Abstract: Employee #1 was instructed to keep a tower crane's running block from damaging the edge of the ninth-level concrete balcony while another crew was placing a precast concrete pier under the seventh-level balcony. He was using a full-body harness and his lanyard was attached to the vertical center safety line. He was also in radio communication with the signalman and the crane operator. Three safety lines were anchored to the window washer's anchors at the top the roof: two were dropped to either side of the balcony and one was dropped about center with the balcony. The pier was brought in by the crane near the center of the balcony. The signalman directed the crane's movement in placing the pier. As the crane block approached the balcony, Employee #1 braced himself against the wall. He was pushing the block away from the balcony's edge when his safety line became entwined with crane's fall line as it moved up and over. The safety line was snared in the block's sheave, stopping the crane and leaving Employee #1 suspended about 70 ft above the courtyard. He tried to remove his lanyard from the safety line and was calling by radio for an emergency stop when his back struck the bottom of the tenth-level balcony. He sustained a fractured vertebra, for which he was hospitalized.