The accident occurred on 12 November 2001, when the A300's vertical fin broke away as flight AA587 climbed out of New York Kennedy airport.
Investigators found that the pilot commanded a series of five heavy rudder inputs, alternately deflecting the rudder in one direction then the other, intending to counter a roll disturbance induced by wake turbulence. These rudder reversals exerted excessive loads on the fin and it sheared off.
While the sequential rudder inputs were "unexpected" and "non-conventional", the European Aviation Safety Agency said, the results of a pilot survey published at the end of 2010 indicated that the rudder "is still reported to be used or considered for use by pilots in ways they have not been trained".
It added that the actions "sometimes contradict" industry guidance on aircraft upset recovery.
EASA has approved a design change involving installation of a "stop rudder inputs" warning system, and is proposing to order A300-600 and A310 operators to fit the device within four years.
The equipment monitors rudder inputs and triggers both aural and visual warnings if it detects a single "dangerous" rudder doublet.
EASA said it is still co-operating with the US Federal Aviation Administration to determine whether, and to what extent, certification standards for large transport aircraft can be amended to take into account possible excessive use of the rudder.
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