Abstract: Employees #1 and a coworker were assigned to unload a Clark C-500-YS80 rubber-tired forklift from a flatbed trailer. A JLG 14000 boom truck was set up beside the trailer to pick up the forklift and set it on the ground. The boom truck, with outriggers down, was set at a 21 foot boom radius with 40 feet 5 1/2 inches of boom extended. Employee #1, the truck operator, estimated but did not confirm that the forklift's weight was 6,000 pounds. Its actual weight was not determined. The manufacturer's load chart for this set-up indicates a total 'below-the-boom capacity' rating of 6,000 pounds. The actual 'below boom load weight' was calculated as 13,680 pounds, an overload of 128 percent. The boom mount bolts failed and the boom fell toward the rear of the truck, pinning Employee #1 between the rigging box and the operator's stand. He sustained a bloody nose. Employee #1, who was wearing a hard hat, had 18 years experience with boom trucks and had previously completed a similar lift. The boom truck was equipped with a boom overload system, which the employees relied on to help prevent an overload. Employee #1 said that this system, which has a history of malfunction and repair, did not function. The employees had received crane training. The accident can be attributed to crane overload and failure of the backup overload system.