My wife and I, both 28, were climbing a popular multi-pitch sport route at the Goat Wall, Prime Rib of Goat (5.9), in the summer of 2012. A group had caught up to us, and we allowed them to pass at one of the generous ledges en route. Since this was a long climb, it was important to keep moving, and I started leading the next pitch about 10 to 20 feet below the second climber of the party that had just passed us.
I had passed the first or second bolt when I heard “ROCK!” At first I looked up, but thankfully I quickly turned my head back into the wall before a baseball-size rock came down and hit me directly on the helmet. It was enough of an impact that I was a bit fuzzy for a moment, but soon I was able to continue climbing. I had no ill effects, and I think the outcome would have been very different had I not been wearing a helmet.
Read the full report and analysis from Accidents in North American Mountaineering.