At 8 a.m. on Sept. 11, 2001, American Airlines Flight 11 began its takeoff roll at Logan Airport in Boston. A Boeing 767, Flight 11 was bound for Los Angeles with 81 passengers, 11 crew, and more than 90,000 litres of jet fuel. By 8:09 a.m., it was being monitored by the Federal Aviation Administration's Boston Center (located in New Hampshire). At 8:13 a.m., the controller instructed the flight to "turn 20 degrees right," which the flight acknowledged. This was the last transmission to which the flight responded.

Sixteen seconds later, the controller instructed the flight to climb to 35,000 feet (10,668 metres). When there was no response, the controller repeated the command seconds later, and then tried repeatedly to raise the flight. He used the emergency frequency to try to reach the pilot. Although there was no response, he kept trying to contact the aircraft.

At 8:21 a.m., American 11 turned off its transponder, immediately degrading the available information about the aircraft. The controller told his supervisor that he thought something was seriously wrong. At this point, neither the controller nor his supervisor suspected a hijacking. The supervisor instructed the controller to follow standard operating procedures for handling a ``no radio" aircraft.

The controller checked to see if American Airlines could establish communication with American 11. He became even more concerned as its route changed, moving into another sector's airspace. Controllers immediately began to move aircraft out of its path, and searched from aircraft to aircraft in an effort to have another pilot contact American 11. At 8:24:38, the following transmission came from American 11:

AMERICAN 11: We have some planes. Just stay quiet, and you'll be OK. We are returning to the airport.

The controller only heard something unintelligible; he did not hear the specific words "we have some planes." Then the next transmission came seconds later:

AMERICAN 11: Nobody move. Everything will be OK. If you try to make any moves, you'll endanger yourself and the airplane. Just stay quiet.

The controller realized it was a hijacking. He alerted his supervisor, who assigned another controller to assist, and redoubled efforts to determine the flight's altitude. Because the controller didn't understand the initial transmission, the manager of Boston Center instructed a centre specialist to "pull the tape" of the radio transmission, listen to it and report back.

Between 8:25 and 8:32 a.m., Boston Center managers started notifying their chain of command that American 11 had been hijacked. At 8:28 a.m., Boston Center called the Command Center in Herndon, Va., to advise management that it believed American 11 had been hijacked and was heading toward New York Center's airspace. By this time, American 11 had taken a dramatic turn to the south. At 8:32 a.m., the Command Center passed word of a possible hijacking to the Operations Center at FAA headquarters. The duty officer replied that security personnel at headquarters had just begun discussing the hijack situation on a conference call with the New England Regional office.

The Herndon Command Center immediately established a teleconference between Boston, New York, and Cleveland Centers so that Boston Center could help the others understand what was happening.

At 8:34 a.m., the Boston Center controller received a third transmission from American 11:

AMERICAN 11: Nobody move please. We are going back to the airport. Don't try to make any stupid moves.

Boston Center did not follow routine protocol in seeking military assistance through the prescribed chain of command. In addition to making notifications within the FAA, Boston Center took the initiative, at 8:34 a.m., to contact the military through the FAA's Cape Cod facility. They also tried to obtain assistance from a former alert site in Atlantic City, unaware it had been phased out. At 8:37:52 a.m., Boston Center reached Northeast Air Defence Sector (NEADS). This was the first notification received by the military at any level that American 11 had been hijacked:

FAA: Hi. Boston Center TMU, 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, help us out.

NEADS: Is this real-world or exercise?

FAA: No, this is not an exercise, not a test.

NEADS promptly ordered to battle stations the two F-15 alert aircraft at Otis Air Force Base, about 245 kilometres from New York City. The air defence of America began with this call.

At NEADS, the reported hijacking was relayed to battle commander Col. Robert Marr. After ordering the Otis fighters to battle stations, Marr phoned Maj.-Gen. Larry Arnold, commanding general of the First Air Force and the Continental Region. Arnold instructed Marr "to go ahead and scramble the airplanes, and we'd get permission later." Arnold then called NORAD headquarters to report.

F-15 fighters were ordered scrambled at 8:46 a.m. from Otis Air Force Base. But NEADS didn't know where to send the alert fighter aircraft. Because the hijackers had turned off the plane's transponder, NEADS personnel spent the next minutes searching their radar scopes.

American 11 hit the World Trade Center's North Tower at 8:46:40 a.m. Shortly after 8:50 a.m., while NEADS personnel were still trying to locate American 11, word reached them that a plane had struck.

Radar data show the Otis fighters were airborne at 8:53 a.m. Lacking a target, they were vectored toward military-controlled airspace off the Long Island coast. To avoid New York-area air traffic and uncertain about what to do, the fighters were brought down to military air space to "hold as needed." From 9:08 a.m. to 9:13 a.m., the Otis fighters were in this holding pattern.

