There is absolutely no way AA77 would've taken off with that kind of IRS "drift" - trust me :)

FYI - the 757 RADALT unflags at 2500 ft AGL. So, it should've appeared in the last 30 seconds or so, but it wasnt recorded properly...or couldnt be confirmed as correct(I forget what the NTSBs wording was - I just read that section of the AA77fdr.pdf from 911myths yesterday).
 
the plane could be still hitting almost 6000 feet per minute and take out the light posts and hit the pentagon

look for angles of 4 to 6 degrees and you have 4000 to 6000 feet per minute

the heading is right with what happen, witnesses would help if you correlate them to their real positions

unless you really believe the parking lot video show enough for a flatter hit, not sure how you can take a 1 frame or half frame a second video low res far field video and make any decisions at all

if there are only 2 or 3 seconds left and the plane is really at 400 feet or so you would need 6000 feet per minute to fit, which is what the terrorist pilot was doing

The FDR is great for accidents, it shows you what was up, if this was an accident they would know it was not by the final approach and the throttles being pushed up, makes it on purpose

there is enough from the FDR and the video to back up what happen, unless you are a CT guy

then the little errors we live with everyday become some ct, if you are ct

The FDR gives us details now that debunk Charlie Sheen's super pilot theory, the terrorist did nothing a kid off the street could not do as good or better, the terrorist wasted money on training

the FDR debunks the 7 g expert ct guys, the plane barely did 1.7 g max

the final turn was rough, the descent from 7k to 2000 feet was an easy descent for any pilot

the FDR makes the ct world before the FDR look like idiots

So the NTSB used other data to place the plane on course, closer on course, bet they just moved the takeoff of the video over to the airport,

it would be great to have the exact position for the last second of FDR data, that would give us the time to hit, at 771 feet per second plus the final estimated speed at impact

then too you would have a better estimate on the vvi, rate of descent
 
apathoid said:
The position data would either come from the Flight Management System(via IRS), or more likely, the Inertial Reference System itself. The error would probably stem from the way the data was recovered or recorded, and not from the IRU position data itself. There is absolutely no way AA77 would've taken off with that kind of IRS "drift" - trust me :)

FYI - the 757 RADALT unflags at 2500 ft AGL. So, it should've appeared in the last 30 seconds or so, but it wasnt recorded properly...or couldnt be confirmed as correct(I forget what the NTSBs wording was - I just read that section of the AA77fdr.pdf from 911myths yesterday).
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you mean like KAL707 putting in wrong points or leaving them out'

actually you could safely fly the plane with out the fancy INS, or IRS. you could do it like you do in a C-172,

you do not need all that modern junk, the vor/dme still work and are good enough for flying, gee the road is 8 miles wide

so if it is something the pilots set and they decide to fly the airways using NAV aids and not the nav system of the plane they may have skipped updating the system and just flew the darn plane, you can do it

You would have to fake it if center gave you INS direct, but then pilots can do that also

I would takeoff, who need the fancy junk, just get me close to the airport for takeoff and landing.

lets go fly
 
beachnut said:
the plane could be still hitting almost 6000 feet per minute and take out the light posts and hit the pentagon

look for angles of 4 to 6 degrees and you have 4000 to 6000 feet per minute
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I'm not so sure about that. My calculations put the farthest hit pole about 1200 feet out. That's about 1.5 seconds by my calculations. If you assume a constant 4000 fpm dive, over 1.5 seconds, that's a descent of about 100 feet. Not sure if the top of the farther lightpole is 100 feet (or higher) compared with the final impact point.

However, the moment you don't assume linear trajectory, this entire argument falls apart. Also the fact that the 4000 fpm dive, by most CTers, is totally assigned to the wrong time. That 4000 fpm dive measurement is quite a bit older then they want you to believe. It's probably 3-4 seconds before the time of impact.
 
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beachnut said:
you mean like KAL707 putting in wrong points or leaving them out'

actually you could safely fly the plane with out the fancy INS, or IRS. you could do it like you do in a C-172,

you do not need all that modern junk, the vor/dme still work and are good enough for flying, gee the road is 8 miles wide

so if it is something the pilots set and they decide to fly the airways using NAV aids and not the nav system of the plane they may have skipped updating the system and just flew the darn plane, you can do it

You would have to fake it if center gave you INS direct, but then pilots can do that also

I would takeoff, who need the fancy junk, just get me close to the airport for takeoff and landing.

lets go fly
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Well, they could've flown without IRS, but not legally...It would be like an older generation airliner flying without its Vertical/Directional Gyros. Major no-go.
Of course, there are 3 IRUs so the odds of all of them failing are 'powerball lottery' odds.
 
Anti-sophist said:
I'm not so sure about that. My calculations put the farthest hit pole about 1200 feet out. That's about 1.5 seconds by my calculations. If you assume a constant 4000 fpm dive, over 1.5 seconds, that's a descent of about 100 feet. Not sure if the top of the farther lightpole is 100 feet (or higher) compared with the final impact point.

