Mohamed Atta | Flight 11 on 9/11

A voice believed to be that of al Qaeda hijack leader Mohamed Atta urged passengers to "stay quiet and you'll be OK" as the hijackers steered American Airlines Flight 11 toward New York.

"Nobody move. Everything will be OK," the voice said in a recording first played publicly in the commission's final hearing.

"If you try to make any moves, you'll endanger yourself and the airplane. Just stay quiet," the voice said.

The announcement, which commission staff believe was from Atta, was the first transmission from the aircraft picked up by air traffic controllers in Boston, where the flight originated.

Ten minutes later, the voice again warned, "Nobody move please. We are going back to the airport. Don't try to make any stupid moves."

The Egyptian-born Atta apparently was not aware that his announcements to passengers were being broadcast.

The recording was played as the commission examined a report by its staff that said the U.S. military and the Federal Aviation Administration were unprepared "in every respect" to stop the hijackings, in which Atta and other al Qaeda operatives crashed passenger jets into the World Trade Center, the Pentagon and a Pennsylvania field.

Nearly 3,000 people died in the attacks.

The first word of the hijacking reached the FAA about a half-hour into the flight. And the Northeast Air Defense Sector base in Rome, New York, received its first notification at 8:37 a.m. -- just nine minutes before Flight 11 crashed into the World Trade Center's north tower.

"The nine minutes' notice was the most the military would receive that morning of any of the four hijackings," the report said.

Two Air Force F-15s were dispatched from an Air Force base in Massachusetts, but they were not airborne until 8:53 a.m.

On three of the four planes, the hijackers turned off transponders that best enable air traffic controllers to follow a plane's path.

'It's escalating big, big time'
The same air traffic controller handling Flight 11 was also responsible for United Airlines Flight 175, the second hijacked plane. The Boston-to-Los Angeles flight crashed into the Trade Center's south tower at 9:03 a.m.

At 8:51 a.m., the controller noticed a change in Flight 175's transponder reading, indicating a second hijacking. But it wasn't until 9:01 a.m., two minutes before impact, that the air traffic control center in Herndon, Virginia, got the word.

"It's escalating big, big time. We need to get the military involved with us," the manager of the New York air traffic center said. NORAD didn't get a call until 9:03 a.m. -- the same time the second plane hit the World Trade Center.