I agree this is a bit of a stretch as an example, but yes people do drop stuff on climbers. Still an interesting story and maybe a good sign that even the smallest objects (drones or boulders) can lead to a runaway effect on a cliff. Thankfully though, it does have to be a "one in a million" coincidence to hurt someone.

http://www.outsideonline.com/outdoor-adventure/climbing/rock...