Incident causation theory

To be effective the investigation must apply an approach which is based on basic incident causation theories and use tested data analysis techniques. Investigating incidents to determine root causes and make recommendations can be as much an art as a science. Within the industry, best practices in incident investigation have evolved substantially in the last 20 years. This chapter provides a brief overview of some of the more relevant causation theories. 

Theoretical incident concepts and associated models have evolved from investigations into the how and why of case histories. Resulting insights have made it possible to better explain and understand incident causation. There are many other incident causation theories besides the ones presented in this chapter, such as the Process Theory. (See the additional references for this chapter.) Key theories on incident causation discussed in this overview are ... 

Another fallacy somewhat related to the fear of discipline is that getting rid of the incident-prone individuals will prevent future incidents. Studies have shown that fewer than 20% of the incidents involved a repeater.O) The incident proneness theory is generally discredited as a flawed incident causation theory, ft is probably more likely that repeaters are just less adept at hiding near misses and incidents or perhaps they are more proactive or open about fixing the problems when they are involved. 

Promoting exploration of incident causation theory, knowledge of which is both fundamental and vitally needed for the practice of safety. 

Several theories of incident causation exist and each has associated investigation techniques. Incident investigators use their judgment to make adaptations to selected techniques based on the size and complexity of the investigation effort. Judgment based on knowledge and experience is important in determining how and why an incident occurred. 

Analysis, that can assist with the identihcation of causal factors. The concepts of incident causation encompassed in these tools are fundamental to the majority of investigation methodologies. (See Chapter 3 for information about the Domino Theory, System Theory, and HBT Theory.) The simplest approach involves reviewing each unplanned, unintended, or adverse item (negative event or undesirable condition) on the timeline and asking, Would the incident have been prevented or mitigated if the item had not existed If the answer is yes, then the item is a causal factor. Generally, process safety incidents involve multiple causal factors. 

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.)... 

A theory of accident (incident) causation proposed in the early twentieth century, by various researchers, which has been discredited. Originally it used to attribute the cause of accidents to personality traits of individuals or groups of workers. In 1971,... 

A theory of incident causation developed circa 1957, which postulates that individuals who cannot achieve some form of adjustment with their work and work environment will tend to have more incidents than others. The failure to adjust is caused by a range of physical and psychological stressors. 

A classic incident theory is H.W. Heinrich s domino theory of causation, which has had a significant influence on practical incident investigation. (2) Many adaptations of Heinrich s original proposal have been developed by later researchers. Heinrich labeled his five dominoes as follows ... 

Heinrich s approach is to identify, evaluate, and work on the middle dominoes, not just the last one or two dominoes in the line. The domino theory has significant limitations. The basic assumption is that there is a linear relationship between causation and progression. In other words, one occurrence follows another and ends in an incident. In the context of process-related incidents, this assumption is not always valid. Often parallel occurrences coincide to result in an incident rather than occurring as purely sequential occurrences. Nevertheless, the domino theory can provide a useful conceptual framework for simple incidents. 

Both the integrative model by Smillie Ayoub (1975) and the deviation concept by Kjellen (1984a) connect the general systems theory to the sequencing and energy models of accident causation. They encompass technical, organizational and human components of the system. Various methods of system safety analysis (e.g. fault tree analysis, incidental factor analysis) support the identification of technical and human deviations as well as the analysis of the conditions and consequences of these deviations. From the discussion of near misses and conflicts it became clear that frameworks of accident causation should cover all kinds of incidents, thus becoming frameworks of incidents. 

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