AA77 FDR Data, Explained

[Anti-sophist]

I don't think there is that many data points missing. My best guess is 1-2, so 2 at the most. The problem, of course, is the altimeter is not correct because it's not calibrated for those speeds and pressures.

If you have a way of quantifying the altimeter error given the airspeed, I'd love to see it. From my initial research on the issue, I thought that question was a non-starter.

 

[beachnut]

I don't think there is that many data points missing. My best guess is 1-2, so 2 at the most. The problem, of course, is the altimeter is not correct because it's not calibrated for those speeds and pressures.

If you have a way of quantifying the altimeter error given the airspeed, I'd love to see it. From my initial research on the issue, I thought that question was a non-starter.

I think I can find the general trend of errors based on speed in my books. I still have computer runs from 1970. I have punch card to program in fortran from 70-74. I must have my UPT books some where.

I have KC-135 dash-1 some where in the house.

I will search for the stuff.

 

[GlennB]

...

The FDR Raw Data File

A raw data file is only useful if also given the frame description, which describes the synch words, and the location inside of each frame for each recorded value. This frame-description was included in the NTSB report, according to the NTSB Flight 77 FDR report, page 2, footnote 1:

Based on Boeing’s 757-3B data frame. See Attachments IV and V. Boeing Document D226A-101-3, Rev. G, October 27, 1999 (D226A101-3G.pdf); American Airlines database printout (757-3b_1.txt)

To the best of my knowledge, none of these documents exist in the public domain, and were not released with the FOIA request. Without the frame description information, the raw data is almost entirely useless.

The only issue is to what extent can this file be reverse engineered, and what useful data can come from it. First, and most importantly, I am not sure if this data file has been uncompressed. The Flight 77 FDR report mentions (page 3) that specific software is necessary to uncompress the data. If the data in this file is compressed, then there is virtually nothing useful to be gained, without first uncompressing it. Given a brief look at the header of the raw file, it appears to contain plain-text, which would imply it was not compressed data.

Under the assumption it is uncompressed, already, I will speculate, briefly, on the potential gain from reverse engineering it. First, it’s very likely that someone with minor amounts of effort could figure out the synch words, and extract the major and minor frames in raw format. In this sense, you could get “frame lock”. You’d be able to align all the data between frames. This may be useful in determining the number of frames, or the state of the final few frames. Extracting any information, beyond that, would be incredibly difficult to pull off successfully.

...

You might be interested to know that "Snowygrouch" of the UK forum claims to have the raw data file *with data frame layouts* and is a few days work away from decoding it (allegedly)

http://www.nineeleven.co.uk/board/viewtopic.php?t=6242

(hope this isn't old news - I haven't read this entire thread)

 

[Anti-sophist]

That is news. I'm impressed that someone is actually making forward progress on the issue.

The data frame layout is only half the battle. They also need the conversion information to get engineering units. I imagine an "insider", as they claim, would have both of these pieces of information in a reasonably succinct form.

I'll await their results.

 

[Anti-sophist]

----
About Me:
MS Electrical Engineering, worked with the USAF (as a civilian) on F15s doing data recording and telemetry. I've designed, built, tested, installed, and maintained flight data acquisition systems, of which the FDR is a very low-bit-rate version. It also has the unique characteristic, among data recorders, of being crash survivable.
-------------

Erm. I forgot to mention my degree is from the University of Florida. I just got the overwhelming sense that this information is appropriate.

I'm not sure why....

 

[apathoid]

Erm. I forgot to mention my degree is from the University of Florida. I just got the overwhelming sense that this information is appropriate.

I'm not sure why....

Jeb Bush is the governor of Florida. Florida miraculously "pulled" ahead of Michigan for the #2 BCS spot. Florida has won the basketball and football national chamionships for 2006. I smell a conspiracy....

eta: Oh and the Buckeyes didnt even get a 100 total yards of offense - they were gotten to...wake up sheeple.

 

[Anti-sophist]

Jeb Bush is the governor of Florida. Florida miraculously "pulled" ahead of Michigan for the #2 BCS spot. Florida has won the basketball and football national chamionships for 2006. I smell a conspiracy....

eta: Oh and the Buckeyes didnt even get a 100 total yards of offense - they were gotten to...wake up sheeple.

Ahem, and the Heat won the NBA title. Marlins and Tampa Bay have also won within the last 4 years.


(And technically Jeb isn't govenror anymore.. but who's counting)

 

[apathoid]

Ahem, and the Heat won the NBA title. Marlins and Tampa Bay have also won within the last 4 years.

See! Its TEH CONSPEERICY!! Its common sense!

