Safety board publishes study of 2001 American Airlines accident, laying most of blame on Airbus rudder design
The simmering controversy over the 12 November 2001 American Airlines 587 crash has reached boiling point following the US National Transportation Safety Board's (NTSB) publication of scientific studies of the event. On balance, these appear to load most of the blame on Airbus for designing a rudder system that was exceptionally sensitive, so that pilot rudder inputs caused the Airbus A300-600R's tail fin to separate during climb-out from New York's Kennedy airport, resulting in the crash that killed all 260 people on board.
These studies are part of the ongoing NTSB investigation into the accident at Belle Harbour, New York. The agency contracted Dr Ronald Hess, professor and vice-chairman of the department of Mechanical and Aeronautical Engineering at the University of California, to examine previous examples of pilot-induced oscillation (PIO) - established to have taken place just before the AA587 fin separation - as well as the evidence from the accident itself. Hess's report says that although PIO is, by definition, started by pilot action and reaction, "the sensitivity of the rudder control system of the A300-600R could constitute a control system characteristic conducive to a PIO". The NTSB, taking up this point, says that therefore, while "overcontrol by the pilot flying might be cited as a factor...it is erroneous to attribute these inputs as a cause rather than an effect".
Airbus has countered with its own analysis, pointing out that the studies do not question the fact that the aircraft performed in every way it was certificated to do, including the fin strength. It blames American Airlines for the way it carries out its pilot upset recovery training programme. Airbus alleges that American's "advanced aircraft manoeuvring programme" (AAMP) encourages dangerously heavy use of the rudder, considering the limitations of large aircraft. Airbus says: "There have been four events involving high lateral loads reported since A300-600 entry into service, and they all involved the same operator, American Airlines."
American, angry at the implications that could be drawn from NTSB warnings published after the accident about rudder use in large aircraft, says NTSB-commissioned studies exonerate its AAMP training as irrelevant to the accident.
DAVID LEARMOUNT / LONDON & GRAHAM WARWICK / WASHINGTON DC
Source: Flight International
