"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.