Captain Tom Mannello, who was preparing United Airlines Flight 23 for departure from John F. Kennedy International Airport on the morning of Sept. 11, 2001, told a Channel 5 documentary that he now believes there is a "good chance" his aircraft was intended to be a fifth hijacked plane in the attacks that killed 2,977 people.
Mannello and several flight attendants said they were moments from takeoff when air traffic control ordered all flights returned to gates after the second plane struck the World Trade Center at 9:03 a.m. He recounted learning later that two box cutters had been found in the first-class seat pockets of an aircraft parked directly beside his, and that the adjacent plane’s tail number differed from Flight 23’s by only one digit. Mannello said that sequence of facts led him to conclude the weapons may have been placed on the wrong aircraft.
"I now believe that it is more likely than not that we were the fifth airplane," Mannello said in the documentary. "I think it's a reasonable assumption to think that those box cutters were meant for my airplane, not the one next to me." He said the only thing he could identify as a likely explanation was an error by someone with access to ground-servicing operations who placed the items on the wrong plane.
Flight attendants who were aboard Flight 23 described behavior among several first-class passengers that, in retrospect, struck them as suspicious. Barbara Brockie-Smaldino said she observed a passenger wearing a burka and niqab who she believed to be a man. Sandy Thorngren said another man in first class appeared sweaty and nervous, and she recalled an individual asking to take a child into the cockpit — a request that is ordinarily prohibited. Crew members also said first-class passengers repeatedly declined meal service before takeoff.
Mannello and his crewmembers’ recollections were presented in a Channel 5 documentary broadcast on the 24th anniversary of the attacks. The accounts represent the crew’s interpretations of events at the time and subsequent evidence they say they collated. The 9/11 Commission’s final report does not list United Flight 23 as one of the hijacked aircraft, and there were no confirmed arrests connected to Flight 23 as part of the government’s investigation, officials said. U.S. authorities have not publicly commented on the crew’s assertions.
On Sept. 11, 2001, four commercial airliners were hijacked and deliberately crashed into American landmarks. American Airlines Flight 11, departing Boston for Los Angeles, struck the North Tower of the World Trade Center at 8:46 a.m. United Airlines Flight 175, also from Boston to Los Angeles, hit the South Tower at 9:03 a.m. American Airlines Flight 77, departing Washington, D.C., crashed into the Pentagon at 9:37 a.m. United Airlines Flight 93, which left Newark bound for San Francisco, went down in a field near Shanksville, Pennsylvania, at 10:02 a.m., after passengers attempted to retake control. The attacks killed 2,977 people, excluding the 19 hijackers.
After the attacks, law enforcement authorities detained more than 1,200 people for questioning, and the U.S. established a detention facility at Guantánamo Bay, Cuba, to hold terrorism suspects. The camp, which once held hundreds, has been reduced to a small number of detainees. Osama bin Laden, the al-Qaeda leader who claimed responsibility for the attacks, was killed in Pakistan by U.S. special operations forces on May 2, 2011.
The Sept. 11 attacks prompted the U.S.-led invasion of Afghanistan in October 2001 to remove the Taliban government that had harbored al-Qaeda, and later contributed to the 2003 U.S. invasion of Iraq. Investigations, prosecutions and intelligence operations stemming from the attacks continued for years. Khalid Sheikh Mohammed, accused of being the operational planner of the attacks, has been held at Guantánamo Bay for years while legal proceedings have been repeatedly delayed.
Mannello and his crewmembers said they are presenting their recollections in the documentary to explain why they believe their aircraft narrowly avoided being used in the attacks. Their account rests on their personal observations from that morning and the subsequent discovery of the box cutters on an adjacent plane. The documentary aired amid broader public remembrance of the scale and aftermath of the Sept. 11 attacks but did not present new official investigative findings concerning Flight 23.
U.S. investigative agencies completed extensive inquiries into the attacks in the months and years that followed, resulting in the 9/11 Commission Report and multiple criminal and intelligence investigations. Those official records attribute the four deadly crashes to 19 hijackers affiliated with al-Qaeda and do not identify a separate fifth aircraft used in the plot. Mannello and his colleagues said their experience has left them convinced an additional attempt was narrowly averted on that morning, a conclusion they attribute to the misplaced box cutters and to behaviors they found troubling at the time.
Their account adds to the body of personal testimonies from Sept. 11 that continue to shape public understanding of the attacks and the immediate chaos at American airports that morning. Officials who oversaw the government’s response and the official 9/11 investigations have not added comment on the Flight 23 claims presented in the Channel 5 program.