(FOX 46 CHARLOTTE) – Four hijacked planes took over the sky above America on September 11th. Watching everything unfold from in front of a radarscope were thousands of air traffic controllers.

9/11 was a day every contingency came together in tragic cross-country harmony for controllers, including Mark Di Palmo.

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“Exactly what was happening with the trade center, when the first American [jet] had disappeared… there was talk when I had just walked in that it was a small plane that took off out of Duchess County and came up the Hudson River,” said DiPalmo.

At New York Center, DiPalmo was on the floor, acting in his union role helping coordinate with management that morning.

He says the full picture of what the attacks entailed wasn’t fully realized.

“Trying to talk to the command center saying that we need to stop everything going into and out of New York.”

His first day on the job, FAA National Operations Manager Ben Sliney knew that getting 3-million square miles of airspace under control was going to be a challenge.

“As the morning wore on — this was a situation that was being motivated or run by people with a seriously harmful agenda. The second event which was my ordering all aircraft to land at the nearest airport. That was born out of the crash of American 77 into the Pentagon.”

Back at New York Center on Long Island — DiPalmo was on point as other controllers cleared the most congested airspace in the country. All while knowing their family and friends could have been killed at the World Trade Center.

“Most of the people being New York natives, knew somebody that either worked at the Trade Center or a stones-throw [away]. Doing what had to be done that day — that amazing feat that they did, they were able to compartmentalize and shut off… ‘how’s my brother doing, he’s down there’ … best friends, cousins, neighbors.”

Ben Sliney retired from the FAA in 2003. He says the events of September 11th mark a time in history highlighted by triumphant moments of teamwork underscored by terror. A day we have to keep talking about for the sake of the thousands of Americans lost.

“I think it pays tribute to people like Betty Ong who took it upon themselves to act… I say, outside the scope of their duties. To try and bring the situation they were in — under control.”