Abstract: At approximately 1:45 p.m. on May 30, 2006, Employee #1, a service technician for approximately fifteen years with Air-Tro Heating and Air Conditioning, Inc., located in Monrovia, CA, was working alone, repairing an HVAC unit located on the roof of an offsite building located in Pico Rivera, CA. The HVAC unit was located approximately 4 feet away from a skylight. Employee #1 used a metal extension ladder to access the roof of the 18-foot-tall building (measured from ground to top of parapet, actual height of roof is 15 feet). There was a pipeline running in between the skylight and HVAC unit. Employee #1 conducted diagnostic work on the HVAC unit. He then replaced a circuit board on the unit. Employee #1 fell through the skylight to the warehouse ground. The distance he fell was approximately 15 feet. He sustained a serious head injury. Employee #1 was transported by emergency medical services to Los Angeles County USC Medical Center in Boyle Heights, CA, where he was treated for a subdural hemorrhage, multi-system blunt trauma, and 1350 comatose rating. He was kept in the hospital for treatment for more than twenty-four hours. The exact cause of his fall is not known, since he has amnesia. The skylight did not have any markings on it. The skylight was not guarded. The skylight did not have a screen. Guardrails were not used. Personal fall protection was not used.