In reply to climbwhenready:
> It was this route that made me think of it, but I was asking generally.
In that case, this is from the Forces chapter on www.multipitchclimbing.com
Another place where it is important to consider angles is if the protection is off to the side and a swing might end with the leader or second hitting something, usually the opposing wall of a corner. From high school physics we know that if the climber falls a distance h then their potential energy mgh will have all been converted into kinetic energy ½mv2 at the base of the fall. This is true whether the drop is a straight line or a swing. This means that a 2m (6ft) swing into a corner (with the protection at the same height as the climber) is the same as a 2m fall onto a ledge. A leader will try to do their best not to drop the second 2m onto a ledge, so they should try to not allow them to smash into a corner at the same speed. Often this situation can be avoided by the use of a second rope, or not placing protection at the base of a corner if using only one rope. The mental picture that probably needs to be encouraged is one of “corner equals ledge”.
A swing can easily be even more serious than a straight fall of a similar terminal speed. In a vertical fall onto a ledge you will hopefully land on your feet and your legs will bend to absorb the impact. In a swing the climber might impact the wall side-on, not feet first. This can lead to serious injuries even with small falls. (How would any of us fancy being dropped 2m horizontally onto a stone floor onto our ribs?) Accident data shows that a surprising number of climbing accidents are of this type, and possibly indicate that climbers don’t try take side falls as seriously as they should.