9/11 P4T FDR analysis of flight 77

chris lz

New Member
Though I did a check of all the thread titles, kindly let me know if I somehow missed this.

P4T's analysis of the FDR for American flight 77 (and UA 93) has received relatively less attention from debunkers, most of it scattered in little bits over the www, especially in hard to sift through nooks and crannies over at JREF. If the more technically inclined think it's worth it, I would very much welcome an overview and summary of the main objections to their findings.

Chris
 
Though I did a check of all the thread titles, kindly let me know if I somehow missed this.

P4T's analysis of the FDR for American flight 77 (and UA 93) has received relatively less attention from debunkers, most of it scattered in little bits over the www, especially in hard to sift through nooks and crannies over at JREF. If the more technically inclined think it's worth it, I would very much welcome an overview and summary of the main objections to their findings.

Chris
Please perform a site search in the upper right corner of the page. My results can be found here at https://www.metabunk.org/search/1527399/?q=p4t&o=relevance
 
Please perform a site search in the upper right corner of the page. My results can be found here at https://www.metabunk.org/search/1527399/?q=p4t&o=relevance


Hmmm, when I do that, the only thread with this topic that comes up is this one. I also did a site search for "flight 77." Also did Google search with same, no matching results.

Do you remember a specific thread name by any chance?

edit: just to clarify, I am talking about this specific debate:
http://scienceof911.com.au/pentagon/rebuttal/
 
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No, I don't think it's there. I read the entire 9 page thread above earlier today.

P4T had their resident FDR tech person decode the FDR file for F77, and concluded the last data on the recorder puts the plane too high and north of the Pentagon. Very little has been discussed by debunkers, at least that I can find. P4T writes:

CSV file and animation as plotted and provided by the NTSB through the Freedom Of Information Act (1) at time stamp 09:37:44, reports pressure altitude as 173 (csv file) and 180 feet (animation). When adjusted for local pressure to true altitude, the aircraft is ~473 and ~ 480 feet above sea level, respectively. Too high to hit the light poles as reported being struck on Washington Blvd and the Pentagon if trends are continued. NTSB calculates and reports impact time of 09:37:45 in their NTSB Flight Path Study (2).
Content from External Source
 
No, I don't think it's there. I read the entire 9 page thread above earlier today.

P4T had their resident FDR tech person decode the FDR file for F77, and concluded the last data on the recorder puts the plane too high and north of the Pentagon. Very little has been discussed by debunkers, at least that I can find. P4T writes:

CSV file and animation as plotted and provided by the NTSB through the Freedom Of Information Act (1) at time stamp 09:37:44, reports pressure altitude as 173 (csv file) and 180 feet (animation). When adjusted for local pressure to true altitude, the aircraft is ~473 and ~ 480 feet above sea level, respectively. Too high to hit the light poles as reported being struck on Washington Blvd and the Pentagon if trends are continued. NTSB calculates and reports impact time of 09:37:45 in their NTSB Flight Path Study (2).
Content from External Source
The last point pilots for truth decoded was 173, and the RAD ALT reads 233 - pilots for truth are missing 4 seconds of data. Means the quote you posted was 4 seconds away from impact. Pilots for truth are wrong, for reality reasons, Flight 77 did hit the lampposts, and Flight 77 did hit the Pentagon. Not sure why they fail to realize data was missing, and decided to spread false information. How can 77 be to high to hit what 77 hit? Amazing anyone uses what pilots for truth say when they are wrong due to evidence.

Pilots for truth are wrong, Flight 77 was 4 feet above the ground on the last data point on the RADAR ALT. ... Pilots for truth decode is missing 4 seconds. They have the RAW data but failed to finish the decode.

The quote you posted is silly, it makes no sense.The FDR data they have, plots 77 4 seconds away from the Pentagon impact - pilots for truth were told this years ago, but never corrected their errors. Instead they attack the person who decoded the rest of the FDR.
With the final four seconds the pressure altitude is -99, radar altimeter is 4. Too low not to hit the lampposts which were knocked down by 77.

http://scienceof911.com.au/pentagon/rebuttal/
It looks like you debunked pilots for truth with this reference.
 
