Causal factor identification process

The process of evidence gathering, timeline development, scenario determination, and causal factor identification is somewhat iterative, and therefore some of the tools and quality tests previously described may assist in causal factor identification. More specifically, barrier analysis and change analysis, together with a completeness test, can ensure that all valid causal factors are identified. 

The design of most process plants relies on redundant safety features or layers of protection, such that multiple layers must fail before a serious incident occurs. Barrier analysis ) (also called Hazard-Barrier-Target Analysis, HBTA) can assist the identification of causal factors by identifying which safety feature(s) failed to function as desired and allowed the sequence of events to occur. These safety features or barriers are anything that is used to protect a system or person from a hazard including both physical and administrative layers of protection. The concepts of the hazard-barrier-target theory of incident causation are encompassed in this tool. (See Chapter 3.)... 

Using the augmented control structure, the remaining activities in STPA are to identify potentially hazardous control actions by each of the system components that could violate the safety constraints, determine the causal factors that could lead to these hazardous control actions, and prevent or control them in the system design. The process thus involves a top-down identification of scenarios in which the safety... 

To answer that question for myself, I thought about the studies I made of over 1200 incident investigation reports completed by supervisors or investigation teams. I have not had an experience with an organization in which avoiding the reality of root causal factors was an active process. By that I mean—I have not encountered a situation in which instructions were given to avoid the identification of systems causal factors. 

Although the input, decision, output classification is a very simplistic representation of human information processing, it can be a key tool for identifying fhe causal factors and the best area of focus for remedial action. In addition it provides a systematic, straightforward tool for high-level initial identification of human error potential. 

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