Originally Posted by Tog
The "look over the shoulder" when changing lanes at 65mph on the highway is not only practical but recommended and safer. It's a glance. to check your blind spot. On snow you're not going to run in into people simply by looking to see who is uphill as you cut across that hill.
But the issue is your use of "ahead". You say:
"If you're in a crowd, looking over your shoulder endangers those who are ahead of you for the entire time you're looking over your shoulder."
When you're cutting across, you're no longer going downhill much, ahead is now the other side of the trail. You're not descending downhill at a rate of speed that's going to cause you to mow down skiers simply by glancing over the shoulder.
How about this:
Suppose Mr. Grey is not a skier but a snowboarder whose on heel side cutting across facing downhill. Same exact path, same collision.
Probably a good percentage of those blaming Red would now blame the snowboarder for cutting across the slope blind.
I suspect people would say Grey guy has now, as you wrote about Red, "voluntarily put himself into a dangerous position and stayed there for a significant period of time."
Again, the analogies fall short.
On the highway, you're driving on a fairly straight road with marked lanes in a vehicle that has mirrors and is controlled with a steering wheel rather than your body weight and balance. So, before you look over your shoulder, you already have a good idea of what's going on behind you, you know which specific area you need to check when you look over, and you know that turning your head isn't going to affect your balance and cause the car to veer off course.
On skis, there are no marked lanes, you're not usually travelling in a straight line, and you have to check a lot more terrain when you turn your head because you don't have mirrors. So, the movements of those in front of you are less predictable and it takes you longer to see everything you need to see when you turn your head. Also for some, significant movement of the head affects their balance, which then makes it harder to control their skis.
As for looking uphill while cutting across the hill rather than before, what's the point of that? If you expect people cutting across the hill to be responsible for avoiding those above them, then surely they would have to check before they start cutting across. Otherwise, they've made their move before checking that it's safe. But if they check before they make their move, it means they're not watching what's in front of them.
As for the snowboarder hypothetical, I would still blame the red guy and would consider his actions even more dangerous. Cruising on a boarder's heel side is like skiing directly behind a skier. If you're not watching where he/she is going, then you're just as responsible for a collision as you would be if you slammed into the back of a skier who slowed down/stopped directly ahead of you.
If you expect boarders to turn completely around to check uphill and make sure no one is going to slam into the back of them, then I guess you expect skiers to turn completely around and ski switch for a couple of seconds every time they want to stop. I mean, surely they should have to check to make sure no one is going to slam into the back of them.