Abstract: On September 29, 1990, Employee #1 and a coworker, both AT&T systems installer technicians (electricians), were installing wire and speakers along inside walls 20 to 25 feet high for in-plant communications. To reach the elevated work areas, the technicians had a stepladder, an extension ladder, and an Up-Right air lift scaffold, furnished by the company. The technicians decided to use the air lift scaffold unit. They extended the scaffold to a height of 18 feet 3 inches and did not secure it with outriggers because the wall configuration and the presence of a traffic guard post near the wall prevented them from doing so. The employees also did not use guy wires, tie-offs, or bracing. The base of the unit was 29 3/4 inches by 32 inches. At approximately 11:35 a.m., Employee #1 was in the lift's platform enclosure when he and the other technician decided to move the unit a few inches to gain a better position. As they did, the unit tipped away from the wall, first hitting the hood of an AT&T van parked close by, then the concrete floor. Employee #1 died in the hospital in the early afternoon the same day.