[Keith Beachy said:
[url]http://scienceof911.com.au/pentagon/rebuttal/[/url]
It looks like you debunked pilots for truth with this reference.

To be debunked by a truther doesn't always leave one feeling as confident as one would like. Not being an FDR expert, I invite anyone else to review the link above.

There was discussion at JREF (as I'm sure you recall) by AntiSophist regarding the misuse of the raw CSV file for these purposes. Does this still apply to the successful decode by Legge and Stutt in the above link? I'm presuming they used the same source (no?)

cheers
 
Besides the P4T errors in their "analysis" of the AAL77 FDR at the last moments, there is also their epic failed "announcement" that the FDR info must have been "faked" because the flight deck door was recorded as "closed" continuously. They gleefully harped on this "fact" for months.

Turns out that the parameter of the door latch position simply was not recorded by the FDR on that particular airplane at that time. The null or default parameter for that data point was "closed".

There is also a very ridiculous screed about the ground track plotted at IAD, from pushback to the taxi and takeoff. Contention that the position information recorded didn't "match" the actual Lat/Long coordinates of the airport and various pavement locations.

This is easily dismissed due to the inherent inaccuracies of the IRS platforms in that era of pre-GPS position updating. (Non-GPS) IRS present position updating is more accurate after takeoff, 'accurate' IRS position info simply isn't a factor for ground operations. (ETA: I decide to edit here to clarify something that is common in the modern, GPS-era today. Accuracy of position (with GPS-updating) IS now a factor in ground operations....though it wasn't in 2001. Accurate GPS position info is used by the EGPWS, or Enhanced Ground Proximity Warning Systems, in a variety of ways, to include reducing the chances of runway incursions during taxi, especially in low visibility, and to provide "runway distance remaining" info during the landing roll-out...among other features).

Airline pilots familiar with these airplanes and their systems rightly ridicule such P4T claims. Unfortunately, these facts are blurred by P4T in their efforts to bamboozle and dazzle the laypersons in their "audience".
 
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To be debunked by a truther doesn't always leave one feeling as confident as one would like. Not being an FDR expert, I invite anyone else to review the link above.

There was discussion at JREF (as I'm sure you recall) by AntiSophist regarding the misuse of the raw CSV file for these purposes. Does this still apply to the successful decode by Legge and Stutt in the above link? I'm presuming they used the same source (no?)

cheers
The CSV file? What do you mean? The comma-separated values files is already decoded, you can read it in excel, or any program you can import CVS files. The raw data is described in the raw file and you would have to have the descriptors to decode it. What was the misuse issues?

I have the decode, it debunks pilots for truth, Stutt's decode debunks pilots for truth. Stutt decoded the FDR based on data descriptors he looked up, and all his work was transparent, he presented all his data, all his descriptors he got through FOIA; you could follow his work and see it is correct - your link debunks pilots for truth, no matter who did it because you can follow their work and do it yourself.

pilots for truth decode matches the NTSB minus one second, and Stutt's work match both plus 5 and 4 seconds. The pilots for truth decoded one less second, Strutt decoded 4 more seconds. Might have something to do with frames; a frame is 4 seconds, if pilots for truth decoded by frame with some existing software, the software would stop when frame errors are encountered, or some anomaly which stopped the NTSB and pilots for truth 4 to 5 seconds short of the end of data - the data kinds of ends at impact, there is most likely an incomplete frame at the end. See Stutt's work for the real story on this factor. Stutt's decode, he was able to program around the missing data, or problems and go to the end.

Pilot for truth claims are refuted by the lampposts - no need to decode the FDR. The claims are debunked by RADAR and eye witnesses. Pilot for truth claims are debunked by the DNA, by the damage to the Pentagon done by the kinetic energy weapon a 757, the jet fuel fireball is evidence too. It gets silly when they make up claims already debunked by evidence. They were told the seconds were missing based on the existing decode by the NTSB, and pilots for truth decode.

