Having reached the summit of Aonach Beag at approximately 13:30, the party began to make its descent. Initially they descended NW to the col at GR 193720 then more steeply on a south westerly bearing in order to pick up the path running alongside the Allt Coire Guibhsachan with the intention of heading to the Upper Glen Nevis Car park. A few minutes after embarking on the steeper descent, the party made a short traverse north in order to gain an easier slope and avoid a blind descent directly below. At this point, the party had to make a short traverse (two steps) across a frozen stream. Using an ice-axe, steps were cut into a level section of the stream and the first walker crossed. As the second walker prepared to cross, he slipped on the slight embankment and slid down the frozen stream, despite trying to arrest his fall with his axe, he very rapidly picked up speed and was carried approximately 300m down the side of the mountain. The surviving member tried to make a phone call but had no signal. He then made his way down the mountain towards his partner whilst shouting for help. The calls for help were heard by another party on the hill. One walker made his way off the hill to contact the emergency services whilst the other remained with the stricken party. On reaching the fallen walker, checks were made but there was no sign of life. Light levels were now rapidly fading so the decision was made to cover the fallen walker with an emergency shelter and take a grid reference for the MRT. Within the hour, all other walkers were off the hill and the fallen walker was picked up by rescue helicopter 951. It was then confirmed that the walker had died of fatal injuries.