Abstract: On October 29, 2005, Employee #1 was using a power washer to clean the substructure and BOP stack of a land gas well drilling rig. Employee #1 was positioned beneath the drilling rig floor on a catwalk. The catwalk surrounded the top of the BOP stack and rotary head within the substructure area. While doing the cleaning work, Employee #1 was utilizing a retractable lanyard personal fall arrest system. While working near the rotary head, Employee #1's fall arrest lanyard became entangled in the rotating machinery. The lanyard drew Employee #1 up tightly against the drill string as the machinery continued to rotate. Employee #1 was asphyxiated. A coworker, who was making periodic checks on Employee #1's cleaning progress, found him attached to and rotating with the drill string. The drill string was rotating at approximately 45 rpm at the time. The interval between the prior progress check and finding that the incident had occurred was approximately five minutes.