The co-pilot of American Airlines Flight 587 (search) caused the November 2001 crash that claimed the lives of 265 people, the staff of the nation's airline safety agency reported Tuesday.

Investigator Robert Benzon of the National Transportation Safety Board (search) staff said the copilot's response to turbulence, just seconds after the Airbus A300-600 (search) plane took off from New York's John F. Kennedy International Airport (search), was "unnecessary and aggressive."

Benzon also said that investigators found that American Airlines improperly trained its pilots to use the aircraft's rudder while recovering from upsets and said the problem could have been exacerbated by the airline's simulator training.

Benzon also said that the rudder control system on the aircraft is sensitive at higher air speeds, which is potentially hazardous.

The safety board itself was expected to rule later Tuesday on the staff's findings.

On Nov. 12, 2001, First Officer Sten Molin (search), the co-pilot, moved the plane's rudder back and forth after takeoff, trying to control the climbing aircraft, not realizing he was sealing the grim fate of those on board.

Molin was at the controls when the plane hit turbulence almost immediately after taking off for the Dominican Republic.

"Hang onto it, hang onto it," Capt. Edward States implored.

"Let's go for power, please," Molin said.

A second later came a loud bang, which investigators believe was the tail breaking off. Then came the roar of air rushing against the aircraft and alarms sounding in the cockpit.

"What the hell are we into (inaudible)?" Molin said. "We're stuck in it."

States' last recorded words came five seconds later: "Get out of it! Get out of it!"

Both Airbus Industrie (search), which manufactured the jetliner, and American Airlines, which trained Molin, agree that if he had taken his foot off the rudder pedal, the tail wouldn't have broken off, the plane wouldn't have plunged into a New York City neighborhood. It was the second deadliest plane crash on U.S. soil.

But Molin didn't know he was putting more pressure on the tail than it could bear. Why he didn't — and who's to blame for that — is the subject of a bitter fight between Airbus and American.

According to investigators, Molin tried to steady the aircraft using pedals that control the rudder, a large flap on a plane's tail. When his initial movement failed, Molin tried again and again. His actions placed enormous stress on the tail.

American, the only U.S. airline to use that type of Airbus plane for passenger service, claims Airbus didn't alert it to the danger of sharp rudder movements until after the crash. The airline also contends the Airbus A300-600 has uniquely sensitive flight controls that can cause more severe rudder movements than the pilot intends.

"Airbus had the ability to truly red-flag the issue," American spokesman Bruce Hicks said.

Airbus says it told American a number of times and in a number of ways that the airline was improperly training pilots about how to use the rudder.

An Airbus spokesman declined to comment on the investigation before the hearing. However, the company has provided the NTSB with a number of documents to support its claim.

For example, a letter dated Aug. 20, 1997, warned American chief pilot Cecil Ewing that rudders should not be moved abruptly to right a jetliner or when a plane is flown at a sharp angle. The letter was signed by representatives from The Boeing Co., the Federal Aviation Administration and Airbus.

Airbus contends that even people within American Airlines were concerned about how the airline was training its pilots. A letter to Airbus dated May 22, 1997, from American technical pilot David Tribout expressed concern about the airline's then-new training course on advanced maneuvers.

"I am very concerned that one aspect of the course is inaccurate and potentially hazardous," Tribout wrote. His concern: Pilots were being taught that the rudder should be used to control a plane's rolling motion. Hicks countered that Airbus didn't share important safety information about the rudder after a problem with American Airlines Flight 903 (search) in May 1997. During that incident, pilots used the rudder to steady an Airbus A300-600 plane on approach to West Palm Beach airport. The plane nearly crashed and one person was seriously injured.

Afterward, Airbus told the NTSB that it included a warning that abrupt rudder movement in some circumstances "can lead to rapid loss of controlled flight," and, in others, could break off the tail.

Hicks said Airbus' comments didn't specifically say the rudder movements on Flight 903 had exposed the tail to so much pressure that it could have been ripped off.

Immediately after the Flight 903 incident, an inspection found no damage to the tail. But five years later, the plane was inspected more closely because of concerns aroused by the crash of Flight 587. Cracks were found and the tail was replaced.

John David, a spokesman for American Airlines' pilots union, said pilots had always thought that they could use rudders to the full extent without hurting the airplane. He also believes Airbus didn't properly communicate what it knew.

American now gives its pilots specialized training on the rudder control system based on information learned during the investigation.