The 9/11 Commission Report
From Chapter 1, sections 1.1 and 1.2

These sections of chapter one detail the hijacking of United Airlines Flight 175 as it left Logan Airport in Boston for Los Angeles until it crashed into the South Tower of The World Trade Center at 9:03 AM, and the homeland defense reaction to the hijacking. [note: where possible, recordings of the actual aircraft/air traffic control transmissions have been inserted in the appropriate places]

From Chapter 1, Section 1:
The Hijacking of United 175
United Airlines Flight 175 was scheduled to depart for Los Angeles at 8:00. Captain Victor Saracini and First Officer Michael Horrocks piloted the Boeing 767, which had seven flight attendants. Fifty-six passengers boarded the flight.

United 175 pushed back from its gate at 7:58 and departed Logan Airport at 8:14. By 8:33, it had reached its assigned cruising altitude of 31,000 feet. The flight attendants would have begun their cabin service.

The flight had taken off just as American 11 was being hijacked, and at 8:42 the United 175 flight crew completed their report on a “suspicious transmission” overheard from another plane (which turned out to have been Flight 11) just after takeoff. This was United 175’s last communication with the ground.

The hijackers attacked sometime between 8:42 and 8:46. They used knives (as reported by two passengers and a flight attendant), Mace (reported by one passenger), and the threat of a bomb (reported by the same passenger). They stabbed members of the flight crew (reported by a flight attendant and one passenger).
Both pilots had been killed (reported by one flight attendant). The eyewitness accounts came from calls made from the rear of the plane, from passengers originally seated further forward in the cabin, a sign that passengers and perhaps crew had been moved to the back of the aircraft. Given similarities to American 11 in hijacker seating and in eyewitness reports of tactics and weapons, as well as the contact between the presumed team leaders, Atta and Shehhi, we believe the tactics were similar on both flights.

The first operational evidence that something was abnormal on United 175 came at 8:47, when the aircraft changed beacon codes twice within a minute. At 8:51, the flight deviated from its assigned altitude, and a minute later New York air traffic controllers began repeatedly and unsuccessfully trying to contact it.

At 8:52, in Easton, Connecticut, a man named Lee Hanson received a phone call from his son Peter, a passenger on United 175. His son told him: “I think they’ve taken over the cockpit—An attendant has been stabbed—and someone else up front may have been killed. The plane is making strange moves. Call United Airlines—Tell them it’s Flight 175, Boston to LA.” Lee Hanson then called the Easton Police Department and relayed what he had heard.

Also at 8:52, a male flight attendant called a United office in San Francisco, reaching Marc Policastro. The flight attendant reported that the flight had been hijacked, both pilots had been killed, a flight attendant had been stabbed, and the hijackers were probably flying the plane. The call lasted about two minutes, after which Policastro and a colleague tried unsuccessfully to contact the flight.

At 8:58, the flight took a heading toward New York City.

At 8:59, Flight 175 passenger Brian David Sweeney tried to call his wife, Julie. He left a message on their home answering machine that the plane had been hijacked. He then called his mother, Louise Sweeney, told her the flight had been hijacked, and added that the passengers were thinking about storming the cockpit to take control of the plane away from the hijackers.

At 9:00, Lee Hanson received a second call from his son Peter:

It’s getting bad, Dad—A stewardess was stabbed—They seem to have knives and Mace—They said they have a bomb—It’s getting very bad on the plane—Passengers are throwing up and getting sick—The plane is making jerky movements—I don’t think the pilot is flying the plane—I think we are going down—I think they intend to go to Chicago or someplace and fly into a building—Don’t worry, Dad—If it happens, it’ll be very fast—My God, my God.

The call ended abruptly. Lee Hanson had heard a woman scream just before it cut off. He turned on a television, and in her home so did Louise Sweeney. Both then saw the second aircraft hit the World Trade Center.

At 9:03:11, United Airlines Flight 175 struck the South Tower of the World Trade Center. All on board, along with an unknown number of people in the tower,were killed instantly.

From Chapter 1, Section 2:
United Airlines Flight 175
FAA Awareness. One of the last transmissions from United Airlines Flight 175 is, in retrospect, chilling. By 8:40, controllers at the FAA’s New York Center were seeking information on American 11. At approximately 8:42, shortly after entering New York Center’s airspace, the pilot of United 175 broke in
with the following transmission:

UAL 175: New York UAL 175 heavy.

FAA: UAL 175 go ahead.

UAL 175: Yeah. We figured we’d wait to go to your center. Ah, we heard a suspicious transmission on our departure out of Boston, ah, with someone, ah, it sounded like someone keyed the mikes and said ah
everyone ah stay in your seats.

FAA: Oh, okay. I’ll pass that along over here.

Minutes later, United 175 turned southwest without clearance from air traffic control. At 8:47, seconds after the impact of American 11, United 175’s transponder code changed, and then changed again. These shanges were not noticed for several minutes, however, because the same New York Center controller was assigned to both American 11 and United 175. The controller knew American 11 was hijacked; he was focused on searching for it after the aircraft disappeared at 8:46.

At 8:48, while the controller was still trying to locate American 11, a New York Center manager provided the following report on a 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.

At 8:51, the controller noticed the transponder change from United 175 and tried to contact the aircraft. There was no response. Beginning at 8:52, the controller made repeated attempts to reach the crew of United 175. Still no response. The controller checked his radio equipment and contacted another controller at 8:53, saying that “we may have a hijack” and that he could not find the aircraft.

Another commercial aircraft in the vicinity then radioed in with “reports over the radio of a commuter plane hitting the World Trade Center.” The controller spent the next several minutes handing off the 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, 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, 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 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” referred to by New York Center was United 175. Evidence indicates that this conversation was the only notice received by either FAA headquarters or the Herndon Command Center prior to the second crash that there had been a second hijacking.

While the Command Center was told about this “other aircraft” at 9:01, 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 9,500—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.

The controllers observed the plane in a rapid descent; the radar data terminated over Lower Manhattan. At 9:03, 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: . . . as far as the tape, Bobby 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. Okay?

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: Okay.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 departures at airports under its control. At 9:05, Boston Center confirmed for both the FAA Command Center and the New England Region that the hijackers aboard American 11 said “we have planes.” At the same time, New York Center declared “ATC zero”—meaning that aircraft were not permitted to depart from, arrive at, or travel through New York Center’s airspace until further notice.

Within minutes of the second impact, Boston Center instructed its controllers to inform all aircraft in its airspace of the events in New York and to advise aircraft to heighten cockpit security. Boston Center asked the Herndon Command Center to issue a similar cockpit security alert nationwide.We have found no evidence to suggest that the Command Center acted on this request or issued any type of cockpit security alert.

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. The notice came at about the time the plane was hitting the South Tower.

By 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 airspace 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 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.

The FAA cleared the airspace. Radar data show that at 9:13, when the Otis fighters were about 115 miles away from the city, the fighters exited their holding pattern and set a course direct for Manhattan. They arrived at 9:25 and established a combat air patrol (CAP) over the city.

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 refueling. NEADS considered scrambling alert fighters from Langley Air Force Base in Virginia to New York, to provide backup. The Langley fighters were placed on battle stations at 9:09. NORAD had no indication that any other plane had been hijacked.