Abstract: At approximately 9:00 a.m. on November 23, 1992, Employee #1 was preparing to reinstall a white telephone wire on the wall next to a glass window using a 4 ft aluminum ladder. His left hand was carrying his tools and he was stepping up on the second rung when he lost his balance and fell sideways on his right arm as he turned to stop his fall. Employee #1's right arm went through the glass window. He suffered a lacerated arm and was taken to the hospital for emergency treatment. Employee #1 has about 15 years experience and was trained as an electrical contractor; he was presently a comanager of the facility. No equipment defect nor any malfunction of Employee #1's perception system with respect to this task were found.