Abstract: On March 29, 2014, Employee #1, a heating, ventilation, and air conditioning (HVAC) mechanic employed by Control Air Conditioning Service Corporation, was working on a service call for an existing HVAC system at a commercial building. The system needing repair was located on the building's roof, and in order to access it, Employee #1 had to climb a 16-rung fixed metal ladder. As he climbed up the ladder, his hand slipped and he lost his balance. Employee #1 fell approximately 10 feet to a concrete surface below. Emergency services were called, and Employee #1 was transported to the hospital, where he was admitted and treated for multiple fractures including a fractured back. He remained hospitalized for three days. This event was reported by the employer to Cal/OSHA on March 10, 2014. During the subsequent investigation, it was determined that the employer was a contractor specializing in the service and repair of heating, air conditioning, and ventilation (HVAC) systems for commercial buildings.