United Flight 23 Pilot convinced of 9/11 Fifth Plane Theory, no coincidence

We talked to Tom Mannello Monday on “TMZ Live” about that fateful day, as well as a theory he’s fully on board with — namely that he and his United Flight 23 crew were targeted by terrorists on 9/11 … which he says they weren’t. fully believe until recently.

What changed his mind was a new documentary we produced that airs tonight on FOX — “TMZ Investigates 9/11: The Fifth Plane” (9:00 p.m. ET/PT, 8:00 p.m. CT) … which takes a deep dive into all the suspicious circumstances surrounding the activity on the plane due.

It’s a story the United crew hadn’t previously discussed publicly, and hearing the flight attendant’s perspective changes everything for Mannello.

As he explains to us, he was content to accept that everything that unfolded was just coincidence … but after we did some digging and reporting, he says he’s a believer.

There are several elements that point to United 23 being in the crosshairs of bad actors – including a group of suspicious passengers who were eager to get off the ground ASAP.

Another red flag … the fact that eyewitnesses saw uniformed people running through the cabin after the plane had been evacuated and locked down — this after official reports that the World Trade Center was under attack.

Then the FBI discovered a mysteriously opened hatch on the plane.

Agents also interviewed all of the passengers of flight 23 afterwards … plus box cutters were found on an adjacent flight – all of which is more than enough for Mannello to buy into the idea that they were next. He says that for years he did not accept it because of the apparent inactivity of the feds.