FDR Redux?


A Flight 800 crash investigator has told the Voice that TWA recently challenged the National Transportation Safety Board’s interpretation of the last complete line of data taken from the plane’s Flight Data Recorder (FDR), saying that the software used to analyze the data is outdated and unreliable. The 747 went down off Long Island on July 17, 1996, killing all 230 people aboard. The NTSB says the crash was caused by an explosion in the plane’s center fuel tank, but has been unable to identify the source of the spark that ignited the explosion.

The NTSB published its findings late last year, in a report written by Flight Data Recorder Group chairman Dennis Grossi. But the questions raised by TWA prompted Grossi to invite a TWA engineer to visit the NTSB’s lab in Washington to review the raw data as it was retrieved from the FDR’s magnetic tape. That meeting was set for last week. If TWA remains unconvinced that the NTSB position is correct, the investigator said, the NTSB may call the entire FDR Group back to Washington. In that case, group members (including representatives from TWA, Boeing, the Air Line Pilots Association—and in this case, the FBI too) will get another shot at explaining what the information on the FDR tape means.

At issue is the significance of the last line of data, which contains several values that pilots say are impossible for a 747 in flight to generate. The NTSB says these values are garbled and useless data left over from a previous flight. But retired Navy commander William S. Donaldson insisted at a Washington press conference in January and again on July 20 that the last line of FDR data is indeed from Flight 800 and that the values recorded are evidence of the explosion of a missile warhead outside the airplane. (See Voice, July 21.)

TWA spokesman Mark Abels declined to comment. Peter Goelz, managing director of the NTSB, did not return a call seeking comment.