In rock climbing, the largest number of deaths happens from rappelling, for a variety of proposed reasons. I think it’s because people sometimes don’t take it seriously enough. If something goes wrong, you have a long, long drop and you are NOT belayed.
From Wiki on Mogadishu
>>During the operation’s first moments, Ranger PFC Todd Blackburn, from Chalk Four, fell while fast-roping from his Black Hawk Super 6-7 while it was hovering 70 feet (21 m) above the streets. The film Black Hawk Down shows that he slipped when the helicopter was forced to take evasive maneuvers to avoid an incoming RPG fired from a nearby rooftop, although, according to Bowden, video does not show the helicopter moving. Blackburn suffered an injury to his head and back of his neck and required evacuation by SGT Jeff Struecker’s column of three Humvees