However, the moment you don't assume linear trajectory, this entire argument falls apart. Also the fact that the 4000 fpm dive, by most CTers, is totally assigned to the wrong time. That 4000 fpm dive measurement is quite a bit older then they want you to believe. It's probably 3-4 seconds before the time of impact.
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was looking at the final g readings and trends, I think he could have picked up to 6 or 7000 fpm or better then pulled back to 4000 fpm, he was pushing on the stick again

I think he picked up 6000 or more fpm then pulled out to make the hit

if he had to hit the pole, he had to get down quick at 100 plus fps, unless the plane is lower

need to find a real good altimeter setting for the pentagon at the impact time

wonder how an over speed affect the pitot static system and if Boeing modeled the errors for 463 KIAS,

Does the 757 have accurate altimeter readings at 463 KIAS?

There may not be proper error models in the air data computer for that speed near sea level!

But the darn things are usually so close in normal operations

darn study time, need best info on air data computer for over speed vs altimeter, plus other things
 
apathoid said:
Well, they could've flown without IRS, but not legally...It would be like an older generation airliner flying without its Vertical/Directional Gyros. Major no-go.
Of course, there are 3 IRUs so the odds of all of them failing are 'powerball lottery' odds.
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I call them INS, have not flown a 757

but the pilot, a navy guy ?, navy guys do not use anything, just blue sky and speed,

me not need IRS, me fly by seat of pants

serious, unless you know the plane was devoid of vor and dme, then the pilot could ingnore the offset on the IRS/INS or GPS

you put in the nav aid frequency, dial in the course and fly, I did it, you can do it\

is it against company policy or rules, who knows?

I did not say fly with out the ADI gyros, yes you have to have an ADI gyro unless you know the weather is clear, then you can use gods adi, the earth,

a little tongue in cheek but you can fly very well with the radio nav aids, they still work, and all the procedures to get in and out of airports are based on the radio nav aids, and I was flying in 2001, flew on 9/12 and 9/13 to pick up my fellow worker in OR, and get him back to CA since he was stuck when flying commercial was down for days.

The cops followed me when I got gas at Lincoln, who are u? they asked, guess everyone was real jumpy the next day, or two,

anyway, just junk on flying, but I would not be surprised if they did ignore the IRS,

but then I am an old pilot, but if 77 pilot was navy, he may not of even bothered with the IRS junk, it is extra work anyway, in a way

just my one cent worth, want to go fly?
 
beachnut said:
I call them INS, have not flown a 757

but the pilot, a navy guy ?, navy guys do not use anything, just blue sky and speed,

me not need IRS, me fly by seat of pants

serious, unless you know the plane was devoid of vor and dme, then the pilot could ingnore the offset on the IRS/INS or GPS

you put in the nav aid frequency, dial in the course and fly, I did it, you can do it\

is it against company policy or rules, who knows?

I did not say fly with out the ADI gyros, yes you have to have an ADI gyro unless you know the weather is clear, then you can use gods adi, the earth,

a little tongue in cheek but you can fly very well with the radio nav aids, they still work, and all the procedures to get in and out of airports are based on the radio nav aids, and I was flying in 2001, flew on 9/12 and 9/13 to pick up my fellow worker in OR, and get him back to CA since he was stuck when flying commercial was down for days.

The cops followed me when I got gas at Lincoln, who are u? they asked, guess everyone was real jumpy the next day, or two,

anyway, just junk on flying, but I would not be surprised if they did ignore the IRS,

but then I am an old pilot, but if 77 pilot was navy, he may not of even bothered with the IRS junk, it is extra work anyway, in a way

just my one cent worth, want to go fly?
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"Chic" Burlingame was a Navy guy ;)

There is an alternate mode of IRS operation called "ATT", or Attitude Only, which removes all heading/ position info from the displays and leaves the EADI operable.. I imagine this would be one of the things the FDR would look for. You can probably dispatch a 757 with 2 of 3 IRUs operable, but the inoperable units circuit breaker would be pulled and collared prior to flight, so its invalid data would never have made it to the DFDAU..
 
but it would not be legal to fly IFR without the right amount of gyros required per regulations, (not current on them)

I flew some instuments in the weather in a small plane and finally figured out the instrument are junk and that perked up my crosscheck, all of a sudden the ancient instruments became very important, as a cross check of who (instrument) is right and making sure they stay that way

needle, ball, and airspeed

not that you would do it, but if you can ignore the funciton of navigation and live with some offset and still have good gyros it would be safe to fly

you have to know your systems (limitation etc), but I have no idea if all the crap I said would hold up as being relavent in a 757 system better find some facts first before I bore u to death,

I know some current airline guys, but it has been years, I could check, but the time could be weeks for hooking back up
 
Anti-sophist said:
However, the moment you don't assume linear trajectory, this entire argument falls apart. Also the fact that the 4000 fpm dive, by most CTers, is totally assigned to the wrong time. That 4000 fpm dive measurement is quite a bit older then they want you to believe. It's probably 3-4 seconds before the time of impact.
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need 5 or 6 seconds, think you can firm up the frames being stored 4 seconds after happening?

