Static versus Dynamic Views of Systems

Major accidents occur from the chance simultaneous occurrence of 

Woods has stressed the importance of adaptation in accidents. He describes organizational and human failures as breakdowns in adaptations directed at coping with complexity, and accidents as involving a drift toward failure as planned defenses erode in the face of production pressures and change [214], 

Humans and organizations can adapt and still maintain safety as long as they stay within the area bounded by safety constraints. But in the search for optimal operations, humans and organizations will close in on and explore the boundaries of established practice. Such exploration implies the risk of occasionally crossing the limits of safe practice unless the constraints on safe behavior are enforced. 

To handle system adaptation over time, our causal models and safety techniques must consider the processes involved in accidents and not simply events and conditions Processes control a sequence of events and describe system and human behavior as it changes and adapts over time rather than considering individual events and human actions. To talk about the cause or causes of an accident makes no sense in this systems or process view of accidents. As Rasmussen argues, deterministic causal models are inadequate to explain the organizational and social 

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