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Old 5th February 2011, 04:47 PM   #4292
wstutt
Thinker
 
Join Date: Sep 2006
Location: Brisbane, Australia
Posts: 132
Hi Senenmut,

Originally Posted by Senenmut View Post
wstutt-
i wonder if you have any more information regarding these two "data fields" that dennis cimino speaks of. i asked farmer but he just defered it to the ntsb. would someone have to go into the "raw file" to zero these out?

<snip>
I did find that information within the flight data, not in the preamble. Here is what I wrote about it at PFT in response to Dennis Cimino:
Originally Posted by wstutt on the PFT forum
Hi Dennis Cimino,

I have now decoded the FLEET IDENT and A/C NUMBER parameters from the FDR data according to the generic Boeing data frame layout 757-3B. When they are interpreted as unsigned integers they have values of 1 and 35 respectively. Although they were not in the text preamble of the file where you were expecting to find them, do you think they could be used to identify the aircraft? They do not appear to me to be a tail number, however if I understand you correctly, you were not expecting them to be a tail number.

<snip>
The two fields are not zeroed out in the plain text preamble. They do not appear at all.

It would be possible for someone to remove them from the preamble by modifying the FDR file, but I have no evidence that anyone did this.

I have four FDR files from another source and they also have no AC ID or FLEET ID fields. Rob Balsamo asked me to share the other files, but my source has has denied permission since they were from a client and that client had not given permission for my source to share the files with me. My source shared the files with me so that I could help him decode them.

I think that the AC ID and FLEET ID fields never appear in the text preamble contrary to Dennis Cimino's claim that they always do.

Warren.
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