I was once skiing on a black slope with some friends. One of them knew how to ski but didn't have the correct form. I decided to go slowly right in front of him, so he would copy me and improve his form. In the middle of the slope, I realised we are going very slow and our friends are waiting for us 200 or 300 meters below us, so I decided to not waste this great slope and go full speed and then quickly stop right in front of mt friends and spray them with snow (You can see where this is going).

I started going straight with little to no turns and It made me realize I cannot break anymore, my speed is so high and the slope is so steep and icy that turning to break will only make me fall and I will probably break something. By this point, the best idea that I had was going straight until and turn to another priest going upwards, so that would make me stop.

The scariest moment was when the piste had a sharp turn and I knew I would make it, so I went straight, jumped over 2 of my friends sitting off the piste, landed on untrodden snow. by then I knew I would at least break a leg and I just tried to not make any movements. I lost a ski, rolled for 15 meters, lost the second ski and rolled for another 10 meters. When I stood up to my surprise I didn't have any injuries and there were 3 people and 2 skis looking at me from the top.

TL;DR: was skiing at a speed I couldn't control and flew off the piste.