Table 1.

One example of extracting a chain of unsafe behaviors in a fall accident.

Accident Type	Fall
Occurrence Process	Two workers installed air-conditioning condensing pipes on the exterior wall of a building. The bracket of their hanging basket was fixed on the roof of the twenty-first floor, and the wire rope of the hanging basket on the west side was fixed on the bracket. However, the wire rope on the east side was fixed on the vertical structure of the glass curtain wall instead of on the bracket. Neither of the workers wore safety belts during the operation. When they installed the air-conditioning condensing pipe on the eighth floor, the wire rope on the east side was loose causing the east side of the basket to be imbalanced. The two workers fell 30 m to the ground.
Accident Causes	1. The workers fixed the wire rope on the east side to the vertical structure of the glass curtain wall instead of the bracket. 2. The workers engaged in high-altitude operations without a permit. 3. The workers did not wear safety belts during the operation.
Time Sequence of Unsafe Behaviors	Install or dismantle machines and equipment against procedures→engage in specialized operation without a permit→does not use all personal protective equipment (PPE)
Chain	B18→B14→B12