Abstract: A line-clearance tree trimmer was using an aerial lift mounted on an International 1600 truck, pruning trees from an overhead power line. The outriggers on the aerial lift were down, and the right outrigger was on an 850-millimeter by 380-millimeter by 75-millimeter block of wood. The truck was facing down a slope of about 10 to 15 degrees. The emergency brake was set, and the truck was chocked. The tree trimmer had just finished trimming a tree and, with the boom extended, he lowered himself to get a cut branch out of the tree. As he stopped, the truck overturned, and the employee fell to the ground with the boom. The employee was hospitalized for injuries sustained in the fall.