Abstract: Employee #1, who worked for a window installation contractor, was on the second floor of the San Pedro Post Office, approximately 18 to 20 ft above floor level. He was using a rubber hammer to pound on a window to loosen it from its frame. After the window was loosened, a hydraulic boom with a basket was used to pull it from the frame. Employee #1 was pounding on the window when the boom operator pulled it with the boom. The window popped out just as Employee #1 was swinging his hammer. Employee #1 fell through the window opening, fracturing three ribs. Causal factors to this accident included Employee #1 working without a lanyard and harness, and the boom operator working the boom without clear instructions.