The same thing happened to my friend on our last trip.
He took a hard fall, and by the time he got to the bottom he realized the camera wasn't on the helmet anymore. We went back up and did another run, and searched the area where he fell with no luck.
Got back down and talked to one of the lift attendants and someone ended up turning it in. When we got back to the hotel we plugged it in and took a look at the video. Camera was on the entire time, we have it all on video from the fall until we retrieved it. Was kinda cool.