An employee was operating an aircraft push tractor in reverse to go from one gate to the next. While passing a parked belt loader vehicle, the push tractor and the operator's upper body made contact with the conveyor boom of the parked belt loader vehicle. The employee sustained rib fractures, a non-displaced T5 fracture, a right pneumothorax, a periaortic hematoma, and a sternum fracture. The employee was hospitalized.