I ran across this short video from the NY Post this afternoon. I was intrigued enough to look for more info.

TMZ:

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.

From Adam Fitzgerald/Medium.com:

Meanwhile at JFK Airport, United Airlines Flight 23 a flight scheduled to depart to Los Angeles (LAX) at 8:30am. However it was late in pushing back from the gate.

Flight 23 captains, Carol Timmons and Tom Manello have heard a report over their radio that a plane has flown into the World Trade Center. They then receive an ACARS message, An ACARDS message is a digital datalink system for transmission of short messages between aircraft and ground stations via airband radio or satellite. The message is from Ed Ballinger,

“We have gone to heightened security. Do not open cockpit doors. Secure the cockpit.”

According to Lynn Spencer, author of “Touching History: The Untold story of the drama that unfolded from the skies on 9/11.”

Timmons starts barricading the cockpit door with their suitcases while Mannello grabs the crash ax for protection. Mannello calls the plane’s lead flight attendant to inform her of the threat, and tells her not to open the cockpit door under any circumstances. Soon afterwards, she calls back and informs him:

“We [the plane’s flight attendants] just think you should know this because we think it is unusual. We have four young Arab men sitting in first class this morning.”

Minutes later, the pilots receive a radio message from ground control, announcing, “All aircraft, be advised that the airport is now closed.” A subsequent message announces the airport is being evacuated. Mannello decides to move his aircraft back to the terminal. Soon after the flight attendant tells the passengers that the flight has been cancelled, the Arab men become abruptly agitated and the argument becomes so heated that she called airport security to the gate.

When the plane doors opened to let the passengers leave, the Arab males hurriedly left. Investigators will interview the plane’s crew nearly half a dozen times. But no information about the suspicious Arab passengers is ever released to the public.

Authorities will later check the men’s unclaimed baggage and find box-cutters, copies of the Koran, and al-Qaeda instruction sheets. On September 14, it is reported that investigators believe at least one of these passengers was among a number of individuals taken into custody at JFK and LaGuardia Airports the previous day. On September 13, New York authorities take into custody ten people of Middle Eastern descent at JFK International and LaGuardia Airports, reportedly fearing they intend to hijack aircraft and commit another suicidal terrorist attack on a US target.

More at link!