[ericd]

That's the forward component of the velocity vs the component that's normal to the ground, though - the collision with the Earth is much lower speed than the lateral motion (sliding along the surface after the fall). If you're skiing aggressively, you're frequently quite close to the ground, and a fall is frequently where you end up grazing it because you lean further than the centripital force can maintain. You fall a much shorter distance toward the Earth than a timid skier does.

If you're skiing at the level I'm talking about, falls are probably not that frequent, though.

In my earlier comment I was talking more about the explosive vertical compression-expansion cycle that characterizes skiing really hard with very tight turns on short radius skis. Those are much less violent than hitting a lineman though.