A United pilot scheduled to fly on 9/11 says he lived in denial for years about the possibility hijackers targeted his plane that day ... but he's more convinced than ever now.
We talked to Tom Mannello Monday on "TMZ Live" about that fateful day, as well as a theory he's fully onboard with -- namely, that he and his crew from United Flight 23 were targeted by terrorists on Sept. 11 ... something he says didn't fully believe until very recently.
What changed his mind was a new documentary we produced that's airing tonight on FOX -- "TMZ Investigates 9/11: The Fifth Plane" (9 PM ET/PT, 8PM CT) ... which does a deep dive into all the suspicious circumstances surrounding the activity on the grounded flight.
It's a story the United crew hadn't previously discussed publicly, and hearing the perspective of the flight attendants is changing everything for Mannello.
As he explains to us, he was content to accept everything that unfolded was mere 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 persons running through the cabin after the plane had been evacuated and locked -- this after official word the World Trade Center was under attack.
Then the FBI discovered a mysteriously opened hatch on the plane.
Agents also interviewed all of flight 23's attendants afterward ... plus, box cutters were found in an adjacent plane -- and all of that is more than enough for Mannello to buy into the notion they were next. He says, for years, he didn't accept it due to seeming inactivity from the feds.
At this point, though, he says there's simply too much evidence not to accept the obvious. And yet, despite this, TM explains why he continued to fly in the aftermath ... unlike the others, who were so shaken up they never flew professionally again.