I've seen videos of mountain climbers stranded on a ledge. It's a horrible predicament. You can't go up and you can't go down and cellphone doesn't work.
When I was much younger I did a bit of mountain climbing and the golden rule was to stay as far apart as possible so if one falls into a crevice or over the side, the others won't.
P.S. There was a recent story from out West that 3 (or 4 or something like that) all fell into a crevice and died. They, obviously, were climbing too close together so when one fell they all fell and died.