Christopher Tucker, an air traffic controller in New York City on the morning of September 11, 2001, said the day started off just like any other, but quickly became the most unforgettable of his long career. 

Tucker, an air traffic controller for 13 years prior to 9/11, told Fox News Digital in an interview that he was working at the New York Air Route Traffic Control Center on Long Island on the morning of 9/11, and that before the attack the day was "remarkably beautiful."

"I’m not the person to notice things like that and I stopped to look at the sky," Tucker said. "It was a very blue, crystaline sky. The bastards couldn’t have picked a better day. Everyone was commenting on how nice the city looked, how clear it was."

The tranquility in the air turned to concern after Tucker was alerted to a possible hijacking situation when American Airlines Flight 11 turned off its transponder and turned south over the Hudson River towards New York City. 

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American flag flies in front of air traffic control tower in New York

Ronkonkoma, N.Y.: The FAA control tower at Long Island MacArthur Airport in Ronkonkoma, New York on March 25, 2021.  ((Photo by Steve Pfost/Newsday RM via Getty Images))

"We could still see what we believed was AA11 heading south toward New York, but we had no idea what its altitude was," Tucker said. "A few moments later an aircraft on my frequency mentioned that the south tower was on fire and there was a lot of smoke. After listening to the tapes later, one of the pilots had said ‘Maybe it’s that American you guys are looking for,’ but I didn’t remember hearing that or even thinking that during the time. All we knew for sure was that he was no longer on the radar."

Tucker recalled that at the same time the American Airlines flight situation was unfolding, suspicious information related to United Airlines Flight 175 was being relayed to his control tower. 

"All eyes were focused on AA11," Tucker said. "As we tried to figure out what was going on, we noticed that the computer track for United 175 was showing up as an ‘intruder’ because someone on the flight deck had changed the transponder code to a code that the computer couldn't identify. I believe that was the terrorists. UA climbed and then began descending and turning left to the south towards New York City."

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Photo of former air traffic controller Chris Tucker

Former air traffic controller Chris Tucker (Christopher Tucker)

Tucker says he was becoming "increasingly concerned" about the two aircraft and a possible collision with other flights that were in the air. 

"My job is to keep airplanes from colliding," Tucker said. "I had issued a traffic call to both of my climbing aircraft: ‘Delta 2315 and US Air 542, traffic, one o'clock, one five miles turning southeast and descending, we believe it is a hijack and we don't know his intentions.’"

Tucker explained at that moment he had "no idea" what the intruder was going to do and he and his coworkers sat at their desks "completely aghast."

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"We thought maybe he was trying for Newark or maybe LaGuardia," Tucker said. "But deep down we knew. They were going to crash the plane into the city. They were pointed right at lower Manhattan. Once they were off the radar, we knew we had just watched a commercial airliner deliberately crash into New York City with who knows how many people onboard and on the ground."

Tucker told Fox News Digital that a man working next to him had a best friend who was working in the World Trade Center.

"He knew his friend was dead, tears were streaming out of his face while he was working traffic," Tucker said. "The girl next to me was crying, I tried not to because I was talking to airplanes. When we became aware of what was going on, we went from being really, really sad and upset to wanting blood, like a switch we became very angry."

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World Trade Center collapses on 9/11

394261 12: A fiery blasts rocks the World Trade Center after being hit by two planes September 11, 2001 in New York City. (Photo by Spencer Platt/Getty Images) (Spencer Platt/Getty Images)

One person in the room said that he would sign up to serve in the military "right now" if he could, Tucker remembered. 

"Just get them in the air now," Tucker says he remembers a supervisor screaming, presumably talking about scrambling fighter jets

"We had no experience with this," Tucker said. "It was unheard of in the U.S. for a hijacking to take place."

Tucker says he took two weeks off of work after the attack and spent a lot of time outside and speaking to a psychologist to try and process what had happened.

After returning to work, Tucker says it took time to readjust and the first couple of minutes back on the job were "weird" and "didn't feel like I had my feet under me."

"Everyone said they felt like that," Tucker said. 

Aerial view of the World Trade Center rubble on 9/11

An aerial view of the NYC Custom house and surrounding area.  (HUM Images/Universal Images Group via Getty Images)

Tucker retired from his position as an air traffic controller in 2014.

"One of the things I think about it is that it [hijackings] will never happen again in the U.S.," Tucker said. "It can’t happen because the people on the plane won’t let it happen — the passengers."

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Tucker told Fox News Digital that the first couple of years after the attack were "painful" and that he still hasn't seen the movie United 93, which features a character that plays him. 

"I still haven’t seen the film and it’s 21 years later," Tucker said. "I haven’t been to the memorial, either. Whenever I’d listen to those tapes, it just pulls at your heartstrings."