I work for the Department of Transportation, and during the winter, I am assigned to plow snow in little cottonwood canyon. We usually don't go up at night, but there was a party at Snowbird, and I was told to go bring the partiers down at 10 PM. It was an absolute blizzard, and on my way back down, I lost all traction, and completely lost control of my truck. I began to fishtail really hard, and pick up speed. I was trying everything, I tried lifting my headplow, my wing plow, putting them down, hitting the engine brake, ect, but nothing seemed to pull me out. I was nearing an area where the Left side drops off a cliff, and thought for sure I was going over the edge. I put both my plows down, and tightened my seatbelt, and somehow, was able to angle myself so that I crashed into the mountain on the right side. I hit very hard, but didn't hurt myself. Anyways, it was freakin scary, and I'm glad I'm alive. The next time up/down wasn't quite as crazy as that one was.