Falling down the Leuthold Couloir on the Grand Teton - nearly. I was crossing a tracked snow patch above it aftercompleting the Upper Exum, and the slope was mild, so my partner initially balked at my suggesting he put me on belay (I was doing the crossing in rock climbing shoes). I made this decision after considering the runout, regardless of how trivial the slope seemed.
It turns out the snow was a thin layer of slushy snow on top of blue alpine ice, and when I was halfway across, the snow slide and I went down with it. The belay caught me after I fell about 50 ft, and by then I was already on a 45 degree slope and had to skitter around before I could swing myself over to rock on the side.
Breaking off a cornice, and falling 1,000 ft into an avalanche slide - OK, now when climbing on a snowy ridge, regardless of how trivial the route is, or how unlikely you think the ridge is to form cornices,or how experienced you think the lead trailbreaker is, NEVER BLINDLY FOLLOW THE LEADER!
Nearly Losing my head on Clyde Minaret - We were descending the Rock Route and on the beginning of our downclimb off the ridge, we relaxed our team's spacing/coordination. One guy lagged behind slightly while the rest of us were close enough to downclimb a descending traverse to avoid each others' fall line. When the last guy in the group came down, he stayed high on a ridge and suddenly came over the crest right above me. He accidentally knocked off a microwave-sized block. I was far enough away for the rock to be airborne, but too close to hear him shout rock - I heard the rock dislodge and lept to the side just as it whizzed past my head and bounced off the next ledge down, somewhere high on this face. If it didn't take my head off, it certainly would have knocked me off the route!
Falling 15 ft in steep class 4 terrain - I was climbing Basin Mountain and had climbed up on a chockstone that I had rigorously check (thumped it around pretty hard, up, down, and sideways, with no movement and a solid-sounding thud). I was standing on it for about 30 seconds deciding which way to go when it blew out and I fell 15 ft onto a ledge. Luckily I leaned into the chimney as I fell, so I didn't bounce off the ledge.
Getting caught in a major rockslide - I was skating down the very steep and loose class 2 SE face of Mt Wallace. Suddenly all of the scree around me started moving with me. Then some larger boulders slid onto my left leg and pinch it into the flowing sand, which was accelerating. I grabbed a larger stationary block as I slid by, pulling myself out from the rocks holding me down. Some of these larger rocks then picked up enough speed to ricochet, causing a large part of the face to slide. It lasted for several minutes, visibility went to 0 from the dust cloud that billowed up, and people in the next canyon over could hear the slide and see the dust plume.
And then there are the smaller cases:
- Getting caught in a lightning storm on a high-altitude plateau
- Jamming in a crack that turned out to be a refrigerator-sized detached block (it was night and I was following!) that came off as I was transitioning out of it
- Punching into a moat which almost made me trip and fall over backward on a 50 degree snow slope with a cliff below. Instead I managed catch myself and hold myself into the slope as I slid in up to my chest.