At about 9:58, the hijackers realized that the passengers were starting to revolt.

In Arabic someone says, "Is there something? A fight?" Another hijacker responds, "Yeah.

"Roll it," a person outside the cockpit yelled, apparently referring to the cart. "In the cockpit. If we don't we die," a voice said.

The hijacker pilot began rocking the plane violently from side to side, while a hijacker chanted in Arabic "Allah is greatest."

Crashing and banging noises could be heard, interspersed with "ugh" sounds and the sound of breaking glass or dishes.

"They want to get in there," a hijacker said. "Hold, hold from the inside, hold from the inside."

The hijackers conferred about whether it was time to crash the plane then said "Allah is the greatest" several times before the plane plowed into the field around 10:03 a.m.

The tape was played in 2002 for families of the victims aboard the doomed plane, but the families were ordered not to reveal the contents.

Passenger heroism 

Families of September 11 victims said the first public airing of United Airlines Flight 93's cockpit recording shows passengers' heroism - but some decided it would be too painful to hear the last words of those who died.

"I don't want to hear it. I deliberately did not go to court. I can't hear that tape," said Debra Burlingame, whose brother, Charles, was the pilot on the hijacked plane that crashed into the Pentagon.

"It mirrors what happened in my brother's cockpit," she said. "It's just too unbearable to hear the sounds of that slaughter."

Forty people were killed when Flight 93 crashed in a western Pennsylvania field on September 11, 2001.

The first recording to be heard from any of the four hijacked planes on September 11 was played for a federal jury deciding whether conspirator Zacarias Moussaoui deserves to be executed.

On the recording, passengers and hijackers struggle in the cockpit for control of the plane, and one man says, "I'm injured."

That man was Tom Burnett, said his parents, who had already heard the recording. "We are very sure that he led the effort to take the plane back," said Burnett's father, Tom, on Wednesday.

Beverly Burnett said she wished the tape could be played outside the Virginia courtroom.

"We feel that everyone should know what went on in that plane and how horrible it was. I think they will understand what our son did on the plane."

For Burlingame, who watched most of Moussaoui's trial either in Alexandria, Va., or from a closed-circuit hookup in New York, the phase of the trial dealing with the attacks' impact was too painful to see in person.

"Your nightmares are vivid enough. To have them even more vivid, I can't put that on myself," she said.

She also supported a decision not to release the audiotape of the Flight 93 recording outside the courtroom, while saying the testimony is necessary to show the world the consequences of terrorism.

"This is an opportunity for all of the world to see the face of the enemy," Burlingame said. "To me that is important as the disposition of the case against Moussaoui."

In New York's federal court, a handful of people watching the proceedings via closed circuit included Elsa Rensaa, a World Trade Center survivor who said that hearing the cockpit recording debunked some conspiracy theories.

"It clears up the fact that the U.S. Air Force did not shoot down the plane in Pennsylvania," Rensaa said. "You could hear from the cockpit voice recorder that the hijackers flew wildly and erratically to get people away from the door."

Clayton Patterson, another survivor, called the trial a chance to air key facts and dispel myths about September 11.

"People really did try to defend the plane and make something happen," he said.