This sport is called "speedflying"

It combines the alpine and aerial elements of skiing and parasailing.

Speed Flying is a new winter sport created by paraglider pilots and skydivers looking for a new sensation and to create a link between gliding by ski and gliding through the air... As it's an extreme sport in the same league as Skydiving and BASE jumping etc. it is also very dangerous with a high risk of injury or even death. Wings can reach speeds in excess of 100km/h in the hands of the top Speed Flyers but normally are flown between 35 & 70 km/h and unlike Paragliding you don't have a reserve/safety parachute if anything goes wrong.

Enthusiasts have descended the Eiger in this fashion (video here).  Conventional ski clothing is worn, but one would think that a first-time participant might choose brown pants...