On July 14, 1999, three male ironworkers (the victims), ages 39, 40, and 52, died after falling approximately 300 feet to the ground when the suspended personnel platform they were occupying was struck by the uncontrolled load of a heavy-lift crane. The victims were working in windy conditions during the construction of a county sports stadium. The three ironworkers were suspended about 300 feet above the ground to observe the hoisting of a 450-ton roof section. The roof section had been hoisted to about 330 feet and transported over its connection location by the heavy-lift crane crew. As the roof section was being lowered into place, the heavy-lift crane began to tip over. The crane continued tipping, and the roof section collided with the personnel platform, knocking it and the victims to the ground. Fire department and emergency medical personnel were immediately notified and responded within 5 minutes. The victims were pronounced dead on site by the county medical examiner. NIOSH investigators concluded that to help prevent similar incidents, employers should: 1) implement specifically engineered lift plans for critical-lift hoisting operations. Such plans should be designed by registered professional engineers having specialized knowledge of critical lift operations and should be based on the following: (1) the rated capacity and operational limitations specified by the crane's load chart; (2) measured, as opposed to calculated, weights for the materials to be hoisted; (3) thorough studies of wind speed and its effect on the crane and hoisted load; and (4) consideration of the effects of ground conditions and dynamic forces on the crane's stability; 2) ensure that cranes and work areas are equipped with strategically located instruments to monitor wind velocity (speed and direction) at or near the elevation of hoisted loads; 3) ensure that suspended personnel platforms are not used during weather conditions which could endanger the hoisted workers; 4) consider alternative methods of observation when landing locations are not readily visible to ground-level observers during hoisting operations; 5) ensure that only personnel necessary to safely complete the lift are assigned as hoisted observers; 6) ensure that cranes are equipped with correctly calibrated instruments to accurately monitor all parameters affecting safe crane operation, additionally, designers and erectors should; 7) carefully evaluate worker risk when devising construction and hoisting methods for use during steel erection.