Abstract: Employee #1 had just assembled his repel system so that he could climb a tree. Employee #1 donned his safety harness and seat, and hastily tied his repelling line onto his safety line with two half hitches and a tail that was too short. As Employee #1 was moving around in the tree, the tail of the half hitches worked loose causing the half hitches to loosen. It was raining outside, and as Employee #1 stepped from one branch to another, his foot slipped on a wet branch. As Employee #1 fell the knots in his safety lanyard became undone, causing him to fall approximately 25 ft to the ground. Employee #1 injuries did not require hospitalization.