Abstract: At approximately 9:00 a.m. on November 17, 2014, an employee was operating an articulating aerial boom lift to reach exterior piping work at a height of 25 feet and greater up between two building structures. At one point the employee maneuvered and repositioned the aerial lift which caused the lower boom section to be located over top of a large steel bark hopper that was setting alongside the building. During the boom decent the boom became hung up on top of the hopper ledge which caused the aerial lift chassis rear tires to lift approximately 18 inches off the pavement. After the boom broke free from the structural bind, it caused the equipment chassis to set down back down on the ground rapidly. This caused the boom to have a snap whip action and catapulted the employee out of elevated platform. The aerial lift equipment did not turn over and the boom remained in the upright position. The platform came to rest at 19 feet above the pavement.