FDR Expert: No, it’s unlikely that you could skew the flight path or change the altitude or something like that. It would be blindingly obvious if there was a step change going on and you would, there are techniques for smoothing these kinds of things. We do see them but there are techniques we have for smoothing them out because they’re clearly nonsense.

P4T Rep: Ok, so it’d be eliminating erroneous data points basically, uh.

FDR Expert: Yeah, I’m gonna get to that. It’s, uh, and its not a rocket science algorithm we use to do it. It’s fairly straight forward but what it does do is stop step changes and things. (inaudible) And certainly in more modern aircraft where we’ve got more data like, I, I haven’t looked at your data but it’s a 757-200, is that right?

P4T Rep: That’s right, yeah.

FDR Expert: Ok, well a 757-200 will have things like ground speed, air speed, uh, or have wind speed, wind direction. It will have latitude, longitude and what we can do is we can do a gross error check if we know where you took off from and when you consider that we know what the longitude and the lateral and vertical acceleration to be the aircraft is recorded at very high sample rates. So long as you know where you took off from, we can work out exactly where you were and we can then use things like heading, wind speed, ground speed, to correlate that data so that if there was something odd going on for example, if we were suffering for mag-shift, mag-shift is a GPS thing where the ground, um, the Global Positioning System suffers from positional errors we can actually work out the difference, we can work out at where the airplane truly was by pure physics as in it weighs this much, it was traveling at this speed, heading in this direction, and experience these accelerations, up, down, left, and right. We can then look at the GPS data and say here, here is where the mag-shift started at same point and it, mag-shift can be introduced by the flight magnet systems by, um, ground-radio transmitting errors. But at the end of the day, we have some really quite sophisticated tools to work out exactly where the airplane was.

Recent email exchange with a mathmatics and statics expert in reverse engineering data...

QUOTE

Rob,

I posted a little analysis I did based on the FDR data and it suggests that my hypothetical was indeed what was done to the data. I’ve demonstrated it to my satisfaction and I’ll leave the rest in your capable hands. My guess is the simulation was done before the data alteration (that is why in the video it flies north of the Citgo station). To be honest, they really did do a sloppy job in the alteration and I would expect better from our civil servants. The guy who did the work should be fired for not doing a sanity check before releasing it.

911files.info...

I just needed to know if I was dealing with one or two planes before continuing with my own work.

Regards,

John Farmer




QUOTE
From: Pilots For Truth [mailto: pilotsfortruth@yahoo.com ]
Sent: Tuesday, February 27, 2007 10:31 AM
To: John Farmer
Subject: Re: My hypothetical seems to be the case

Hi John,

Are you saying that the .csv file was altered in heading to match the south flight path?

If i understand your work correctly and what you explain above. .this is exactly what you are saying. Give me a call when you get a chance if you can.

Rob



QUOTE

John Farmer wrote:
Yep…

First, let me make it perfectly clear that I am using the NTSB data from the FOIA csv file. I have not altered it in anyway, except to separate components (such as breaking the velocity into horizontal and vertical components). Everything I’m going to cover, others will be able to replicate.

(snip)

What has been done is to take the distance deviation I already discussed and spread it across the horizontal velocity component. In the real world, this equates to longitude. In other words, the longitude data has been “fitted” to hide the angular change in the later part of the flight path. In doing so (for reasons discussed in my prior post) the arrival coordinates changed and since the error was distributed along the entire flight path, the beginning coordinates were also changed (primarily in the horizontal).

The coordinate error could have been easily corrected with a similar correction (introduce an offset). Fortunately, whoever applied the change forgot to do a “sanity check”. Had they done so, I would still be scratching my head.

Hopefully I have made this presentation fairly straightforward. If not, feel free to leave comments below or email me.

Originally posted by johndoex
We did notice the animation flight path right away. But we did not report it (right away) and instead worked on altitude because we thought the same as you when we saw the heading. We had thought the NTSB messed up in their plot and rotated the map slightly. However, when Aldo and Craig (CIT) notified us of the witness(es) they had which confirmed the animation plot north of Citgo, we added the flight path to the rest of the questions for the NTSB which can be found here - pilotsfor911truth.org... - scroll down.

Then we also made a flight path video - also can be found on above page.