United Airlines Flight 175, a Boeing 767 carrying 65 passengers from Boston to Los Angeles, left Logan Airport at 8:14 a.m. At 8:37, Boston Center polled United 175 and other aircraft about whether they had seen an “American 767” (American 11), and United 175’s pilots said they had. The controller turned United 175 away from it as a safety precaution.

At 8:41 a.m., United 175 entered New York Center’s airspace. The controller responsible was the same one assigned the job of tracking the hijacked American 11. At 8:47 a.m., at almost the same time American 11 crashed into the North Tower, United 175’s assigned transponder code changed, then changed again. These changes were not noticed for several minutes, because the controller was focused on finding American 11, which had disappeared. At 8:48 a.m., a New York Center manager provided the following report on a Command Center teleconference about American 11, including information that had been relayed by the airline:

MANAGER, NEW YORK CENTER: OK. This is New York Center. We’re watching the airplane. I also had conversation with American Airlines, and they’ve told us that they believe that one of their stewardesses was stabbed and that there are people in the cockpit that have control of the aircraft, and that’s all the information they have right now.

The New York Center controller and manager were unaware that American 11 had already crashed.

At 8:51 a.m., the controller noticed the change in the transponder reading from United 175. The controller asked United 175 to go back to the proper code. There was no response. Beginning at 8:52 a.m., the controller made repeated attempts to reach the crew, without response.

Another commercial aircraft in the vicinity called in with ``reports over the radio of a commuter plane hitting the World Trade Center.” The controller spent the next several minutes handing off other flights on his scope to other controllers and moving aircraft out of the way of the unidentified aircraft — believed to be United 175 — as it moved southwest and then turned northeast toward New York City.

At about 8:55 a.m., the controller in charge notified a New York Center manager that she believed United 175 had also been hijacked. The manager tried to notify the regional managers and was told that they were discussing a hijacked aircraft — presumably American 11 — and refused to be disturbed. At 8:58 a.m., the New York Center controller searching for United 175 told another New York controller ``we might have a hijack over here, two of them.”

Between 9:01 and 9:02 a.m., a manager from New York Center told the Command Center in Herndon:

MANAGER, NEW YORK CENTER: We have several situations going on here. It’s escalating big, big time. We need to get the military involved with us. ... We’re, we’re involved with something else, we have other aircraft that may have a similar situation going on here. ...

The “other aircraft” was United 175. Evidence indicates that this conversation was the only notice received prior to the second crash by either FAA headquarters or the Herndon Command Center that there was a second hijack. New York Center contacted New York terminal approach control and asked for help in locating United 175.

TERMINAL: I got somebody who keeps coasting but it looks like he’s going into one of the small airports down there.

CENTER: Hold on a second. I’m trying to bring him up here and get you ... there he is right there. Hold on.

TERMINAL: Got him just out of 9,5009,000 now.

CENTER: Do you know who he is?

TERMINAL: We’re just, we just we don’t know who he is. We’re just picking him up now.

CENTER (at 9:02 am.): All right. Heads up, man, it looks like another one coming in.

The controllers observed the plane in a rapid descent; the radar data terminated over lower Manhattan. At 9:03:02 a.m., United 175 crashed into the South Tower. Meanwhile, a manager from Boston Center reported that they had deciphered what they had heard in one of the first hijacker transmissions from American 11:

BOSTON CENTER: Hey, you still there?

NEW ENGLAND REGION: Yes, I am.

BOSTON CENTER: I’m gonna reconfirm with, with downstairs, but the, as far as the tape seemed to think, the guy said that “we have planes.” Now, I don’t know if it was because it was the accent, or if there’s more than one, but I’m gonna, I’m gonna reconfirm that for you, and I’ll get back to you real quick. OK?

NEW ENGLAND REGION: Appreciate it.

UNIDENTIFIED FEMALE VOICE: They have what?

BOSTON CENTER: Planes, as in plural.

BOSTON CENTER: It sounds like, we’re talking to New York, that there’s another one aimed at the World Trade Center.

NEW ENGLAND REGION: There’s another aircraft?

BOSTON CENTER: A second one just hit the Trade Center.

NEW ENGLAND REGION: OK. Yeah, we gotta get ... we gotta alert the military real quick on this.

Boston Center immediately advised the New England region that it was going to stop all aircraft scheduled to depart from any airport within Boston Center. At 9:05 a.m., Boston Center confirmed for both FAA Command Center and New England region that the hijackers aboard American 11 said “we have planes.” At the same time, New York Center declared “ATC zero” meaning aircraft were not permitted to depart from, arrive at or travel through New York Center’s airspace until further notice.

Military Notification and Response:

The first indication that the NORAD air defenders had of the second hijacked aircraft, United 175, came in a phone call from New York Center to NEADS at 9:03 a.m., around the time the plane was hitting the South Tower. At 9:08, the Mission Crew commander at NEADS learned of the second explosion at the World Trade Center and decided against holding the fighters in military air space away from Manhattan:

MISSION CREW COMMANDER, NEADS: This is what I foresee that we probably need to do. We need to talk to FAA. We need to tell ’em if this stuff is gonna keep on going, we need to take those fighters, put ’em over Manhattan. That’s best thing, that’s the best play right now. So co-ordinate with the FAA. Tell ’em if there’s more out there, which we don’t know, let’s get ’em over Manhattan. At least we got some kind of play.

