When learning to ski or ride its important to keep in mind that there are good ways to stop, problematic ways to stop, and one really bad way - collision. In the context of skiing a collision can be defined as one moving person striking violently against another person or a solid object.
According to Dr. Jasper Shealy, a professor at the Rochester Institute of Technology, the number of collisions accidents with other skiers or snowboarders accounts for only 6.4% of reported accidents so they are thankfully rare, but disproportionally serious. He calculated In the period between 1991 and 2005, 60% of fatalities were the result of a skier or snowboarder hitting a tree. Hitting a man-made object, such as lift towers, was the cause of 7.6% of the fatalities.His research also concludes that alpine skiers are three times more likely to be involved in a collision with other people than snowboarders.
Colorado law presumes that the uphill skier (or rider) is at fault in any collision, because the faster skier has a moral as well as legal obligation to avoid a skier below who may not be able to avoid him. All skiers and snowboarders, even first timers, also have a responsibility to exercise caution, to ski or ride within their ability, and to maintain control at all times. Part of being cautious is to stop in a place that is both safe for themselves and others and when starting downhill to look uphill and yield to skiers or riders already in motion.
Colliding with a tree can kill you but colliding with another person can create a law suit. Most laws covering skiing require individuals involved in a collision to stop at the scene, aid anyone injured, and to provide their full name, address and identification. If they become involved, ski patrol will usually compile a comprehensive report about the nature, location, and causes of the collision which can be used as evidence in litigation.
Risk is an inherent part of skiing and risk is related to uncertainty. Conditions can be highly variable so there may be a circumstance when a collision is the preferable alternative, but I can not think of one.