Who is truther who debunked pilots for truth? Legge, able to use the FDR to debunk pilots for truth; yet he believes in CD, thermite and silent explosives - his science ends at his fantasy of CD. It is ironic when 911 truth is debunked by "911 truth". The decode of the FDR final seconds is proof. The decode is correct because it matches the NTSB and pilot for truth decode. When 911 truth followers finally use math and physics, they usually stop being 911 truth followers. Not sure why Legge can apply science to this BS, but he supports the same kind of lies from Gage, anti-science.

I have a copy of Warren Stutt's decode for 77 - not sure where it exists on the Internet now, old links are gone. He was open with his decode.

Pilots for truth take the impact time of 09:37:45 as exact, and argue it is right, absolute, yet imply the FDR is fake. Logic does not exist in 911 truth, and errors in logic like this are proof something is wrong with 911 truth. The NTSB was not tasked to solve 911, or an accident, they were tasked to support the FBI; I think the FBI wanted to know how the terrorists flew, and the NTSB ran the software which stopped when the last frame or so was missing data, which would have bad check sums. The NTSB was not tasked to find out where 77 crashed, the FDR answered that explicitly, where it was found.

Wait, pilots for truth say, "Too high to hit", but the FDR was in the Pentagon and Flight 77 was all over the Pentagon, exactly how a 483.5 knot crash would look - the exact damage a 757 would make. pilots for truth were debunked before they started.
 
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A post at JREF which talked about the pitfalls of using the CSV file, which at the time (2006) was the only usable data source. But from the re-reading the Legge paper, it seems that sometime later, the tools to decode the raw data file became available.

see http://www.internationalskeptics.com/forums/showthread.php?t=66047&page=1

Appreciate the expert confirmation of the Legge/Stutt paper.

I appreciate the reasons to "ask"....based on the MANY...and I should emphasize MANY past implications, notions, and (just because I run out of synonyms) NONSENSE claims that have been perpetuated since 11 September, 2001.

The so-called 'CT' claims, as a rule, have been addressed countless times.

The major problem (today, and this is a personal observation) is that MOST of these older, ALREADY refuted claims still exist, because of the INTERNET. Meaning, the "internet" is still here....and, old crap remains, regardless of its veracity.

It then becomes incumbent on those who "read" the old "junk" on the Internet to properly "vet" the content.
 
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As Keith points out, the downed lamp posts indicate a large aircraft passed by low enough to take them down. That indicates impact right there. Thus PfT has had to postulate unseen "agents" running around taking down lamp posts. They also find they must postulate a fabricated DFDR that they further postulate has a different flight path than the supposedly faked flight (the unwitnessed fly-over).
In addition PfT's past utter failures, including a comical (mis)application of physics known as the 11 g paper, lends itself to call into question any credibility they may have had.
 
Not only that, someone in a car very close to the lamp posts saw a big plane take them out. It was seen.
Several people, some of whom PfT use as witnesses to supposedly support the PfT scenario, explicitly state that the aircraft hit the building.
 
This is easily dismissed due to the inherent inaccuracies of the IRS platforms in that era of pre-GPS position updating. (Non-GPS) IRS present position updating is more accurate after takeoff, 'accurate' IRS position info simply isn't a factor for ground operations. (ETA: I decide to edit here to clarify something that is common in the modern, GPS-era today. Accuracy of position (with GPS-updating) IS now a factor in ground operations....though it wasn't in 2001. Accurate GPS position info is used by the EGPWS, or Enhanced Ground Proximity Warning Systems, in a variety of ways, to include reducing the chances of runway incursions during taxi, especially in low visibility, and to provide "runway distance remaining" info during the landing roll-out...among other features).

I am not an avionist and i dont get your point in this GPS thing. What is a factor? Did the plane have a GPS-system onboard?
Where can i find the raw material and a program to extract the flight data until it hit the pentagon?
 
I am not an avionist and i dont get your point in this GPS thing. What is a factor? Did the plane have a GPS-system onboard?
Where can i find the raw material and a program to extract the flight data until it hit the pentagon?
No GPS on Flight 77.