The FAA cleared the air space. The Otis fighters were sent to Manhattan. A Combat Air Patrol was established over the city at 9:25 a.m.

Because the Otis fighters had expended a great deal of fuel in flying first to military airspace and then to New York, the battle commanders were concerned about refuelling. NEADS considered scrambling alert fighters from Langley Air Force Base in Virginia to New York, to provide back-up. The Langley fighters were placed on battle stations at 9:09 a.m. NORAD had no indication that any other plane had been hijacked.

American 77 began its takeoff from Dulles International Airport at 8:20 a.m. The flight was handed off routinely from Washington Center to Indianapolis Center at approximately 8:40 a.m.

The Indianapolis controller, who had 14 other planes in his sector at the time, instructed the aircraft to climb.

At 8:54 a.m., American 77 began deviating from its flight plan, first with a slight turn toward the south. Two minutes later it disappeared from Indianapolis radar.

Shortly after 9 a.m., Indianapolis Center started notifying other agencies that American 77 was missing and had possibly crashed. At 9:08 a.m., Indianapolis Center contacted Air Force Search and Rescue at Langley Air Force Base in Virginia and told them to look out for a downed aircraft.

By 9:20 a.m., Indianapolis Center learned that there were other hijacked aircraft in the system, and began to doubt their initial assumption that American 77 had crashed.

According to radar reconstruction, American 77 re-emerged as a primary target on Indianapolis Center radar scopes at 9:05 a.m., east of its last known position. The target remained in Indianapolis Center’s airspace for another six minutes, then crossed into the western portion of Washington Center’s airspace at 9:10 a.m.

Indianapolis Center never saw Flight 77 turn around. By the time it reappeared in primary radar coverage, controllers had either stopped looking for the aircraft because they thought it had crashed or were looking toward the west. In addition, while the Command Center learned Flight 77 was missing, neither it nor FAA headquarters had issued an “all points bulletin” to surrounding centres to search for primary radar targets. American 77 travelled undetected for 36 minutes on a course heading east for Washington, D.C.

By 9:25 a.m., FAA’s Herndon Command Center and FAA headquarters knew two aircraft had crashed into the World Trade Center; that American 77 was lost; that a hijacker on board American 11 had said ``we have some planes,” and concerns over the safety of other aircraft began to mount.

A manager at the Herndon Command Center asked FAA headquarters if they wanted to order a “nationwide ground stop.” While executives at FAA headquarters discussed it, the Command Center went ahead and ordered it at 9:25 a.m.

The Command Center kept looking for American 77. At 9:21 a.m., it advised the Dulles terminal control facility, which urged its controllers to look for primary targets. At 9:32 a.m., they found one. Several of the Dulles controllers “observed a primary radar target tracking eastbound at a high rate of speed” and notified Reagan Airport. FAA personnel at both Reagan and Dulles airports notified the Secret Service. The identity or aircraft type was unknown.

Reagan Airport controllers then vectored an unarmed National Guard C-130H cargo aircraft, which had just taken off en route to Minnesota. The C-130H pilot spotted it, identified it as a Boeing 757, attempted to follow its path, and at 9:38 a.m., seconds after impact, reported to Washington Tower: “Looks like that aircraft crashed into the Pentagon, sir.”

At 9:21 a.m., NEADS received a report from the FAA:

FAA: Military, Boston Center. I just had a report that American 11 is still in the air, and it’s on its way towards, heading towards Washington.

NEADS: OK. American 11 is still in the air?

FAA: Yes.

NEADS: On its way towards Washington?

FAA: That was another… it was evidently another aircraft that hit the tower. That’s the latest report we have.

NEADS: OK.

FAA: I’m going to try to confirm an ID for you, but I would assume he’s somewhere over, uh, either New Jersey or somewhere further south.

NEADS: Okay. So American 11 isn’t the hijack at all then, right?

FAA: No, he is a hijack.

NEADS: He… American 11 is a hijack?

FAA: Yes.

The Mission Crew Commander at NEADS issued an order at 9:23 a.m.: “Okay scramble Langley. Head them towards the Washington area.” That order was processed and transmitted to Langley Air Force Base at 9:24 a.m., and radar data show the Langley fighters were airborne at 9:30 a.m.

NEADS decided to keep the Otis fighters over New York. The heading of the Langley fighters was adjusted to send them to the Baltimore area. The Mission Crew Commander explained that the purpose was to position the Langley fighters between the reported southbound American 11 and the capital.

At the suggestion of the Boston Center’s military liaison, NEADS contacted the FAA’s Washington Center to ask about American 11. In the course of the conversation, a Washington Center manager informed NEADS that “We’re looking…we also lost American 77.”

At 9:38 a.m., the Pentagon was struck by American 77.