Abstract: At approximately 8:55 a.m. on February 25, 1991, Employee #1 was inside the hoist tower of a dual car personnel/material hoist. He was affixing a 4 by 8 ft sheet of plywood over an opening in the south side of the wire mesh cage around the hoist tower. The south car was locked out but the north car was in operation. Employee #1 climbed down and was on the concrete between the two cars but near the counterweights for both of them. The north car was going up and Employee #1 failed to notice that its counterweight was coming down until it struck him in the back just below the neck and pushed him down. Employee #1 called to his helper, who was outside the tower cage; the helper went to the main power disconnect south of the tower and shut off the power. Employee #1 sustained a broken back and broken right leg as well as various contusions and abrasions. Although the foreman had instructed him to cover the hoist tower opening from the outside, Employee #1 thought it could best be done from the inside. The main causal factor appears to have been employee conduct.