Moments after takeoff from John F. Kennedy International Airport, an American Airlines pilot pressed hard on rudder pedals to help stabilize the shaking plane from wake turbulence. But instead of smoothing the ride, the National Transportation Safety Board said yesterday, the pilot's action was "unnecessary and too aggressive" and resulted in the plane's tail falling off. Seconds later, the plane plunged into a New York neighborhood, killing 260 people onboard and five on the ground.

The safety board said the pilot, Sten Molin, had a history of overreacting to wake turbulence and was trained by American to use the movable flap on the plane's vertical tail to help stabilize the plane if it unexpectedly rolled in flight. The Airbus A300-600's sensitive rudder-pedal design and American's "negative" pilot training contributed to the Nov. 12, 2001, crash, the safety board concluded.

The official findings put to rest earlier concerns that the crash was caused by a terrorist act or faulty design of the plane's tail. It was the first U.S. crash involving an aircraft built by Airbus SAS, the world's largest manufacturer of commercial planes, and the first accident in which a major section made of composite material broke off from a plane during flight.

"It's not only a lesson for American, it's a lesson for all pilots, and it's a tragic lesson, unfortunately," NTSB Chairman Ellen Engleman Connors said.

As a result of the crash, the NTSB recommended that the Federal Aviation Administration require manufacturers and aviation operators to provide better pilot training on rudder capabilities and proper rudder use in flight. It also recommended the FAA review the rudder design of Airbus A300-600 and the similar rudder on A310 aircraft. The board did not say that the Airbus planes are dangerous; rather, it said that in certain conditions, the planes' rudder system is too sensitive.

American is the only commercial passenger carrier to fly the A300-600 in the United States, and no domestic passenger carriers fly the A310. There are about 500 of both Airbus models, the company said.

Investigators said the pilot, who was experienced with the aircraft, had been known to overreact aggressively to wake turbulence. One pilot who flew with him said he used the rudder too aggressively when the plane experienced moderate bumps, and that Molin explained he was doing as he had been trained by American.

Molin had attended American's advanced training program, which sought to teach pilots how to better recover after an unexpected, dangerous incident. In one scenario similar to the Flight 587 accident, American's training video prompted pilots to respond to dramatic wake turbulence after following a 747 into the sky. Flight 587 encountered wake turbulence from a preceding 747 flown by Japan Airlines, investigators found.

American's simulation taught pilots to use the rudder, which controls the vertical tail's back-and-forth movements, along with the wings to stabilize the plane.

But the safety board said the training was inaccurate because it taught pilots to associate wake turbulence with using the rudder, which the board found unnecessary. Investigators said the pilot's back-and-forth movements of the rudder pedals made the situation worse. Had Molin done nothing, Flight 587 would not have crashed as it lifted off for the Dominican Republic.

"He incorrectly perceived these reactions [of the aircraft] as caused by outside turbulence rather than his own actions," said Malcolm Brenner, an NTSB investigator. If the pilot had stopped pushing on the rudder pedals, "the accident would not have occurred."

American said it has adjusted its pilot training to reflect concerns raised by the accident. The airline said it still believes that the aircraft's rudder, not the training program, was to blame.

"That was a generally accepted belief: that you could use all the controls available" within normal operation of the flight and not break the aircraft, said Bob Reding, American's senior vice president of technical operations. "We need clear guidance to make clear the limitations of the rudder."

The safety board also concluded that the Airbus rudder was more sensitive than those on comparable aircraft and that its performance differed dramatically on the ground, in the air and at high speeds. Airbus said it would work with the FAA if the agency decides to review its rudder design.

The "tragic coupling of both the pilot and the aircraft really was the precipitating event that took down Flight 587," NTSB Vice Chairman Mark V. Rosenker said.

The board voted to discuss developing more formal standards to have the FAA receive reports of overseas safety incidents that might help prevent similar incidents in the United States.

The issue arose after investigators said they were "disappointed" that Airbus and American were less than forthcoming in providing information about the rudder performance of another A300-600 involved in a non-fatal accident four years before Flight 587 crashed.

American alleged that Airbus withheld information about its rudder system in the 1997 incident, in which the plane stalled and its rudder was damaged; pilots regained control of that plane. The safety board ruled that incident was unrelated to the rudder-design issues raised by Flight 587.

But the board said it will address urging the FAA to develop a formal program to share information with other nations' safety agencies. "Unless everyone is forthcoming, it does hinder, and many times prevents us from doing the right thing at a much earlier stage," Rosenker said.

Olivia Ortiz, left, and Ana Zabala, relatives of victims of American Airlines Flight 587, listen to proceedings of an NTSB meeting on the Airbus A300-600 crash, which left 265 people dead.