Channel/Blowdown Duffey

Skier 1 ski cut slope to safe area, no result but could feel windslab, ski cut again to another safe area no result. I dropped in did a few turns then cut into area where skier 1 was, but just below his second ski cut. I wasn't far enough off the slope, and it broke loose between myself and skier 1. Took me apprx 300 to 400 mtrs downslope. Managed to keep board out in front of me, and eventually was able to dig my board into the bed surface and got pushed to the flank. Rest of slide continued onto the bottom of the path. Slab depth at top was apprx 10 inches, and it propagated across the slope. Called out that I was okay, friends were already on their way ready to search. Lessons learned for sure that day.