The data from the NTSB...
http://www.ntsb.gov/about/Documents/AAL77_fdr.pdf
decoded by the NTSB, missing 4 seconds

I would have to look up the other data, I have the raw data somewhere on one of our home computers. I would have to search for the online sources. See above there are some references to the work done by wstutt, on decoding.
Found Warren's stuff, not sure where the raw data is. There was an iso file, It think, still looking (back burner)

More on his decoding -
http://www.warrenstutt.com/AAL77FDRDecoder/index.html
http://www.warrenstutt.com/AAL77FDRDecoder/NotesOnParameters.html
http://www.warrenstutt.com/index.html
 
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Thank you! I will have to take a closer look to these links.
No GPS on Flight 77.
So is it true then, that FDR data provided by the NTSB stated that GPS was operational?
And that the Pilots didn't recalibrate the INS before start, as required for a non GPS Plane?

Is it true, that the data shows, that the flight took of from a gate different from the one officially stated?
 
Thank you! I will have to take a closer look to these links.

So is it true then, that FDR data provided by the NTSB stated that GPS was operational?
And that the Pilots didn't recalibrate the INS before start, as required for a non GPS Plane?

Is it true, that the data shows, that the flight took of from a gate different from the one officially stated?

Who's making these claims? What exactly do they say and where do they say it? What evidence do they provide?
 
Thank you! I will have to take a closer look to these links.

So is it true then, that FDR data provided by the NTSB stated that GPS was operational?
And that the Pilots didn't calibrate the INS before start, as required for a non GPS Plane?

Is it true, that the data shows, that the flight took of from a gate different from the one officially stated?
NTSB did not say the GPS was operation, it was not installed. 77 had no GPS.

The Navigation system was initialized before takeoff, it has errors up to 2000 feet, and in the "old days" of ins only crossing of the ocean, two to six miles errors were accumulated. 77 used DME/VOR to correct the position over time.

The official gate is confirmed because ground controller said 77 taxied from a certain gate, and the navigation position has errors, so the crew does not care where the INS says they are on the ground, they can see with eyes to navigate the taxi to the runway, they don't use navigation to taxi, they have eyes.
77 did not take off from a gate, they taxied from a gate to the runway using their eyes; the official gate is where they taxied from in the real world.

An INS is not perfect, it can start with a 1/4 mile error from INS only, and INS only can drift up to 2 to 6 miles on a long mission.

Yes, the FDR navigation fixes show 77 from a different gate, and off the runway at takeoff, I think 1000 to 2000 feet to the south of the takeoff runway. It is reality of the navigation system in 77.
Pilots for truth make the claims about the navigation, thinking it is exact. They said 77 was at a different gate, and other nonsense, and ignore the evidence. Pilots for truth ignore system errors in the navigation system. An INS does not start at the exact place you tell it is at, it has to align, and during alignment errors in the system keep it from being exact.

Notes on navigation accuracy:
Lindberg used dead reckoning and made it to Paris using a compass.
Using celestial navigation with a sextant, as long as we were less than 25 miles off course when approaching land, we were okay, and fixes could be a accurate as a mile.
VOR and DME, errors of a half mile, or 3 percent of the distance from station were inside the system errors.
INS, 1/4 or less start error, 2 to 6 miles crossing the ocean.

If you are concerned about accuracy, the airways in the past were 8 miles wide... using GPS has caused accidents, because GPS is so accurate both planes going opposite directions at the wrong altitudes hit. Now there are procedures to alter flight paths left and right to avoid this kind of super accuracy accident, where being right is not a good thing when other things are wrong.

In this thread, plots of some of the 24 hours of FDR navigation points are plotted, note the errors in actual position. http://www.internationalskeptics.com/forums/showthread.php?t=202034

Here is 77 pushing back from Dixie 26 - the spot 77 was in, for real on 911.

Confirmed by 77's pilot, and ground control who is watching from Tower, all verbal testimony, proving 77 taxied from D-26. The navigation system drifts, has errors, these are facts, reality.
 
