2004-04-02 / Front Page

‘Time For Science And Safety To Override Economics’

Pilots Say Airbus Knew of Unsafe Control System Since 1997
By Howard Schwach
‘Time For Science And Safety To Override Economics’ Pilots Say Airbus Knew of Unsafe Control System Since 1997 By Howard Schwach

Bad economics has driven out good science and common sense in the airline industry, a fact that helped to cause the disastrous crash of American Airlines Flight 587 into Belle Harbor in November of 2001, the Allied Pilots Association, the union representing the pilots, said in a submission to the National Trans portation Safety Board (NTSB) last month.

Flight 587, an Airbus A300, crashed into Beach 131 Street and Newport Avenue shortly after it took off from Runway 31 Left at John F. Kennedy Airport.

The pilots say that a flaw in the A-300’s control system caused the crash by confusing the first officer, who was flying the plane on its departure from JFK, to such an extent that he over-controlled the rudder causing it to separate from the plane’s fuselage.

"The probable cause of this accident was an Aircraft Pilot Coupling (APC) event. This APC occurrence was the result of a flawed design modification to the A300," the union said in its submission. "The APC event led to the development of excessive aerodynamic loads and consequent structural failure of the vertical stabilizer in only 6.5 seconds. Airbus was forewarned of this catastrophe by preceding in-service events and failed to caution operators and regulators of this tendency."

"An APC is usually the result of a deficient flight control design," the pilot’s submission continued. "An APC event causes a pilot’s rudder inputs to be out of sync with the motion of the aircraft. In the case of Flight 587, the Pilot Flying – uninformed and unaware of the hypersensitive rudder peddles – made appropriate and controlled rudder inputs in response to the aircraft’s motion as it encountered wake vortices. An unintentional result was that excessively high aerodynamic loads were placed on the vertical stabilizer which then broke off the aircraft only 9 seconds after the first rudder pedal input."

The submission posits that a wake vortex from a Japan Airlines Boeing 747-400 aircraft that took off just prior to Flight 587, impacted the plane just before it approached Rockaway’s Jamaica Bay coastline.

While the planes were mandated to keep a two-minute separation to avoid wake vortex events, the pilots say that when the A300 turned towards WAVEY, a waypoint about 35 miles southeast of Rockaway, that brought the aircrafts inside the mandated separation.

The submission says, "AA 587 took off from Runway 31 L with the required two minutes of separation from JAL 47. Upon departing, the Air Route Traffic Control Center (ARTCC) gave the accident aircraft a turn to the WAVEY intersection. This vector placed the American [Airlines] airplane inside the turn of the preceding 747, effectively creating a rendezvous turn. The turn immediately reduced the separation between the two aircraft, exposing AA 587 to a more powerful wake vortex than the departure separation should have assured. These hazards occurred without the knowledge of the 587 flight crew, inadvertently exposing them to dramatically increased risk."

That risk was the beginning of the end for the flight, which carried 280 passengers and crew, something the union believes, could have been avoided had there been more separation between the planes.

"AA 587’s flight path was disturbed by two potentially destructive wake vortices generated by the Boeing 747-400 aircraft. Wake turbulence issues have been clouded by economic influences, particularly airport capacity. The most direct fix of this problem is to increase separation. This is also the most opposed solution due to its economic impact," the report says, adding, "It is time for safety and science to override economics."

The pilot’s union also believes that, once the pilots were in the APC event, there was little they could do to get out of it.

"The National Research Council (NRC) believes that the most severe APC events attributed to pilot error are the result of adverse APC that misleads the pilot into taking actions that contribute to the severity of the event. In these situations, it is often possible, after the fact, to analyze the event carefully and identify a sequence of actions the pilot could have taken to overcome the aircraft design deficiencies and avoid the event. However, it is typically not feasible for the pilot to identify and execute the required actions in real time," the submission says.

What exacerbated the problem, the pilots say, is the fact that Airbus, the manufacturer of the plane, knew of the problem from earlier "upsets" of A300 aircraft related to rudder problems as early as 1997, yet never warned either the FAA nor the NTSB nor any European agency involved with aircraft safety.

"An [adequate] training program could not have been developed," the pilots say. "The manufacturer offered no information about the limitations or peculiarities of the rudder system. Neither pilot was trained to experience this unexpected and unpredictable flight characteristic nor the aircraft gyrations experienced in the accident sequence. It was far beyond the pilot’s practical experience, surprising the PF [Pilot Flying] and leaving the PIC [Pilot In Charge] unaware of the peril they faced as the PF struggled to maintain control of the aircraft."

Airbus’ submission to the NTSB denies that the A300 has a design flaw, insisting instead that American Airlines failed to adequately train its pilots to fly the plane.


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