As a back country snowmobiler myself, I feel the need to reply. We're not all this oblivious. There are some back country rules that may have helped in this situation, and a lot of the spectators were probably unaware of the unwritten rules of back country snowmobiling. They are: 1. one at a time on the hill 2. watch from a safe viewing area.* (obviously not followed) 3. pay attention to the hill. 4. check out the avalanche advisory for the day and ride accordingly.
There are more, but the obvious conclusion is that the veiwing spectators missed 2 to 4 of the above precautions. Group think, nice weather, an event that was anticipated with relish, and lack of common sense seemed to have ruled the day, again... All of us who recreate in the out doors have to establish our own set of precautions that they live by, or NOT. Some will try to regulate our activities, and I always am against the Nanny state trying to legislate my safety. Dying is just one of the many fates that await us all, and it should be up to each individual, (or his or her parent/guardian) to determine the amount of risk they are willing to accept.
I do pray for the victims of the accident and their families.