Abstract: At approximately 5:00 p.m. on September 2, 1999, Employee #1 seriously injured his back while stepping off a hydraulic platform used to paint large aircraft. This apparatus is known as a Stacker. The worksite consisted of a large industrial building capable of fitting a 747 Boeing aircraft. Employee #1 did not report the accident to supervision until the next day. He was not transported to any medical facility after the accident. Then he went on disability and has not returned to work. On September 27, 2001, Employee #1 had surgery to remove a crushed disk from the lower lumbar and lumbar-sacral area and was hospitalized for four days. Additional information: Stackers are located on either side of the aircraft, both front and rear. The Stackers are capable of reaching all points of the aircraft and when lowered to ground level, rest approximately 15 in. from the floor. Employee #1 was not being supervised at the time of the accident. Employee #1 was very experienced in the operation of the Stacker and had been trained in its use. At the time of the accident Employee #1 stepped off the Stacker, in an apparently awkward motion and wrenched his back.