Worth asking why though. The group were described as experienced winter walkers, although this must have been short as they seemed to be in their early twenties. They broke two rules. Don't go on the mountain immediately after a heavy snow fall. And especially don't go on to a lee slope , that is, the opposite slope from which the wind is dumping the snow is blowing as the snow will be unstable. Accord to a report I saw yesterday on BBC news, this is exactly what they did. No amount of 'right gear' would help. It is many years since I was on Bidean but I remember a steep snow slope going up to the ridge from the head of the hidden valley. I would think this is the likely site of the fall. When we climbed it, it was Easter and the snow was consolidated and safe.