A few years ago I had a Wingsuiter open up (his arm and leg wings) too early and he struck my horizontal stabilizer. The strike only slightly dented the sheet metal. However, it broke his right arm severely, which made it much more difficult for him to deploy his parachute and manipulate his toggles.
Luckily he landed safely. I waited to yell at him until after he returned to the DZ with his cast on and his pain pills in full effect.