ROSE Bug Report Letter to the NTSB
Dated 24th October
I previously thought that the reason why my
AAL77 FDR Decoder decodes
almost 4 seconds more data from the raw Flight Data Recorder (FDR
commonly called "black box") file for American Airlines Flight 77
(AAL77) than appears in the Comma
Separated Value (CSV) file produced by the United States National
Transportation Safety Board (NTSB) for that flight was that the
software they used did not decode incomplete frames from the end of
I have obtained a decompressed file produced by version 3.6a of ROSE
from the raw FDR file for AAL77. The ROSE software is produced by the
L3 Communications Aviation Recorders division for the purpose of
reading data from the FDRs that they supply. I found that the
decompressed file includes incomplete frames from the end of the
flights prior to the final flight. However there are differences
between my decode and the decompressed file at the end of the final
flight. I now believe that this is due to a bug in that version of the
I reported my findings to the L3 Communications Aviation Recorders
division. They replied that version 3.6a was not the latest version of
the ROSE software. Unfortunately, they also said that they were not
willing to investigate my findings further, but would do so at the
request of an accident investigation office.
On 25th October 2010, I posted the
following letter to the NTSB. An ISO image of the CDROM that I included
with that letter is available here.
Details of my
FOIA request that I
referred to are available here.
I will provide an update when I receive a response.
I have sent another
letter to the NTSB regarding my further findings.
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