The location of the accident, and the fact that it took place two months and one day after the September 11 attacks on the World Trade Center in nearby Manhattan, initially spawned fears of another terrorist attack, but the National Transportation Safety Board (NTSB) attributed the disaster to the first officer's overuse of rudder controls in response to wake turbulence from a preceding Japan Airlines (Japan Airlines Flight 47) Boeing 747-400 that took off minutes before it. According to the NTSB, the aggressive use of the rudder controls by the first officer stressed the vertical stabilizer until it snapped off the aircraft. The airliner's two engines also separated from the aircraft before impact due to the intense forces.