if you move the data into the past 3 or 4 seconds, you are saying the process of getting the data into the survivable part of the FDR, ie the FDR, takes 3 to 4 seconds, which could be possible,

the data is compressed and processed, but why not fast?

if that is true and the plane is at 460 msl at the last FDR entry, then the pilot is trending towards 6000 fpm,

n+1 360 msl 6000 fpm 6 degrees down
n+2 260 msl
n+3 160 msl
n+4 60 msl

I have no problem with 4000 fpm and I think that could have the aircraft hit the lights, 4 degrees would be close with variation, or a lucky pullout if we have more time

need over 4 seconds unless you let him panic dive for a second and recover in a second and then hit at 4 degrees

if the data is stored 3 to 4 seconds late, then you have 5 to 6 seconds and NTSB video path needs to back off the correct distance, not so sure the map is sync in any way

okay, how do you find out how old the stored frame is compared to the end of data etc

(i just remembered how the different clocks at the pentagon had CTers jumping all on time)

I was in the air force, our office clock was set to justify, or rationalize, leaving early or arriving late, end of story!

our watches were on by a second since 1978! unless you had an air force issue wind up, we did save you guys the bucks!

CT guys are funny

– need to verify data age and storage, if it is 3 to 4 seconds old, and the final time stamp is impact time or earlier, you have it

plus the position error, and ground sync error

do I have to read all of your stuff to see if you already said it is 3 or 4 seconds (firm), I know you talked about those things but with UT, not so sure if he was on the same page or just like me, looked it up and getting hung up on details and not making correct judgments when required to compare what you said with what he is learning or what he knows

would be cool if he said which he has, recent learning, or he knows the stuff all along!

I am a pilot, and I have instructed in the AF, but I have to look it up and get back to you, if I was in the nuts and bolts of the FDR.

Need to hire Boeing
 
Did I understood this correctly? Nobody knows (not even NTSB) when the last frame was recorded prior to impact? They just adjusted the timescale in FDR-data to match T-1 or T-0 before impact?

If this is true then there can be even 5 seconds missing from FDR and we nor JDX can't say or analyse anything for the last altitudes, accelerations etc. So the whole FDR-thingy is pointless for any argument?
 
unless you believe flight 77 is still airborne, the last atltiude could be 460 feet msl and the pentagon is at 38 I think, have to check

there are two time stamps empty on the FDR

9:37:440.6630.1320.0311730.6180.1410.0110.6270.137-0.1760.6860.134-0.0220.7570.6130.7160.6189:37:459:37:46

the 173 is final altitude based on 2992, the local was 30.20 or so you have to add 300 feet or so
 
that came out bad


9:37:44 this had data but the next two time stamps had nothing

9:37:45
9:37:46
 
beachnut said:
not that you would do it, but if you can ignore the funciton of navigation and live with some offset and still have good gyros it would be safe to fly

you have to know your systems (limitation etc), but I have no idea if all the crap I said would hold up as being relavent in a 757 system better find some facts first before I bore u to death,

I know some current airline guys, but it has been years, I could check, but the time could be weeks for hooking back up
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I'm not a B757 pilot, but I'm probably the closest thing to a 757/767 expert here ;)

This is from the 757 MEL. You do need 2 of 3 IRUs operable to dispatch. Also, the inop unit must be deactivated(breaker pulled, collared and placarded). I'm leaning toward the position error being introduced sometime after the data was sampled, possibly after the data was recovered.

990245407d129a385.jpg


beachnut said:
okay, how do you find out how old the stored frame is compared to the end of data etc
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That is a great question and if I read A-S correctly, its really difficult to say from what we have(the CSV). I just want to know in what friggin box the time stamp takes place in. Ive read(through) 400 pages of FDR/FDAU manuals and cant find a single mention of it.
 
not to lay down too much BS

I was trying to say the position could be off by what we see, yet the gyros are good

My navigator load the our INS with 17 south instead of 7 south, we were, 600 miles off, he got pissed and dumped it

he could of left it running and used it as a rough offset to back up his cel nav,,,,,,,,,

so if it is possible to have the nav system align offset and stay, and the pilots either entered the beginning start point 20 miles in error, but they are not using the internal navigation but the vor radio nav aids which they have to use anyway, why waste time on your computer nav

this would account for the 20 mile offset

I know the nav system can be set up at the wrong initial point, my crew did it, now is that possible with this system?

I understand what you have on the go no go, and you are correct but it does no preclude setting up the wrong inial point in the nav computer, the gyros do not care, that much

our INS need 20 minutes running in one spot to work best, and yes, when you set it up 600 miles wrong, there are some problems and error modeling in the software i imagine will not work very well but the ins gyros are still good for attitude.

I think it is possible to align 20 miles off, not sure if it would hold, but that would account for our offset in the FDR, and it was relative in error if you move the takeoff point back to the real airport, placing the takeoff at the correct airport and the end point over the pentagon

and I think it bears more time to investigate, and I do agree with your chart, it is the chart and I do not believe it precludes the pilots setting or accepting a 20 mile offset error in the nav system

does this make sense
 
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