The most complete picture of the confusion among air-traffic controllers, pilots and the military during the terrifying chaos of the 9/11 hijackings has been released ahead of the 10th anniversary of the attacks.
The chilling collection of 114 audio recordings spans two hours and captures the desperate efforts of those involved to understand and deal with the unfolding atrocity.
Parts of the audio recordings have been aired before, but others had not been heard.
Days ahead of the 10th anniversary of the attacks, they have now been published in an unprecedented blow-by-blow recreation of events.
The recordings begin at 8.13am when air-traffic controllers in Boston lose touch with American Airlines Flight 11. Six minutes later flight attendant Betty Ong, tells the ground: "Somebody's stabbed in business class, and I think there is mace that we can't breathe. I think we're getting hijacked."
At 8.24am the voice of hijacker Mohamed Atta can be heard saying the plane is returning to the airport. He says: "Nobody move, everything will be okay. If you try to make any moves, you will injure yourself and the aeroplane. Just stay quiet."
The tapes show how ground controllers desperately tried to keep up with events. Sixteen minutes after the first hijacked plane hit the World Trade Centre a radio transmission was received at the New York air-traffic control radar centre telling them to look out their window at a low-flying aircraft.
After one plane had already hit, and with the second moments from impact, an air-traffic control manager in New York called the Federal Aviation Administration headquarters in Herndon, Virginia, to ask if military jets were being scrambled. The reply from Virginia came: "Why, what's going on?"
During the chaos an unidentified pilot is heard asking over the airwaves: "Anybody know what that smoke is in lower Manhattan?" In another recording someone asks: "Is this real world or exercise?"
The recordings were originally compiled as an "audio monograph" for the 9/11 Commission, but the work was not completed in time before the commission concluded its business.
Miles Kara, a commission investigator, found the remaining files in the National Archives and transcribed them with the help of Rutgers University.
Mr Kara said: "The story of the day of 9/11 itself is best told in the voices of 9/11."
Two recordings have still not been published. One is a 30-minute tape from the cockpit of United Airlines Flight 93 that crashed in Pennsylvania when passengers stormed the hijackers. Families of victims objected to it being released.
A recording of a conference call which started at 9.28am and involved then Vice-President Dick Cheney and Defence Secretary Donald Rumsfeld is also not included.