Need debunk for Pentagon FDR. Thanks.

alexg

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Would someone care to debunk this for me, or point me to a thread that does? It's from a debate in another forum. I have yet to hear how the FDR data is resolved. Thanks.


http://pilotsfor911truth.org/pentagon.html

We have determined based on the Flight Data Recorder information that has been analyzed thus far provided by the NTSB, that it is impossible for this aircraft to have struck down the light poles.

We have an animation of the entire flight provided by the NTSB. I have sat through the whole flight from taxi out at Dulles... to the impact at the Pentagon in real time.

The screenshot below shows the very last frame of the recorded data. Its stops at 9:37:44 AM EDT (Official Impact Time is 09:37:45). You will notice in the right margin the altitude of the aircraft on the middle instrument. It shows 180 feet. This altitude has been determined to reflect Pressure altitude as set by 29.92 inHg on the Altimeter. The actual local pressure for DCA at impact time was 30.22 inHg. The error for this discrepancy is 300 feet. Meaning, the actual aircraft altitude was 300 feet higher than indicated at that moment in time. Which means aircraft altitude was 480 feet above sea level (MSL, 75 foot margin for error according to Federal Aviation Regulations). You can clearly see the highway in the below screenshot directly under the aircraft. The elevation for that highway is ~40 feet according to Google Earth. The light poles would have had to been 440 feet tall (+/- 75 feet) for this aircraft to bring them down. Which you can clearly see in the below picture, the aircraft is too high, even for the official released video of the 5 frames where you see something cross the Pentagon Lawn at level attitude. The 5 frames of video captured by the parking gate cam is in direct conflict with the Aircraft Flight Data Recorder information released by the NTSB. More information will be forthcoming as we come to our conclusions on each issue. We have contacted the NTSB regarding the conflict between the official story and the FDR. They refuse to comment.
 
The best beat-down of John Doe X's miscalculations occurs in this thread. Poster Anti-Sophist shows that John Doe X's assumption that the aircraft was travelling in a straight line is not only wrong, but to blame for his incorrect conclusions.

Also in this post I raise additional sources of error, here Skeptic4Sure passes along JDX's response (unless Skeptic4Sure is JDX), and here I show his response to be completely unsatisfactory. They haven't been heard from since.
 
I have actually studied the flight-data recorder in quite a bit more detail, and am preparing a longer version. That particular mathematical analysis deals with one particular set of numbers (altimeter), and ignores the rest of the FDR.

JDX combines FDR information willy-nilly without ever proving it's internally consistent. For instance, a likely objection to my "work" is that the final moments G-meter don't indicate a positive acceleration, but it's fairly trivial for me to show that the two columns aren't correleated in time very well.

I'm still working.


The fundamental problem, as always, is false precision. Error is completely unaccounted for, and all of the data is treated as infinitely precise. Once you correctly account for error, everything can be handled. This includes instrumentation error, and time-lag error.

Furthermore, I worked for a year for the USAF doing instrumentation and data collection on F15s, and as such I understand the basics of PCM data. I have my doubts that the CSV file floating around is really the "raw" data, given my background with aircraft data collection and instrumentation, the CSV file appears to have undergone some level of preprocessing... This preprocessing appears to have removed some very important information required to remove the amount of error required to do this calculation precisely. I'll detail it more once I have the facts straight on the actual electronics of the FDR.

This reminds me, does anyone know whether any data-sheet or even model of the actual FDR used in Flight 77?
 
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Also, if you don't mind, post or pm me a link so I can read what people are saying. Unlike certain folks, I am more than happy to entertain criticism and fix apparent flaws.
 
Hi All,

Here are some things I found interesting on their forum.

At 09:37:42 The Flight Data Recorder was descending at 5520 fpm. The Flight Data Recorder shows .7 G's being pulled between :42 and :43 (1.7 G's total, 1 G is normal gravity and is the zero point). At 09:37:43 the descent rate had slowed by 1440 fpm to 4080 fpm. 1440 fpm is 24 ft/sec. 32 ft/sec^2 is acceleration due to gravity. 24/32=.75. The FDR cross checks with the math.

The FDR shows the aircraft pulling 1.7 G's at top force to slow the descent rate by 1440 fpm.

At :44 the descent rate was 3980 fpm. The average G's pulled between :43-:44 was 1.04 G's. The FDR shows .04 G's needed to slow descent rate by 100 fpm. Makes sense.

From the :44 time stamp to impact time of :45, the average G's were .66 G's. .66x32ft/sec^2=21ft/sec increase in vertical speed. 21ft/secx60=1267 fpm increase in descent rate from :44-:45 official impact time.

