Black-box recordings reveal how passengers challenged the hijackers over Pennsylvania

Investigators are increasingly convinced that passengers on board United Airlines flight 93 were involved in a frantic struggle with the hijackers who took over their plane – possibly diverting it from its intended target and causing it to crash in rural Pennsylvania.

In the aftermath of the attacks, a telephone operator reported how one of the passengers, Todd Beamer, had called from the plane, saying that it had been hijacked and that he and two other passengers, armed only with plastic butter knives, planned to take on the hijackers.

After reciting the 23rd Psalm with Mr Beamer, the operator heard the 32-year-old businessman launch into the fray with the words: "Are you guys ready? Let's roll."

Now, recordings obtained from the recovered flight recorders are providing information that supports the theory that the doomed passengers prevented the hijackers from destroying another target, possibly the White House.

The New York Times reported that the recording, which was played to the Attorney General, John Ashcroft, and the director of the FBI, Robert Mueller, suggests that a "desperate and wild" struggle took place.

Law enforcement officials told the paper that the voice recorder picked up scuffling sounds as well as shouts in Arabic and English, but experts have not yet been able to discern what was happening or determine who among the passengers, crew members or hijackers was involved in the struggle.

In the past week, officials have said that the passengers appeared to have stormed the cockpit after the four hijackers commandeered the flight. That account has been based primarily on the telephone conversations, such as the one involving Mr Beamer, between passengers and people on the ground.

Technical experts are now trying to enhance the sounds from the cockpit listening device, which uses microphones mounted in the headsets of the pilots and on the cockpit ceiling. Mr Mueller visited the crash site in Somerset, Pennsylvania last week and received a preliminary briefing on the recorder's contents. He said that the passengers heroically prevented the hijackers from striking their target.

"I think both of us here – both I and the attorney general of Pennsylvania – have indicated we believe those passengers on this jet were absolute heroes and their actions during this flight were heroic," he said.

The voice recorder from flight 93 could prove crucial to investigators. The voice recorder from American Airlines flight 77, which crashed into the Pentagon, was too damaged to provide any information. The recorders from the two planes that crashed into the World Trade Centre, American Airlines flight 11 and United Airlines flight 175,have yet to be recovered.