Abstract: At 5:15 p.m. on February 20, 1985, Employee #1 was installing sheets of plywood as decking material on the fifth floor center. The floor is constructed in separate "tables" that are 4 ft apart, usually at the column line. The decking is typically constructed with a 2 by 4 on the metal joist, which supports a 4 in. by 4 in. beam, which in turn supports the plywood. The 2 by 4 rug rail and the 4 by 4 beam had not yet been installed, and the plywood under Employee #1's foot gave away when he attempted to jump across the 4 ft opening between the east and west "tables." He fell from the fifth to the fourth floor decking, suffering a fractured left clavicle, head trauma, and a laceration behind his left ear. A 4 ft by 8 ft sheet of 3/4 in. plywood had been placed across the opening just 6 ft from the place of the fall. Employee #1 misjudged a hazardous situation.