September 11, 2001, attack on the World Trade Center
September 11, 2001, attack on the World Trade CenterREUTERS/Sean Adair/File

The captain of a United Airlines flight that was supposed to take off on the morning of September 11, 2001 told TMZ that he believes his airplane was supposed to be hijacked by the terrorists to be used as the fifth plane in the attacks against the twin towers and federal buildings.

“There is a good chance that somebody was plotting to try to use our airplane as a weapon of mass destruction,” pilot Tom Mannello said.

He made the startling admission as part of a six month investigation that culminated in the Fox special, “TMZ Investigates: 9/11: The Fifth Plane.”

The program’s investigators spent months looking into the suspicious activities surrounding the Boeing 767, Flight 23, that was scheduled to take off from JFK Airport at 9 a.m., heading to Los Angeles.

Manello described finding out that two box cutters had been discovered in first class seat pockets of a plane parked next to his, whose tail number was only one digit different.

“If somebody was on the ground cooperating with them, they just simply made a mistake and put the box cutters on the wrong airplane,” Mannello said

In the hour-long show, there are also interviews with flight attendants on Flight 23 who talk about four suspicious passengers in first class: two men, a baby, and someone dressed in a hijab who the flight crew thought was a man dressed as a woman. There was also a man in business class covered in sweat.

“It was odd because it was 8 o’clock in the morning, and airplanes are cold anyway, but it was a cool morning,” Sandy Thorngren, one of the flight attendants, recalled.

The flight crew’s suspicions are also based on the odd behavior by the first class passengers, who told a flight attendant identified as “Deborah” that they didn’t eat meat, and then demanded to take off without receiving their fruit plates.

“I could hear them say, ‘We do not want to eat, we don’t need food. We want to take off. We don’t need food. We just want to go,'” Thorngren said.

During the 9/11 attacks, four planes were hijacked and crashed by 19 terrorists: two into the World Trade Center towers, one into the Pentagon, and a fourth into a field in Pennsylvania after passengers prevented it from being flown into a DC federal government building.

According to the special, 20 minutes after passengers and the crew disembarked from Flight 23, witnesses on the tarmac saw people in uniforms running through the passenger cabin.

Authorities investigated and found that a floor hatch had been opened which led from the cabin to the plane’s belly.

The documentary postulated that the two people were looking for the box cutters mistakenly hidden on the other plane.

It also revealed that the FBI interviewed the flight crew the next day and they had to view a lineup at the Port Authority to access if they could identify the four suspicious passengers from first class.

Former Rep. Carolyn Maloney (D-NY) was interviewed in the doc, telling TMZ that the matter needs to be examined by Congress.

“I’m deeply concerned that it could be the fifth plane,” she said. “I would say that the Intelligence Committee and Congress should look at the intelligence reports that came out from this investigation that took place.”