Fatality of employee when he became detached from the lifting hook. A derrickman, who happened to be working the floor, put on a full body harness with an integrated bosun¿s chair and ascended to assist in retrieving the fallen pipe. He was being raised into the derrick via an air hoist. The derrickman was attached directly to the air hoist line via a Gunnebo OBK 13-8 hook . When the employee was raised to a height of 4 to 10 feet below the monkey board he began swinging to manoeuvre around the monkey board. During the swinging, he became detached from the hook and fell approximately 80 feet to the rig floor sustaining fatal injuries.