(And technically Jeb isn't govenror anymore.. but who's counting)

Oh. Still a good conspiracy theory though.

 

[Anti-sophist]

Silly technicalities like that have never stopped them before. I mean if Marvin Bush is "in charge of security" of the WTC, then Jeb is definitately still governor.

 

[Dog Town]

I'm not sure why....

TGjr, and celebration, six weeks since last game? Great win, atleast it wasn't Spurrier.

 

[Snowygrouch]

FDR data

All,
I have complete data frame layouts for virtually every 757 variant from my source whom I`ve been talking to for several months. I have amassed a great deal of information from her.

The conversion is not yet done, its not an easy process but it will be done. Make no mistake; I have obtained ALL the data nessesary to complely dismember the origional .fdr file which I have in both compressed and uncompressed format.

I will of course share the results (whatever they show) here when that is done. For obvious reasons I cannot provide any further information on where I got the frame layouts or who is doing the computer work.

It was I who origionally got the animation from the NTSB. The animation is not for "illustrative purposes" but is constructed by purpose made software direct from the origional source data with a program such as Insight.

Cant post the address as the server wont let me post a url as I`m a new poster. But the company is Flightscape.

However as has been stated we need to get to the binary data to be absolutely sure about the results.

The heading vector is by digital ring laser gyro accurate to several decimal places; the radio altitude should be accurate to within a few feet.

So we shall see exactly what happened soon enough.
Regards

C.

 

[Firestone]

I know absolutely nothing about how FDRs work.

But common sense )) tells me that the data of the FDR of Flight 77 (found at the Pentagon) will confirm that Flight 77 crashed into the Pentagon.

 

[beachnut]

All,
I have complete data frame layouts for virtually every 757 variant from my source whom I`ve been talking to for several months. I have amassed a great deal of information from her.

The conversion is not yet done, its not an easy process but it will be done. Make no mistake; I have obtained ALL the data nessesary to complely dismember the origional .fdr file which I have in both compressed and uncompressed format.

I will of course share the results (whatever they show) here when that is done. For obvious reasons I cannot provide any further information on where I got the frame layouts or who is doing the computer work.

It was I who origionally got the animation from the NTSB. The animation is not for "illustrative purposes" but is constructed by purpose made software direct from the origional source data with a program such as Insight.

Cant post the address as the server wont let me post a url as I`m a new poster. But the company is Flightscape.

However as has been stated we need to get to the binary data to be absolutely sure about the results.

The heading vector is by digital ring laser gyro accurate to several decimal places; the radio altitude should be accurate to within a few feet.

So we shall see exactly what happened soon enough.
Regards

C.

You have the raw data with the "Parameters Not Working or Unconfirmed" which the NTSB must of run out of money to decode or found it totally superfluous to decode more data from a FDR found in the Pentagon from Flight 77. Are you able to know how many seconds of data never made it to the non-volatile memory? If you can get the raw stuff you should be able to have someone tell you the amount of data in time that was not recorded due to the impact and destruction of 77.

I was looking how 4 second frames are stored; Just knowing where the frames start and end would be interesting. Yet is the final data a complete frame? Is the time stamps from the last frame 2 seconds on the last frame with the last data or the next frame not yet stored?

First of all, it is not important what you find out. I will only sever to prove CT nut cases more wrong.

If you have connections you should be able to explain how much data of flight 77 was lost before being recorded. I need 5 seconds to fit the data into the Pentagon. That is one 4 second frame. There is already enough proof flight 77 did hit the pentagon. Plus the FDR supports what happen on 9/11 when you dovetail it with radar and witness data. I do not like people twisting the data with no facts to support their suppositions.

Unless you have the last data frames you are wasting your time it will still leave the aircraft over 2100 feet away and 300 feet above the impact zone. What do you think?

 

[uk_dave]

I know absolutely nothing about how FDRs work.

But common sense )) tells me that the data of the FDR of Flight 77 (found at the Pentagon) will confirm that Flight 77 crashed into the Pentagon.

Careful now, we're through the looking glass here people.

 

[GlennB]

All,
I have complete data frame layouts for virtually every 757 variant from my source whom I`ve been talking to for several months. I have amassed a great deal of information from her.
....

Welcome Snowygrouch

All anyone here can ask is that you present your findings without prejudice. I'm sure you'll do just that. There are some here experienced in exactly this field and no doubt they'll be more than willing to advise, if necessary.

Regards

Ign ... (oops) ... Glenn

 

[jsiv]

All,
I have complete data frame layouts for virtually every 757 variant from my source whom I`ve been talking to for several months. I have amassed a great deal of information from her.

