Who, where and how long, if you don't mind sharing?
Forrest and I were on the South Seas in October 1989 (it's on El Cap, it was rated 5.10 A5 when we did it - one of it's first 10 ascents).
He disintegrated a dowel ladder and pulled some heads on the pitch above the dihedral just above where South Seas joins The Pacific Ocean Wall. From a move or two below the belay, he ended up hanging in space 20' below me. And he did it on my brand new rope. It was about a 110 foot fall.
This was also all air, and no-one was hurt, but it sure scared the sh#t out of both of us (the holy, holy sh#t to be more precise). When he fell I couldn't see him. Then he came into sight, still falling. Pieces ripped out so fast that it sounded like someone shooting off a .22 caliber rifle on semiautomatic as fast as they could. Near as we could tell, his wife was in El Cap Meadow watching just before he fell. She didn't see the actual event though. By the time he stopped I'd concluded that he was going to go all the way to the ground 18 pitches lower.
The next day I had to lead the dowel ladder above there (by then on our seventh day on the route). I was so scared that I had to tell myself that I was probably going to die and just accept that it was so before I could make myself start.
The only other time that I had to just accept that I was going to die and go on anyway was ten years later (1999) when I went back to Wet Denim Daydream with Dennis Erik's help. I came so close to backing off on that route; Dennis was totally patient and just gave me mild encouragement and waited. I've never heard his version of doing that route, but I've always been grateful to him for his understanding and patience.
After his fall on the South Seas, Forrest started to give up climbing. I'm not sure it was because of this fall, he also became a father and got interested in (I detest the very word) kayaking.
I have also probably held the second longest fall of anyone on here too (it's not me either, I swear; I don't make them fall).