ROSE Bug Report Letter to the NTSB Dated 24th October 2010

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 flights.

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 ROSE software.

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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