Airbus charged that the crash was mostly American Airlines' fault, arguing that the airline did not train its pilots properly about the characteristics of the rudder. Aircraft tail fins are designed to withstand full rudder deflection in one direction when below maneuvering speed, but this does not guarantee that they can withstand an abrupt shift in rudder from one direction to the other, let alone multiple abrupt shifts, like those generated by the first officer on this flight. The NTSB indicated that American Airlines' Advanced Aircraft Maneuvering Program (AAMP) tended to exaggerate the effects of wake turbulence on large aircraft, creating a simulation scenario whereby turbulence from a 747 creates a 90° roll (rather than the likely 5 to 10° roll, though not explaining this to the pilots) to maximize the training challenge. Therefore, pilots were being inadvertently trained to react more aggressively than was necessary. According to author Amy Fraher, this led to concerns of whether it was appropriate for the AAMP to be placing such importance on "the role of flight simulators in teaching airplane upset recovery at all." Fraher states that the key to understanding the crash of Flight 587 ultimately lay in "how the accident pilots' expectations about aircraft performance were erroneously established through 'clumsy' flight simulator training in American's AAMP."