Abstract: On May 1, 1991, Employees #1 and #2 were standing at the first floor level on a temporary platform that spanned the elevator shaft of a building under construction. The platform was made of two butted 13 ft by 9 in. by 2 in. wooden planks that were not secured against displacement. The platform was 30 ft above the bottom of the shaft, and no guardrails were provided. The employees were hoisting an acetylene cylinder to a coworker on the third floor by means of a rope and pulley equipped with a hook made of 3/8 in. rebar that was hooked into the safety cap. At the third floor the cylinder fell, struck the platform, and caused the employees to lose their balance and fall to the bottom of the shaft. Employee #1 was killed instantly and Employee #2 was hospitalized with a fractured skull.