Air traffic controllers can be heard trying to make sense of the unfolding 9/11 terror attacks in a series of newly-released audio recordings from the morning of September 11, 2001.

The recordings, part of the 9/11 Commission material stored in the National Archives, have been organized for public release by students of the Rutgers University School of Law, whose dean is a former 9/11 Commission senior counsel.

The audio is part of a complete chronology of the 9/11 attacks published by the Rutgers Law Review.

On the recordings, air traffic controllers, members of the military and pilots are heard as the events of the day unfolded.

"Hi, Boston Center, T.M.U. (traffic management unit), we have a problem here," one of the controllers is heard saying in one clip. "We have a hijacked aircraft headed towards New York and we need you guys to, we need someone to scramble some F-16s or something up there to help us out."

Another clip records the reaction as a plane strikes one of the towers.

"Another one just hit the building," the speaker says. "Wow. Another one just hit it hard. Another one just hit the World Trade."

Also heard on the recordings is a discussion among military personnel in which Vice President Dick Cheney gave fighter jet pilots permission to shoot down the hijackers.

Hijackers can also be heard entering the cockpit of United Flight 93.

There is also audio of stunned air traffic controllers describing the events.

Much of the audio released had been previously documented at the 9/11 hearings.

Some original recordings from 9/11 have still not been made public, including military communications and discussions with the White House.