CLEVELAND, Ohio-- "Tuesday, September 11, 2001 dawned temperate and nearly cloudless in the eastern United States."
So begins the official 9/11 Commission report on the terrorist attacks that killed 3,000 people - and changed the world.
On Sunday, the nation will pause to commemorate 15 years since that fateful day.
As we all know, Al Qaeda terrorists hijacked four commercial planes that day, slamming two into the World Trade Center's Twin Towers in New York, and the third into the Pentagon just outside Washington D.C.
The fourth plane, United 93, was flying near Cleveland when the hijackers took control and turned it back towards the nation's capitol.
Flight 93 was in the air space of the FAA's Air Traffic Control Center in Oberlin (referred to as the "Cleveland Center").
"The unusual thing about Flight 93 was that it was coming towards my airspace, but there was no altitude information," said Bill Keaton, one of the controllers monitoring that plane on 9/11.
Keaton spoke to us a few years ago on an earlier 9/11 anniversary.
"He was on a track known as J5-18," Keaton remembered, "and it's basically an airway restricted to planes leaving Washington D.C. going to the northwest."
But the terrorists were flying the plane the wrong way in that corridor - back towards Washington D.C.
As we now know, heroic passengers attempted to retake control of Flight 93, after learning that other terrorists had already slammed planes into buildings earlier that morning.
In the struggle, the terrorists crashed the plane into the ground in Shanksville, Pennsylvania, killing everyone aboard.
Bill Keaton had watched Flight 93 disappear from his radar screen.
"You feel helpless," he recalled, "because it's your job to keep the airways safe."
In the days and weeks after 9/11, there were calls for Americans to "never forget."
15 years later, nobody has.