program decompresses the raw Flight Data Recorder (FDR
commonly called "black box")
file for American Airlines Flight 77 (AAL77) included by the US
Transport Safety Board (NTSB) on CDROMs provided in response to FOIA
(Freedom of Information Act) requests for information regarding the
events of September 11th 2001.
One subframe is written per line. The 12-bit words are written in
binary with a space in between them starting from word 1 and continuing
through to word 256.
The end of a compressed section of data is marked by the line Sync
Lost. The last frame before Sync Lost will be incomplete, so the last
subframe before Sync Lost will most likely have fewer than 256 words.
can download the output file generated by the program from here.
To decode the 12-bit words
you can use the data frame layouts from here
The subframe number of a frame can be calculated by treating the first
(most significant) two bits of word 1 as a 2-bit unsigned integer and
Alternatively I have also written an AAL77 FDR Decoder
In the interests of transparency in showing that the program is really
generating its output from the raw FDR file, you can download the C# source code
used Microsoft Visual C# 2008 Express Edition to create it. You can
look at the .cs
source files using any text editor, and you can download the
Visual C# 2008 Express Edition from Microsoft
it. Alternatively, you may be able to get a DVD with the Visual Studio
Express Editions from your local Microsoft sales office.
As I am providing this program free
of charge, it is provided as is.
I take no responsibility for what the program does or doesn't do.
However, you can email
feedback to me (Warren Stutt).
You will need to download a copy of the FDR file American
you want to run the
can download a copy from here.
You can also
get an ISO image of the entire CDROM that
I received in response to my FOIA request which
includes the FDR file from here.
A Change Log detailing the
changes in different versions is available here
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