OBERLIN, Ohio (WJW)– The urgent calls from air traffic control are still haunting two decades later.

Air traffic controllers at the FAA’s Cleveland center in Oberlin tried to reach a hijacked plane on Sept. 11, 2001.

“You can’t live through that and not have some pretty strong memories of it,” said Bill Keaton, air traffic controller on Sept. 11.

Now retired, Keaton still remembers first learning of the attacks on the World Trade Center, then being alerted to a possible threat in the skies over Northeast Ohio.

“Someone had forced a data block to my scope, United 93. Someone ran up behind me, said, “Don’t let anyone within 20 miles of that airplane” and then ran out,” he said.

United Flight 93, from Newark to San Francisco, changed course as terrorists hijacked the plane near Cleveland. They switched off the plane’s transponder so Keaton could only track it by radar.

“All we had was a location. We had no altitude information, no speed information,” he said. “There’s only one reason to turn a transponder off.”

His attempts to reach the plane went unanswered.

“It basically is going the wrong way on an airway that comes out of the Washington area,” Keaton said. “It’s pretty obvious at that point it’s going after the White House, the Capitol, somewhere down there.”

As Keaton was tracking Flight 93 on radar in Oberlin, passengers on board the plane were rushing the cockpit after learning through cell phone calls that other hijacked planes were crashed into buildings.

The plane disappeared from Keaton’s screen. A pilot in a nearby plane confirmed to him that smoke was rising near Shanksville, Pennsylvania. There were no survivors.

“It’s your job as an air traffic controller to keep planes safe. And you just watch one disappear from your radar scope and you know what that means,” Keaton said. The gravity of the day set in as the FAA closed the nation’s airspace.

“You knew at that point, you were in a historic, life-changing event,” Keaton said.