On Sept. 11, 2001, the Boeing 767 left Boston's Logan Airport at 8:14 a.m., heading for Los Angeles. United 175, which had 56 passengers and nine crew members aboard, crashed into the South Tower of the World Trade Center at 9:03 a.m.
8:14 Takeoff from Logan.
8:37 Boston Center asked United 175 and other aircraft if they had seen "American 767" (American Airlines Flight 11). United 175's pilots said they had seen it. The controller directed United 175 away from it as a safety precaution.
8:41 United 175 entered New York Center's airspace. The New York Center controller responsible for United 175 was the same controller assigned the job of tracking hijacked American 11.
8:47 At almost the same time American 11 crashed into the North Tower, United 175's transponder code changed several times. The changes were not noticed for several minutes as the controller tried to locate American 11.
8:48 New York Center manager gave the following report to an FAA Command Center teleconference about American 11:
Manager, New York Center: Okay. 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.
8:51 The controller noticed the transponder reading from United 175, and asked the plane to go back to the proper code. There was no response.
8:52 The controller began to make repeated attempts to reach United 175, without getting a response.
8:53 The controller contacted another controller, worried that "we may have a hijack." Another commercial aircraft in the vicinity radioed with "reports over the radio of a commuter plane hitting the World Trade Center." The controller started to hand off other flights on his scope and moving aircraft out of the path of United 175.
8:55 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, but was told they were discussing a hijacked aircraft (presumably American 11) and refused to be disturbed.
9:01 A manager from New York Center contacted the Command Center in Herndon, Va.:
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" New York Center referred to 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 also 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 9,500-9,000 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): Alright. Heads up man, it looks like another one coming in.
9:02 The controllers observed the plane in a rapid descent; the radar data terminated over lower Manhattan.
9:03:02 United 175 crashed into the World Trade Center's South Tower.
9:03 NORAD air defenders learned of a second hijacked plane about the same time United 175 crashed into the tower.
9:05 Boston Center confirmed for both FAA Command Center and New England Region that the hijackers aboard American 11 said "we have planes" 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 the same time, New York Center declared "ATC zero." Aircraft were not permitted to depart from, arrive at, or travel through New York Center's airspace until further notice.
Boston Center's operations manager instructed all air traffic controllers in his center to inform all aircraft in Boston Center of the events unfolding in New York and to advise aircraft to heighten cockpit security. Boston Center asked the Command Center in Herndon to issue a similar cockpit security alert to all aircraft nationwide. The Sept. 11 commission found no evidence that Command Center managers instructed any centers to issue a cockpit safety alert.
9:08 The Mission Crew Commander at NEADS (the Northeast Air Defense Sector)
learned of the second explosion at the World Trade Center and advised putting F-15 fighters from Otis Air Force Base in the air space around 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 coordinate 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.
9:09 Fighters at Langley Air Force Base in Virginia were placed on battle stations to provide back-up. NORAD (North American Air Defense Command) still had no indication that any plane other than American 11 had been hijacked.
9:25 The FAA cleared the air space. Otis AFB fighters were sent to Manhattan. A Combat Air Patrol was established over the city.