2004-05-21 / Front Page

Expert: AA 587 Pilot ‘Shocked’ By Forces On Rudder

By Howard Schwach

Expert: AA 587 Pilot ‘Shocked’ By Forces On Rudder

By Howard Schwach

A computer systems professional who has become an expert on the crash of American Airlines Flight 587 has told The Wave that, after studying submissions to the National Transportation Safety Board (NTSB) from the airlines, the plane’s manufacturer and the pilot’s union that he is sure that Sten Molin, the first officer who was flying the Airbus A-300, was "shocked by the lateral forces produced by the first rudder movement after the plane hit wake turbulence from a Japan Airlines Heavy that took off just prior to its own takeoff.

"I read all of the reports carefully," says Vic Trombettas, "and for all of their disagreements, they all agreed on one thing: that the pilot was shocked by the lateral forces produced by the first rudder movement."

"Of course," Trombettas points out, "one side blames the sensitivity of the rudder system [for the crash] while the other side blames the AA training system for over-emphasizing rudder use for roll control."

Trombettas thinks that the final NTSB report on the crash, which will be released this summer in Washington, D.C., will say that the pilot left the American Airlines training program with the impression that the rudder should be used for the most reliable roll control authority in wake upsets [incidents in which wake turbulence is experienced in control situations].

According to Trombettas, "The pilot was therefore aggressive with the rudder in responding to what he thought was a wake encounter when he was in a 25 degree controlled left turn. In all likelihood, the pilot feared that the wake encounter might roll his aircraft well beyond the 25 degrees."

He adds, "The pilot was in all likelihood not aware of the limited pedal travel at 250 knots which would provide him with full, available rudder travel... The pilot quickly got caught in an APC/PIO [Aircraft Pilot Coupling/ Pilot Induced Oscillations] event given that he was not aware that small rudder pedal movements could produce strong yaw forces."

Trombettas blames a number of contributing factors for the pilot’s inability to control the Airbus jetliner.

• -The failure of Airbus to communicate the redesign of the rudder system to the airlines that flew the plane.

• -The American Airline training program, which, coupled with the sensitive rudder, "created a dangerous mix."

• -The failure of Airbus to disclose the tail loads experienced by American Airlines Flight 903 in 1997. Had they done so, "the industry would have learned several years ago that rudder reversals could be catastrophic. They failed to tell the industry, the FAA or anybody else that those rudder reversals nearly tore the tail off that A-300.

• -American Airlines’ overemphasis on the ability of wake vortices to significantly upset large aircraft such as the A-300-600 model that became AA Flight 587. The NTSB studies show that, had the pilot not responded to the second wake encounter, the aircraft would not have rolled past 34 degrees.

• -American Airlines modification of it’s A-300 simulator, which led to an emphasis on rudder use for roll control.

Trombettas says that he has a problem with all of the submissions in the sense that totally ignore any discussion of such things as the many Rockaway eyewitnesses who reported "fires, explosions and loud booming sounds before the tail separated the plane.


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