3980 as shown at :44 plus 1267 fpm increase in descent rate = 5247 fpm descent rate for the last second :44-:45 data.

Conclusion - This descent rate is impossible to have been accomplished if the aircraft was low enough to hit the poles. It would have dug itself into the ground long before getting to the pentagon. 5247fpm is also not enough to have hit the pentagon from the altitude recorded by the Flight Data Recorder.
Click to expand...

Using a more accurate descent rate based on G Force.

Official Impact time of 09:37:45.
Speed used - 784ft/sec
Descent rate = 5247 fpm = 87.5 ft/sec. (based on G Force recorded between :44-:45)

Pole 1 distance from impact hole = 1012 feet/784 = 1.30 seconds
Pole 2 = 886 feet/784 = 1.13 seconds
Pole 3 = 708 feet/784 = .90 seconds
Pole 4 = 598 feet/784 = .76 seconds
Pole 5 = 467 feet/784 = .60 seconds

Pole 1 height in MSL = 74.5 MSL
Pole 1 aircraft height = 87.5(1.3 seconds)+10.38 impact hole height + 38' MSL at pentagon = 162.13 MSL at pole 1
Aircraft was 87.63 feet above Pole 1

Pole 2 = 83' MSL pole height
Pole 2 aircraft height = 87.5(1.13)+48.38= 147.25MSL
Aircraft was 64.25 above Pole 2

Pole 3 = 82'MSL
Pole 3 Aircraft height = 87.5(.90)+48.38 = 127.13'MSL
Aircraft was 45.13' above Pole 3

Pole 4 = 82'MSL
Pole 4 Aircraft Height = 87.5(.76)+48.38 = 114.5'MSL
Aircraft was 32.5 feet above Pole 4

Pole 5 = 81' MSL
Pole 5 Aircraft Height = 87.5(.60)+48.38 = 100.88'MSL
Aircraft was 19.88' above Pole 5


As a reminder, this analysis is a hypothetical based on working back from the impact hole with new G Force analysis added for a more accurate descent rate between :44-:45 time stamps. For a more accurate aircraft altitude in terms of MSL indicated by the altimeter and corrected for local pressure, please visit pilotsfor911truth.org pentagon page.. mid page.
Click to expand...


Errors.

Although most pilots already know this...

All Airdata systems go through rigorous testing to remove errors at various speed, angles of attack, and position error. The following are highlights to show how an airdata system is calibrated to remove errors when undergoing certification. Full report is linked below.

"The presence of the aircraft in the airstream causes input errors to the measuring
instruments — the aircraft disturbs the air that it flies through, thereby also disturbing the airdata
measurements. Figure 1 shows the airflow around an airplane wing."


"Accurate airdata are necessary for many purposes and applications. Obviously, the pilot
cannot safely fly the aircraft without knowing airspeed and pressure altitude. In civil aviation, the
small vertical separation between flight levels assigned by air traffic controllers is based on
accurate knowledge of pressure altitude."


"Static pressure can be measured with a pitot-static tube or a flush-mounted port on the
fuselage. Figure 3 shows a typical subsonic static pressure distribution on an aircraft fuselage
(ref. 2). The measured minus true static pressure, , normalized to compressible dynamic
pressure, , is plotted as a function of fuselage position. Zero static pressure error on the
fuselage exists at locations 2 through 5."

"Even with the selection of the best static port position, some pressure errors will remain, and
these errors must be determined in flight. The difference between the locally measured static
pressure and the ambient static pressure, which is dependent upon angle of attack, airspeed, and
aircraft configuration, is called
position error.
.
Three calibration types are generally used to determine position error: direct comparison,altimetry, and velocimetry."

"This subsection describes typical maneuvers and methods for most airdata calibrations.
Tower-flyby, trailing static or trailing cone, pacer aircraft, radar tracking, and dynamic maneuvers
are included."

"Lag and attenuation can be estimated or measured experimentally. Criteria can be set for how
quickly pressure can change in the pneumatic system without affecting the airdata. Such
calibration methods as the trailing cone may have very large pneumatic lags and may have to be
used in steady flight."

"Airdata quantities are needed for a multitude of tasks, including flight safety, control,
navigation, weapons delivery, flight test, and flight research. These quantities generally need to
be measured and then calibrated to remove errors. The techniques and procedures have been only
briefly described here; numerous references should be studied if airdata values are to be measured and calibrated."

http://dtrs.dfrc.nasa.gov/archive/00000221/01/104316.pdf

Conclusion - The Flight Data Recorder doesnt have any errors in terms of air data (altitude, airspeed). Those errors are removed during calibration testing for certification.
Click to expand...
 
