Abstract: Employee #1 was instructed to climb the derrick of an oil drilling rig and retrieve a drilling line. Before climbing the derrick, he was given a safety belt and lanyard and instructed in their use. A coworker accompanied Employee #1 to a position on the derrick across from the monkey board. The employee apparently unlatched his lanyard so he could move to the center of the rig mast and pull slack in the boom line. While pulling the line, Employee #1 lost his footing and fell approximately 95 ft to the drilling floor. He was killed. At the time of the accident, Employee #1 had worked less than 10 days on the job.