The story of United Flight 23, the suspected fifth 9/11 plane that was grounded just in time
The aircraft never left JFK, but crew members say what happened around the flight has troubled them ever since
Among the countless stories that emerged from September 11 , one has remained unusually difficult to resolve: whether a fifth commercial jet was ever meant to join the four planes hijacked that morning.
United Airlines Flight 23 was scheduled to leave New York’s JFK Airport for Los Angeles at about 9 a.m. It had already pushed back and begun taxiing when the attacks forced authorities to shut down air traffic and send planes back to their gates.
The flight never took off. What happened before and after that decision has led several crew members to believe something far more serious may have been unfolding aboard the aircraft.
Former first officer Carol Timmons later described how the cockpit was secured as the plane returned to the terminal.
Flight attendants had reportedly become concerned about a group of passengers whose behavior stood out, including several men who appeared agitated when the departure was canceled.
“The FBI asks questions,” Timmons later said. “They don’t tell you things.”
Flight drew immediate FBI attention
Timmons and other members of the Flight 23 crew were reportedly questioned by federal investigators after the attacks.
Accounts surrounding the flight have also included claims that investigators showed crew members photographs or lineups as they tried to determine whether any of the passengers were connected to the broader 9/11 plot.
TMZ documentary 9/11: The Fifth Plane later collected testimony from pilots, flight attendants, an airline dispatcher and others who said they remained convinced Flight 23 deserved closer scrutiny.
The documentary also presented allegations that suspicious individuals may have entered or returned to the aircraft after it had been evacuated.
Other reports have claimed that box cutters and material linked to Al Qaeda were found in luggage associated with passengers from the flight.
Those claims have never been publicly confirmed in the same way as the evidence surrounding the four hijacked aircraft.
No official conclusion settled mystery
The 9/11 Commission didn't identify Flight 23 as a confirmed fifth hijacking attempt, and there has never been a publicly established finding that terrorists had definitively selected the aircraft for an attack.
That gap between witness accounts and official confirmation is why the story continues to attract attention.
Timmons and others have said the events of that morning left them convinced the shutdown of U.S. airspace may have prevented something catastrophic.
Their belief is significant, but it is still important to separate that belief from what has been formally proven. The crew was questioned. Suspicious behavior was reported. Law enforcement showed interest in the flight.
What remains unconfirmed is that Flight 23 was supposed to become the fifth hijacked plane of September 11. More than two decades later, that uncertainty is exactly what keeps the story alive.
