Abstract: Employee #1, a 20-year-old warehouseman, and a coworker were filling a 6,000-gallon #2 fuel oil tank from the top. They had finished loading 1,621 gallons into the tank and as Employee #1 was on his knees, backing off the top of the tank, preparing to descend. He disconnected the lanyard attached to his positioning belt and lowered his right foot over the edge of the tank, trying to feel for the top rung of the extension ladder. When he put his weight on the right side of the rung, the ladder shifted to his right. The coworker, who was manning the ladder from the ground, tried to stabilize it when Employee #1 shifted to his left and fell approximately 17 ft onto the piping and concrete floor at the base of the tank. he sustained multiple contusions, for which he was hospitalized.