Who can forget the images of that 69-year-old Kentucky doctor -- David Dao -- who was knocked out and then dragged off a United Airlines plane when he refused to give up his seat on the overbooked flight from Chicago O'Hare to Louisville? I know I can't. It's every flyer's nightmare.

Today, for the first time, David Dao spoke publicly about that nightmare.

This morning on the popular television show Good Morning America, Dao explained that when the video of his forceable removal from the United Airlines flight first went viral, he had no idea that it had. But, when he saw the video months later, his reaction was immediate:

Few months later, after I get my cell phone back, my iPhone back, the first reaction is, I just cried.

According to Dao, he had no idea that his refusal to give up the seat he had paid for would result in physical violence against him. Said Dao in this morning's interview:

They pulled me out of the seat and I said I didn't know anything. Until I wake up in the hospital and they try to fix me.

Previous reports say that United Airlines reached a confidential settlement with Dao to the tune of $140 million for the injuries he suffered, including a broken nose, a concussion, and broken teeth.

Said United CEO Oscar Munoz three days after the incident:

This will never happen again. We are not going to put a law enforcement official onto a plane to take them off...to remove a booked, paid, seated passenger. We can't do that.

For his part, Dao says that there's a silver lining in his terrible experience. He believes that the incident turned out to be a positive thing because it forced United Airlines to take a close look at its policies and change them for the better. Said Dao in the interview, "Everything happens with a reason."

In a statement to ABC News, United said this about the aftermath of the incident:

This year, we are focused more than ever on our commitment to our customers, looking at every aspect of our business to ensure that we keep their best interests at the center of everything that we do. As our CEO Oscar Munoz has said, we at United never want anyone in the United family to forget the experience of Flight 3411. It makes us a better airline, a more caring company and a stronger team.