Abstract: Employee #1 and coworkers were working in a seven-story building that was being renovated. They were installing a 2 ft by 4 ft metal air duct up through 8 ft by 16 ft in-line floor openings that had not been walled in. The duct sections were raised up for installation using a chain hoist fixed to a 4 by 4 wooden beam laid across the opening in a floor above. Two 2 in. by 10 in. wood planks were laid across the 8 ft wide span. The workers walked out on these planks to secure the hoisted duct. Upon completion, the hoist was removed from the 8 ft by 16 ft roof opening where it was last fixed. Employee #1 was killed when he lost his balance and fell approximately 100 ft to the basement. No safety belts or safety lines were in use or made available. The floor openings beside the duct had not been covered on any of the floors below, except for the two 2 in. by 10 in. planks; these only covered 20 in. of the 4 to 6 ft wide gap between the duct and the side of the floor opening.