Abstract: At approximately 7:30 p.m. on November 23, 2005, Employee #1 was working for a company that manufactured a variety of concrete blocks for the construction industry. He was a regular employee of his employer. He was operating a Columbia Model Number UL26 block unloading unit with a chain conveyor. He was clearing a 26 inch wide by 18.5 inch long by 0.375 inch thick metal pallet carrying concrete blocks that had jammed at a point over the pallet sensor just as it entered a depalleter guide. Although Employee #1 thought he had turned off the power to both the chain conveyor and the unloader unit, the unloader was still energized and in automatic mode. As he squared the pallet so that it would move into the depalleter guide correctly, he exposed the pallet sensor. It directed the still-operational unloader to unload more pallets from the rack onto the chain conveyor. As the unloader moved forward, Employee #1 was trapped between it and the vertical frame of the chain conveyor. He sustained multiple fractures of his right ankle. He was taken to Desert Hospital in Palm Springs, CA, for treatment. Surgery was performed, and he was hospitalized for three to four days.