An employee was loading a skid holding 947 pounds of sheet metal onto a 40-foot flatbed trailer using a sheet lifter attached to an overhead crane. Standing on the platform of a loading ladder at the middle of the trailer, the employee began to operate the overhead crane. The sheet lifter hit the edge of the loading ladder and tipped it over. The employee fell with the ladder, holding onto it, and struck the back of his head on the ground. He suffered a concussion and was hospitalized.