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Computer-Related Incidents with Commercial Aircraft

American Airlines Flight 587, A300-B4, In-Flight Break-up, New York, November 2001

12 November 2001

Synopsis Shortly after takeoff from New York's John F. Kennedy airport, American Airlines Flight 587 lost its vertical stabiliser and crashed out-of-control into a neighborhood of Queens, NY. The accident generated much press coverage and much speculation about whether the composite vertical stabiliser, which broke off at its root, is a comparably adequate piece of engineering to the traditional metal-alloy stabilisers it replaced. There was controversy also about whether the pilot flying, the first officer, had used inappropriate technique to control the aircraft through a wake turbulence encounter, or whether the supremely high sideways loading of the stabiliser (some 1.9 times design load) had been caused by an as-yet-unidentified control anomaly, perhaps related to the yaw damper. Finally, the manufacturer Airbus, as well as Boeing and the FAA, had previously written American Airlines expressing concern about how AA taught the use of rudder in recovering from flight upsets, and whether that would result in extreme loading of the tail. American Airlines had claimed that they did not teach use of rudder in that fashion; and then came the accident, as if foreseen.

Upon release of the final report, the Chairman of the NTSB complained publically about the lobbying from both Airbus and American Airlines, which she said had hindered the investigation because they mostly repeated themselves rather than contributing new information to the investigation.

There are a lot of opinions still around about the accident: whether the first officer just did what came naturally and a bad rudder-control design led to the high, deadly, tail loadings; whether the first officer just had poor, dangerous technique and no one relieved him of it; whether American Airlines taught use of rudder in such circumstances and the first officer followed his training; whether composite fins are less appropriate to their task than metal-alloy fins.

I wrote a guide to the engineering issues, The Crash of AA587: A Guide, which was well received by people whose opinion I value, including one principal in the engineering investigation. I recommend it to those who are having trouble sorting out data from noise.

The report and the docket materials are available on the U.S. NTSB WWW site at www.ntsb.gov/events/2001/AA587/default.htm

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