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If you are concerned about accuracy, the airways in the past were 8 miles wide... using GPS has caused accidents, because GPS is so accurate both planes going opposite directions at the wrong altitudes hit. Now there are procedures to alter flight paths left and right to avoid this kind of super accuracy accident, where being right is not a good thing when other things are wrong.

Why dont they derive a formula for the the exact flight altitude like : floor(Altitude they were told/400)*400+(heading-180)ft? dont they have about 400ft high airways nowerdays?
That would cause them to be at different altitudes if they fly in different directions. Cant they measure the altitude sufficiently enough to make sense of this?

Who's making these claims? What exactly do they say and where do they say it? What evidence do they provide?
P4T say that they got the FDR data from the NTSB that would explicitly say that GPS was "OPER" and that the gate position of the flight belonging to the data was i think it was C19.

How accurate is this INS with respect to the previous calculated position? Does it walk of over time or over space travelled?
 
P4T say that they got the FDR data from the NTSB that would explicitly say that GPS was "OPER"
I guess this is a case of the FDR recording a value for which there is no input. "GPS OPER" is a 0/1 field. If the FDR stores it, it has to store either 1 or 0, even if no GPS is even installed, or if it feeds no data to the FDR. So you read out some default value. If 1 is the default, that's what you read.
IIRC, there was a similar issue with the "cockpit locked" flag. P4T pointed out that the door had remained shut during he flight according to the FDR and that therefore no terrorists could have had entered and taken over the cockpit. But looking back at the enture 24 hour log you can see that the flag ALWAYS indicates "door locked" - which is unrealistic, pilots get coffee and step out to pee. Solution is easy: That batch of FDRs recorded "door locked" by default, but no signal was actually fed from door lock to FDR.

and that the gate position of the flight belonging to the data was i think it was C19.

How accurate is this INS with respect to the previous calculated position? Does it walk of over time or over space travelled?
Read Beachy's previous post again:
AA77 was off the runway by some 1000 feet according to recorded INS. They must have been some 1000 feet off the real gate then, too.
 
Read Beachy's previous post again:
AA77 was off the runway by some 1000 feet according to recorded INS. They must have been some 1000 feet off the real gate then, too.
Reed MY original post again:
How accurate is this INS with respect to the previous calculated position?
The question is how much does INS walk off between the steps.

I thougt you are a chemical debunker?! :)
 
Why dont they derive a formula for the the exact flight altitude like : floor(Altitude they were told/400)*400+(heading-180)ft? dont they have about 400ft high airways nowerdays?
That would cause them to be at different altitudes if they fly in different directions. Cant they measure the altitude sufficiently enough to make sense of this?

P4T say that they got the FDR data from the NTSB that would explicitly say that GPS was "OPER" and that the gate position of the flight belonging to the data was i think it was C19.

How accurate is this INS with respect to the previous calculated position? Does it walk of over time or over space travelled?
There are rules for altitudes already, and they work; the accident aircraft were assigned, or were at the wrong altitude; a mistake; and since they were exactly on course, and in opposite directions, they hit.
3-9. STRATEGIC LATERAL OFFSETS IN OCEANIC AIRSPACE TO MITIGATE COLLISION RISK AND WAKE TURBULENCE. Pilots should use the Strategic Lateral Offset Procedure ... In relation to a route or track, there are three positions that an aircraft may fly: centerline (CL) and 1 or 2 NM right. ... Reducing Risk. The intent of this procedure is to reduce risk (increase the safety margin) by distributing aircraft laterally and equally across the three available positions. In this connection, pilots must take into account the following: • Aircraft without automatic offset programming capability must fly the CL. • Aircraft programmed with automatic offsets may fly the CL or offset 1 or 2 NM right of CL to obtain lateral spacing from nearby aircraft. ... http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC 91-70A.pdf
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Pilots for truth are wrong, the GPS was not installed, and the FDR values for GPS was not verified, or not used; it does not matter what the bit was set to. It means nothing.

