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 The Safety Board is concerned that AC 20-141 was not finalized until more than 8 years after the issuance of Safety Recommendations A-91-23 and -24. Nonetheless, the Board is pleased that the AC is now final and that it will provide airlines with critical and necessary guidance to properly document FDR parameters and systems. As a result, information from FDRs will be provided in the format needed by the Board for a complete and accurate readout.

In addition to AC 20-141, ICAO Annex 6, Part I, "International Commercial Air Transport--Aeroplanes," includes Attachment D, Flight Recorders. Section 3 of the attachment, entitled "Inspections of flight data and cockpit voice recorder systems," provides guidance to Member States on the continued airworthiness of FDR systems, such as details on how to conduct annual checks of every FDR parameter, including recorded signal and transcribed engineering units. Paragraph 3.2.c states that "a complete flight from the FDR should be examined in engineering units to evaluate the validity of all recorded parameters." In addition, paragraph 3.2.d states "the readout facility should have the necessary software to accurately convert the recorded values to engineering units and to determine the status of discrete signals." If Korean Air had been following this ICAO guidance and performing annual checks on all of the FDR parameters for the accident airplane, the airline would have been able to determine the conversion equations necessary to complete an FDR readout or would have been able to discover and correct the FDR parameter documentation discrepancies.

As the number of international flights increases, the possibility of accidents involving foreign aircraft within the United States also increases. The Safety Board concludes that it is critical that thorough documentation of the information recorded by an FDR be available for foreign- or U.S.-registered air transport airplanes that fly into or out of the United States. In accordance with the interagency group on international aviation protocol, the Board will introduce AC 20-141 at the next ICAO flight recorder panel meeting, with a proposal that the AC be adopted as the international standard and recommended practice for FDR systems.