Flight Recordings Probed

By CBSNews.com staff CBSNews.com staff

September 18, 2001 / 8:24 PM EDT / CBS

Twenty minutes before American Airlines Flight 11 slammed into the World Trade Center, sources say an air traffic control recording in Boston captured the sounds of the jetliner being commandeered.

"Don't do anything foolish..." one hijacker can be heard saying on the tape, "...you're not going to get hurt."

CBS News Transportation Correspondent Bob Orr reports investigators believe the radio transmission was made when one of the plane's pilots secretly keyed a microphone as a way of sending out a hijacking signal without alerting the terrorists.

That tactic may have given authorities their earliest warning of a broader attack.

Sources familiar with the tape say a hijacker can briefly be heard bragging, "We have other planes."

A second taped cockpit conversation also suggests the hijackers used the ruse of bomb scares to keep passengers from challenging them. About 30 minutes before United Flight 93 crashed in Pennsylvania, sources say air traffic controllers in Cleveland apparently heard the voice of one of the pilots just as he was confronted by the hijackers. Noise of a ruckus in the cockpit followed and then, according to the sources, one of the hijackers can be heard on the radio in what's described as a heavy Arabic accent.

"This is your Captain," he is quoted as saying, perhaps thinking he was addressing the passengers on the jet's PA system. "There is a bomb onboard. Remain seated. We are meeting their demands and returning to the airport."

The plane crashed into the earth a short time later. The impact severely damaged the jet's cockpit voice recorder. Now investigators are trying to salvage the information, hoping to find out if the hijackers talked in any detail about accomplices and other targets.