Applying the New Model

To summarize, STAMP focuses particular attention on the role of constraints in safety management. Accidents are seen as resulting from inadequate control or enforcement of constraints on safety-related behavior at each level of the system development and system operations control structures. Accidents can be understood in terms of why the controls that were in place did not prevent or detect maladaptive changes. 

Accident causal analysis based on STAMP starts with identifying the safety constraints that were violated and then determines why the controls designed to enforce the safety constraints were inadequate or, if they were potentially adequate, why the system was unable to exert appropriate control over their enforcement. 

In this conception of safety, there is no root cause. Instead, the accident cause consists of an inadequate safety control structure that under some circumstances leads to the violation of a behavioral safety constraint. Preventing future accidents requires reengineering or designing the safety control structure to be more effective. 

Because the safety control structure and the behavior of the individuals in it, like any physical or social system, changes over time, accidents must be viewed as dynamic processes. Looking only at the time of the proximal loss events distorts and omits from view the most important aspects of the larger accident process that are needed to prevent reoccurrences of losses from the same causes in the future. Without that view, we see and fix only the symptoms, that is, the results of the flawed processes and inadequate safety control structure without getting to the sources of those symptoms. 

To understand the dynamic aspects of accidents, the process leading to the loss can be viewed as an adaptive feedback function where the safety control system performance degrades over time as the system attempts to meet a complex set of goals and values. Adaptation is critical in understanding accidents, and the adaptive feedback mechanism inherent in the model allows a STAMP analysis to incorporate adaptation as a fundamental system property. 

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