Employees were loading a flatbed trailer with deck slab forms using a 15-ton crane. After the last form was loaded onto the flatbed, two employees climbed on top of the form to unhook the rigging between the form and spreader bar. The spreader bar was hoisted up and the crane began to move toward the east end of the building. The crane boom struck the employee, who was knocked to the ground (about 13 feet below) and suffered a head injury. The employee was hospitalized.