June 18, 2004 -- — As testimony before the 9/11 commission revealed this week, American intelligence was caught off guard as al Qaeda hijackers methodically plotted their assault on America. Air traffic controllers from Boston to New York to Washington, D.C., were among the first to realize the deadly assault was under way on the morning of Sept. 11, 2001.

The first signal of the unfolding calamity began with a strange transmission from American Airlines Flight 11, just after its takeoff from Boston.

The voice on a transmission at 8:24 a.m., believed to be that of hijacking ringleader Mohamed Atta, says, "We have some planes. Just stay quiet, and you'll be OK. We are returning to the airport."

Commission member John Azzarrello said seconds later another transmission was received by Boston air traffic controllers. "Nobody move," the voice said, "Everything will be OK. If you try to make any moves, you'll endanger yourself and the airplane. Just stay quiet."

'We Need You Guys'

Boston air traffic controllers alerted the military regarding the hijacking in progress three minutes later. "We have a problem here. 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." The Northeast Air Defense (NEADS) was unsure whether the call was some sort of drill or a real-world event.

Azzarello recounted the timeline of events. "F-15 fighters were ordered scrambled at 8:46 from Otis Air Force Base. But NEADS did not know where to send the alert fighter aircraft," Azzarello said, reading a quote from the NEADS controller. "I don't know where I'm scrambling these guys to. I need a direction, a destination."

American Airlines Flight 11 hit the North Tower of New York's World Trade Center seconds later, just as controllers realized a second jet out of Boston had also been hijacked, United Airlines Flight 175.

As the controllers observed United 175's rapid descent, the radar data terminated over lower Manhattan. Just after 9:03 a.m., United 175 crashed into the World Trade Center's South Tower.

Air traffic controller Danielle O'Brien was at the Dulles Tower outside Washington, D.C., that morning.

At 8:25 a.m. she handled the routine, on-time departure of American Airlines Flight 77 with 64 people on board. One hour and 12 minutes later it would crash into the Pentagon.

'Headed Right for the White House'

At the Dulles tower, O'Brien saw the televised pictures from New York and headed back to her post to help other planes quickly land. "We started moving the planes as quickly as we could. Then I noticed the aircraft. It was an unidentified plane to the southwest of Dulles, moving at a very high rate of speed. I had literally a blip and nothing more."

It was American 77, the flight Danielle O'Brien had handled on take-off. It disappeared from radar for 36 minutes until she spotted it, heading inbound toward the capital. O'Brien asked the controller sitting next to her, Tom Howell, if he saw it too.

"I said, 'Oh my God, it looks like he's headed to the White House,' " recalled Howell. "I was yelling … 'We've got a target headed right for the White House!' "

At a speed of about 500 mph, the plane was headed straight for what is known as P-56, prohibited air space 56, which covers the White House and the U.S. Capitol.

"The speed, the maneuverability, the way that he turned, we all thought in the radar room, all of us experienced air traffic controllers, that that was a military plane," said O'Brien. "You don't fly a 757 in that manner. It's unsafe."

It Was Just a Countdown

The plane was between 12 and 14 miles away, said O'Brien, "and it was just a countdown: 10 miles west, 9 miles west … Our supervisor picked up our line to the White House and started relaying to them the information, [that] we have an unidentified very fast-moving aircraft inbound toward your vicinity, 8 miles west."

Vice President Dick Cheney was rushed to a special basement bunker. White House staff members were told to run away from the building.

"And it went six, five, four. And I had it in my mouth to say, three, and all of a sudden the plane turned away. In the room, it was almost a sense of relief. This must be a fighter. This must be one of our guys sent in, scrambled to patrol our capital, and to protect our president, and we sat back in our chairs and breathed for just a second," said O'Brien.

But the plane continued to turn right until it had made a 360-degree maneuver.

"We lost radar contact with that aircraft. And we waited. And we waited. And your heart is just beating out of your chest waiting to hear what's happened," said O'Brien. "And then the Washington National [Airport] controllers came over our speakers in our room and said, 'Dulles, hold all of our inbound traffic. The Pentagon's been hit.' "

Two minutes later, a fourth hijacked plane, United Airlines Flight 93 out of Newark, N.J., sent out its own chilling transmission, likely the voice of hijacker Ziad Jarrah.

"Uh, this is the captain. Would like you all to remain seated," said a voice, believed to be that of Jarrah. "There is a bomb on board and are going back to the airport, and to have our demands. (inaudible). Please remain quiet."

A controller in Cleveland tried in vain to reach United 93.

During this week's testimony 9/11 panel member John Farmer detailed the exchanges between the Cleveland command center and FAA headquarters. "At about 9:36 [a.m.], Cleveland Center asked Command Center specifically whether someone had requested the military to launch fighter aircraft to intercept United 93." Just after 10:03 a.m. United 93 crashed in a Pennsylvania field, 125 miles from Washington, D.C.

Clearing the Skies

But with the sky still full of planes, no one knew and no one knows to this day, if more planes were about to be hijacked.

O'Brien recalled, "The order came to get every plane in the sky in the United States … to get them on the ground."

O'Brien said she and her fellow controllers remained calm amid the crisis. "It was a sense of urgency, it was a sense of protectiveness," she said. "Daggonnit, nobody was going to take any more, not if we could help it." According to Federal Aviation Administration radar records, almost 5,000 aircraft were safely guided to ground in under two hours.

"The air traffic controllers achieved the impossible," said John Carr, president of the National Air Traffic Controllers Association. "It was something that had never been contemplated, something that had never been practiced. And yet they did it with professionalism and skill."

Over the last 2 ½ years, O'Brien has spent a lot of time re-living that day.

"I've been down to the Pentagon and stood on the hillside and imagined where, according to what I saw on the radar, that flight would have come from, and I think that they came eastbound and because sun was in their eyes that morning, and because the White House was beyond a grove of trees, I think they couldn't see it. It was too fast," she said

"They certainly could have had the White House if they had seen it."

After the attacks, O'Brien had nightmares. "I've sat up straight in bed many times, reliving it, reseeing it, rehearing it," she said.

In her dreams, events unfold differently.

"The one that comes to mind most, dreaming of a green pool in front of me. That was part of the radar scope. It was a pool of gel, and I reached into the radar scope to stop that flight. But in the dream, I didn't harm the plane," she said. "I just held it in my hand, and somehow that stopped everything."