Dog Town said:
We were just victims of a JDX drive by!
Click to expand...


Haha, You think I'm JDX? How many other "JDX's" do you have over here? I bet anyone who quotes their forum must be "JDX".

I haven't read the other threads I was posting on over here, but I'm sure some people probably think I'm JDX.

I haven't had much time to play online, but I thought I would drop by and see what was new. I came across this thread and posted some quotes I read the other day. Do with it what you will.
 
This quote says it all by Anti-Sophist.

There are a few other explainations, as well, but yours sounds plausible. I'm not an expert on how to interpret this data, but simple things can effect G-forces.
Click to expand...
 
weedwacker said:
I briefly looked over there. It doesn't account for the less than 1 G after :44-:45.

It looks like JDX has accounted for the 1.7 G pull in the 1440 fpm decrease in decent rate.

Anti-So says we needed 3 G's to pull out of that dive. 3 G's is no where to be found on the FDR data.
Click to expand...
yawn - Why don't you actually present the quotes and address them in an intelligent manner rather then this, pilotboy.
 
JDX is mixing data on the flight recorder assuming all of it that has the time-stamp actually occured at the same time. There are a million and one reasons to conclude that the RECORDED time is not the same as the MEASURED time.

There is AMPLE evidence of this, in the data itself. I will provide more details as the time goes.

You need to, before combining multiple sources of data, correct for time shifts.

Furthermore, there is evidence that this data comes from a fixed-frequency PCM stream, and, in the form the data is presented, does not translate into a fixed-frequency PCM stream. In other words, somewhere along in the processing or preprocessing of this data, time-information has been lost.
 
weedwacker said:
Hi All,

Here are some things I found interesting on their forum.
Click to expand...
Yep, quite interesting just how wrong they all are...

Conclusion - This descent rate is impossible to have been accomplished if the aircraft was low enough to hit the poles. It would have dug itself into the ground long before getting to the pentagon. 5247fpm is also not enough to have hit the pentagon from the altitude recorded by the Flight Data Recorder.
Click to expand...
Conclusion is wrong. See Anti-Sophist's chart showing height vs. distance downrange.

The calculation is showing how much the rate of descent fluctuated in the last three seconds before the end of the recording. It clearly shows just how rapidly the aircraft could adjust its trajectory. Yet here John Doe X (I presume) is saying (a) it was too high to hit the Pentagon with "that rate of descent" and (b) it would have been too low had it hit the poles.

Ridiculous. You can't extract a three second record and use that to bound the entire flight path. The aircraft had way more performance than that, and what we see in the last three seconds is absolutely 100% consistent with last-second corrections on a high-speed collision course. The author is either attempting to deceive, or gifted with an uncommon immunity to logical thought.

Using a more accurate descent rate based on G Force.

Official Impact time of 09:37:45.
Speed used - 784ft/sec
Descent rate = 5247 fpm = 87.5 ft/sec. (based on G Force recorded between :44-:45)
Click to expand...
"More Accurate" indeed. Now he takes a single second out of the FDR, uses that to assume an even steeper straight line descent -- but still insists on a straight line -- and surprise! the flight plan doesn't match up.

Why would anyone make not one, but two such absurd assumptions?

Conclusion - The Flight Data Recorder doesnt have any errors in terms of air data (altitude, airspeed). Those errors are removed during calibration testing for certification.
Click to expand...
The conclusion is totally wrong. We've already read that paper, which was produced by NASA Dryden, sister center to where I work, and it shows that there are sources of error. It gives ways to compensate for them. Ways, verily, that John Doe X does not understand and does not use in his derivation.

So yes, quite interesting. It gives a rare glimpse into just how technically ignorant they are over there. And how desperate to defend their already laughable theory that Flight 77 somehow missed the Pentagon, and that throngs and throngs of people participated in this grand coverup, enough to fool everyone in the world except Mr. John Doe X -- a true patriot who, despite his inability to calculate a simple parabola or propagate errors, is the only one gifted enough to expose the FDR data for what it truly is: A falsification, almost perfect, but with "subtle flaws" deliberately left in, a final mocking touch of the NWO supervillains, the telltale signature... of the Twilight Zone.
 
TheGrunion said:
Are you going to answer my questions Weedwacker?
Click to expand...


I'm still researching. But JDX's work is starting to make sense, although it doesn't make sense with the official story. I have contacted a few people I know and we are still working on it. I have a feeling the FDR might be a fake. That is the only way I can explain it right now. If it is a fake, the NTSB has a real problem releasing fake data through the FOIA.
 
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