The conversion is not yet done, its not an easy process but it will be done. Make no mistake; I have obtained ALL the data nessesary to complely dismember the origional .fdr file which I have in both compressed and uncompressed format.

I will of course share the results (whatever they show) here when that is done. For obvious reasons I cannot provide any further information on where I got the frame layouts or who is doing the computer work.

It was I who origionally got the animation from the NTSB. The animation is not for "illustrative purposes" but is constructed by purpose made software direct from the origional source data with a program such as Insight.

Cant post the address as the server wont let me post a url as I`m a new poster. But the company is Flightscape.

However as has been stated we need to get to the binary data to be absolutely sure about the results.

The heading vector is by digital ring laser gyro accurate to several decimal places; the radio altitude should be accurate to within a few feet.

So we shall see exactly what happened soon enough.
Regards

C.

All this stuff about talking back and forth with this "insider" for months and getting closer and closer to cracking it for every day that passes seems a little laughable.

Surely if you have obtained the description of the FDR file format, it shouldn't take very long at all to write a simple program that just dumps all the parameters frame by frame to a text file. I really do not understand why it would be as hard as you try to make it out.

Why don't you just post the "data frame layouts" for the model of recorder that was in AA77 if you have it? I doubt it contains any identifiable information that could get the source in trouble, and it would allowed others to independently verify your claims. It seems like it would speed things up as well.

At the very least tell us more about these "data frame layouts." Exactly what is it you received from this mysterious source?

 

[Anti-sophist]

I'm taking the wait-and-see approach. My hypothesis, for now, is the data will be in accordance with the CSV file, and that will be that.

It seems they are still hung on the heading discrepancy in the animation which has been explained dozens of times as being a magnetic declination problem with the map used in the animation.

I hope that's not where they are pinning their hopes, because it's a dead end.


Anyways, I'll wait and see what information they have, what they post, and what they claim it reveals. Maybe something unexpected will turn up.

 

[Snowygrouch]

Let me clarify a couple of points,
First I`m sorry you feel that the "story with the insider" comes across as laughable. It is what it is..how it appears is superfluous to this investigation.

Second it took months and months because I only GOT the data frames about a week ago.

Third, one week after I spoke to my contact origionally (she HAD agreed to decode the whole file for free before her boss found out which plane it was from) I got a telephone call from the MD of the company which basically said something like:
"can you confirm the flight number of this plane please?..etc etc...in that case we cannot help you with your enquiries goodbye".

My contact ONLY gave me the files on strict condition of absolute anonymity. Her exact words were that her career in the FDR industry would be over if it became industry knowledge that her company tampered with such data. They do work for AAirlines, what do you think would happen to that contract if it became public that they are diddling with AA FDR data for members of the public.....

I`m not for a minuite suggesting its evidence of conspiracy; simply commercial reality in such a niche industry.

Fourth I`m not doing the number crunching so I cannot answer questions relating to the exac procedure followed or the surmountable difficulties we are encountering.

When I`m any the wiser about how many frames we have I`ll post it.

All the engineering units and their accuracies are included in the data frame layout files provided.

As for me "making it out to be harder than it is", well sorry thats because I`m actually trying to do it properly. If it was easy I`d have done it last week. Also if I was so inclined I could just have made up the whole thing and claimed to have done the decode months ago and post any old nonsense. I`m interested in the raw facts of what occured and discussing how easy it OUGHT to be does not accellerate proceedings!

Will I provide the files to anyone else???...

Possibly after we have finished our analysis. Certainly not before.

C.

 

[Anti-sophist]

Yes, the person who gave you those data frames career is at stake. That is unquestioned. I have no problems with keeping your source secret.

That being said, the experiment must be repeatable for it to have any value. That means you will need to release all the data you have. We will dismiss as nonsense any extraordinary findings that we cannot repeat. In order to repeat them, we will need the full data. I urge you to repackage it as best as possible to obfuscate the source.

I also promise that I will repeat any extraordinary findings you happen to come across to verify them. I don't know if you consider that a good or a bad thing.

I've been promised "reports" from "you guys" (pilotsfor911truth, et al.) before and been dissapointed every time. I tend to get the same repackaged nonsense on youtube with newer spookier music. If you plan on actually bringing something new to the table, I'll be excited. Hopefully you can deliver where UnderTow and JDX have failed.

 

[Gravy]

So we shall see exactly what happened soon enough.

Many people already saw what happened, Snowy. On September 11, 2001, to be exact, when flight 77 hit the Pentagon, right in front of them. In the real world.