The INS is aligned by putting in the present position, after alignment it starts to operate, and as seen by those who plotted 77's position, it is off, what was it 2400 feet off. Don't get upset about accuracy, during flight 77 days in service, the airways were 8 miles wide, thus being 1000, or 2000 feet off real position, is safe inside the "airway".
The INS drifts, and the system in 77 used DME/VOR to update the INS/navigation system, which keeps the INS as accurate as DME/VOR or DME/DME. With accurate fixes from DME, the nav system will update slowly to remain as accurate it can be.
The positions would be relative to motion, and the system is updated to stay accurate. Typical system drifts when not aided by GPS, DME, or VOR/DME - when INS/IRS/FMC is not aided with outside updates it drifts up to 0.6 NM per hour.

The question is how much does INS walk off between the steps.

I thougt you are a chemical debunker?! :)
How much walk off? Unaided the system could drift 0.6 NM per hour, or 1.01 feet/second...
Corrections are made slowly from DME/VOR, and DME/DME. DME/DME is more accurate.

Chemical debunker? I am a grandkid babysitter, retired USAF pilot, and retired engineer, worked at AFWAL, Air Force Wright Aeronautical Laboratory (Wright-Patterson AFB, OH); I did make As in Chemistry, and I flew the day after 911, and 2 days after 911 to pick up my office-mate stuck due to commercial flights being grounded.

There is no point to the claims from pilots for truth, no reason. 77 took off on 911, tracked by Radar from takeoff to impact by multiple Radar sites. All but the small kids DNA was found in the Pentagon, on the course found in the FDR.
 
The 757/767 Flight Management System (FMS) does not fly via the IRS unless it has nothing else to use, i.e. long overwater operations.

The IRS position begins to drift from the moment the system is initialised. One of the procedures I had when flying the aircraft (767) was to do a "quick alignment" towards the end of the flight preparation procedure. This was an acknowledgement that the initial datum would have moved during the preflight. (Turning the IRS's on was one of the first things you did when you started pre-flight checks).

The inertial position would be updated to the runway threshold automatically on the selection of take-off thrust. This was the last time during the flight that the IRS position would be accurate.

So how did the aircraft navigate accurately? The aircraft derived its position from a variety of navigational inputs into the FMS. The most accurate of these is GPS, which was not fitted on the 767's I flew till late in the production run and apparently not on AA77 either, followed by DME (distance measuring equipment), VOR's ( a radio Nav beacon) Localisers which are another form of beacon used in the Instrument landing system) and finally the IRS position.

As the aircraft flies, it checks and cross references all these navaids and derives the most accurate position. This is known as the FMS position.

So the IRS position would have been drifting from initialisation till takeoff, and then till the crash. This is why errors are apparent and why they don't mean anything. Anything meaningful in the report should refer to the FMS position, not the IRS position.
 
DME (distance measuring equipment), VOR's ( a radio Nav beacon) Localisers which are another form of beacon used in the Instrument landing system) and finally the IRS position.

If I may enhance what "TWCobra" accurately stated?

Prior to installation of GPS-updating (which is nearly 100% common, nowadays as even older airplanes are retrofitted) the "location", as determined by the IRS units (very sensitive and better than the earlier versions, which used actual physical gyroscopes, called "INS")....the "IRS" use what are called "Laser-Ring" gyroscopes....no moving parts, aside from the laser light beam. By equipping three "dimensions" of the laser-beams, for each unit....every minor movement of the airplane is measured, and calculated....as the laser beam "shifts" ever so slightly...even a a fraction of a millimeter can be measured. This information is used (by these units) to determine acceleration in all three axes (plural of "axis", pronounced "Aks-Sees").

Back to the "IRS" units. On the Boeing 757 there were three installed, and each was "independent", except that they DID provide a "mix" of their location info....which is called the "FMS Position".

As mentioned by "TWCobra", each individual IRS Unit can encounter natural errors (minor, usually...unless there's a malfunction, in which case it will be "dropped" out, and the crew alerted). Prior to GPS updating (far more accurate) "TWCobra" described how each unit used ground-based signals to constantly update and improve and correct any errors that might accrue.
 
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