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.⁵⁰

At 9:03:11, United Airlines Flight 175 struck the South Tower of the World Trade Center.⁵¹ All on board, along with an unknown number of people in the tower, were killed instantly.

The Hijacking of American 77
American Airlines Flight 77 was scheduled to depart from Washington Dulles for Los Angeles at 8:10. The aircraft was a Boeing 757 piloted by Captain Charles F. Burlingame and First Officer David Charlebois. There were four flight attendants. On September 11, the flight carried 58 passengers.⁵²

American 77 pushed back from its gate at 8:09 and took off at 8:20. At 8:46, the flight reached its assigned cruising altitude of 35,000 feet. Cabin service would have begun. At 8:51, American 77 transmitted its last routine radio communication. The hijacking began between 8:51 and 8:54. As on American 11 and United 175, the hijackers used knives (reported by one passenger) and moved all the passengers (and possibly crew) to the rear of the aircraft (reported by one flight attendant and one passenger). Unlike the earlier flights, the Flight 77 hijackers were reported by a passenger to have box cutters. Finally, a passenger reported that an announcement had been made by the "pilot" that the plane had been hijacked. Neither of the firsthand accounts mentioned any stabbings or the threat or use of either a bomb or Mace, though both witnesses began the flight in the first-class cabin.⁵³

At 8:54, the aircraft deviated from its assigned course, turning south. Two minutes later the transponder was turned off and even primary radar contact with the aircraft was lost. The Indianapolis Air Traffic Control Center repeatedly tried and failed to contact the aircraft. American Airlines dispatchers also tried, without success.⁵⁴

At 9:00, American Airlines Executive Vice President Gerard Arpey learned that communications had been lost with American 77.This was now the second American aircraft in trouble. He ordered all American Airlines flights in the Northeast that had not taken off to remain on the ground. Shortly before 9:10, suspecting that American 77 had been hijacked, American headquarters concluded that the second aircraft to hit the World Trade Center might have been Flight 77. After learning that United Airlines was missing a plane, American Airlines headquarters extended the ground stop nationwide.⁵⁵

At 9:12, Renee May called her mother, Nancy May, in Las Vegas. She said her flight was being hijacked by six individuals who had moved them to the rear of the plane. She asked her mother to alert American Airlines. Nancy May and her husband promptly did so.⁵⁶

At some point between 9:16 and 9:26, Barbara Olson called her husband, Ted Olson, the solicitor general of the United States. She reported that the flight had been hijacked, and the hijackers had knives and box cutters. She further indicated that the hijackers were not aware of her phone call, and that they had put all the passengers in the back of the plane. About a minute into the conversation, the call was cut off. Solicitor General Olson tried unsuccessfully to reach Attorney General John Ashcroft.⁵⁷