Posted on: Saturday, September 15, 2001
The September 11th attack
Investigators hope 'black boxes' shed clues on hijackers
Associated Press
WASHINGTON — Four airplanes heading to the West Coast suddenly switched directions Tuesday morning and eventually shut off their transponders, the devices that relay information to air traffic controllers.
But it was nothing out of the ordinary for a pilot who has problems with a plane to alter course, or even to turn around and head back to the starting point. Even after controllers learned that one of the planes had been taken over, their concern was to make sure the aircraft headed safely to whatever destination the hijackers wanted.
But unlike other hijackings, where a plane eventually lands safely and the crisis is resolved, this time terrorists used the four aircraft as a weapons. All of the passengers and crew, including the hijackers, died.
FBI investigators hope to find out what happened in those last minutes of flight by analyzing the flight data and voice recorders located in each commercial airplane's tail.
Yesterday searchers found the cockpit voice recorder from the plane that crashed in western Pennsylvania, an FBI official said. It was sent to the National Transportation Safety Board in Washington.
That means investigators have recovered four of the "black boxes" — two from American Airlines Flight 77, which hit the Pentagon, and two from United Airlines Flight 93, which crashed near Pittsburgh.
FBI Director Robert Mueller said yesterday the agency has gotten information from Flight 77's flight data recorder, which tracks an airplane's flight movements, such as altitude, heading, speed and the operations of airplane systems. He declined to say what they have found.
Mueller said the agency had not gotten any information from the voice data recorder from American Flight 77, which would have recorded all cockpit conversations and communications with air traffic controllers for the last 30 minutes. Mueller did not give information about the recovered flight data recorder from United Flight 93.
Still missing are both recorders from the two planes that destroyed the World Trade Center.
The recorders can be disabled by a pilot in the cockpit. They also can be damaged in a crash.
