New Documentary Raises Questions About a Possible Fifth Plane on 9/11, Alleging FBI Cover-Up

A new documentary by TMZ, titled TMZ Investigates: 9/11: The Fifth Plane, has reignited speculation about a potential fifth plane targeted by hijackers during the September 11, 2001, terrorist attacks. The documentary, which aired on Fox in March 2023 and became available on YouTube in June 2025, presents interviews with the pilot and three flight attendants of United Airlines Flight 23, a Boeing 767 scheduled to depart from New York’s JFK Airport to Los Angeles at 9 a.m. on that fateful day. The crew alleges suspicious activities aboard the plane, including an unexplained opened hatch and questionable passenger behavior, which they believe point to a thwarted hijacking attempt covered up by the FBI.

According to the documentary, United Flight 23 was taxiing to the runway when the second plane struck the World Trade Center, prompting the grounding of all U.S. flights. The plane returned to the gate, and passengers and crew were evacuated. Pilot Tom Mannello, who features prominently in the documentary, claims that after the plane was “locked and sealed,” authorities discovered a hatch in the floor of the main cabin—leading to an electronics compartment and an external hatch on the plane’s underside—had been mysteriously opened. “The airplane was locked and sealed when I left the airplane, so something else was going on that I couldn’t explain,” Mannello told TMZ. He speculated that someone may have accessed the plane to remove incriminating evidence, such as weapons.

Flight attendants Sandy Thorngren, Barbara Brockie Smaldino, and another unnamed crew member reported suspicious behavior from four passengers in first class, described as “Arabs” in the documentary. The group, which included a man allegedly disguised in a burqa, a young boy, and two other men, reportedly demanded the plane take off immediately, even arguing with crew members who offered them fruit plates due to their stated preference for non-meat food. One passenger requested to visit the cockpit, citing the child’s interest, a request that raised alarms in hindsight. Thorngren told TMZ, “I definitely think Flight 23 was the fifth plane.”

Adding to the intrigue, Mannello learned through another pilot that box cutters—similar to those used by the 9/11 hijackers—were found in the first-class seat pockets of an adjacent plane with a tail number nearly identical to Flight 23’s. He believes the weapons were mistakenly placed on the wrong aircraft, further suggesting a coordinated plot. The crew was interviewed extensively by the FBI the following day, with some taken to a Port Authority lineup to identify the passengers, but they received no follow-up information. TMZ reported that their requests for FBI records on Flight 23 went unanswered.

The FBI acknowledged an active investigation into a possible hijacking attempt on Flight 23 in 2023, according to Florida Bulldog, but has not released further details. The 9/11 Commission Report, published in 2004, makes no mention of United Flight 23, and no arrests related to the flight have been confirmed. Bob Kerrey, a former senator and 9/11 Commission member interviewed in the documentary, admitted he was unaware of a potential fifth plane at the time and noted the commission’s limited timeframe may have led to oversights.

Skeptics, however, caution against drawing firm conclusions. A Reddit thread on r/September11 criticized the documentary for sensationalism, pointing out that much of the evidence—such as the box cutters and reports of uniformed individuals running through the cabin—is secondhand or unverified. The term “Arabs” used by the crew has also raised concerns about racial profiling, with some online commentators suggesting the passengers’ behavior could be explained by stress or cultural misunderstandings. For instance, one Reddit user noted that “dark hair on a Middle Eastern woman is not uncommon,” challenging the assumption that the burqa-clad passenger was a man.

The documentary aligns with longstanding speculation about additional 9/11 targets. The 9/11 Commission reported that Al Qaeda’s Khalid Sheikh Mohammed initially planned to hijack ten planes, and box cutters were found on other grounded flights, including Delta and American Airlines planes, in the days following the attacks. An FBI report from 2022 linked a box cutter on a San Diego flight to a Saudi Arabian pilot previously under scrutiny, though no direct connection to Flight 23 was established.

TMZ’s claims of an FBI cover-up remain unproven, as the agency has not responded to requests for comment, and no official records confirm the allegations. Mannello expressed frustration over the lack of transparency, stating, “Nobody was forthcoming with what I think is a simple statement: ‘No these were innocent people on the flight, forget about it.’” The absence of Flight 23 from the 9/11 Commission Report and the FBI’s silence continue to fuel speculation, but without concrete evidence, the story remains one of the many unresolved mysteries of 9/11.