Incident causation

FIGURE 1.3 The Dynamics of Incident Causation (adapted from Reason, 1990). 

This section discusses the basics of determining incident causation and describes the general categories of incidents—from near miss to major catastrophe. It examines the anatomy of process incidents as related to theoretical models of incident causation. 

This chapter describes human factor considerations in incident causation. It provides insight and tools to identify and address applicable human factors issues during an investigation. 

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. 

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. 

Investigators can systematically analyze data from past incidents to identify lessons learned and develop incident stereotypes. This makes it possible to develop a model displaying the anatomy of a process-related incident using a conceptual framework. Figure 3-1 provides a tool to help us understand incident causation. 

Historic incident data show that latent failures, also called latent conditions, have played an important role in incident causation. The term latent failure implies the condition is dormant or hidden. Normally the latent failure can be revealed before an incident through testing or auditing during typical operations within the process as shown in Figure 3-2. 

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 ... 

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. 

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. 

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.)... 

Incident Stereotype— A fixed or general pattern of incident causation. From a review of historical incident data it can be possible to identify classes of incidents, each with certain features (or typical, repeated patterns) in common that is, incident stereotypes are defined. 

In this chapter a simple model of incident causation is presented and the relative importance of three groups of factors contributing to industrial safety will be discussed Technical, Organisational and Behavioural Factors. Historic trends or fashions focussing on one of these thpee factors will be described, followed by recent results of the situation in the chemical process industry in the Netherlands. 

Figure 2.1 shows a simple model of the main components involved in incident causation, and also defines three basic terms used throughout this... 

Incident causation is assumed to progress from the bottom to the top, which means that chances for early prevention of accidents decrease as you get closer to the top. The order of incident analysis is assumed to be top-down, but with different starting points in the iceberg depending On the type (or level) of data that trigger the detection in the first place. It is also assumed that modem investigation techniques will always try to get as far to the bottom of... 

Ballantyne, B., Medical management of the traumatic consequences of civil unrest incidents. Causation, clinical approaches, needs, and advanced planning criteria, Toxicol. Rev., 25, 155-197, 2006c. 

In MORT Safety Assurance Systems, Johnson wrote succinctly about the multifactorial aspect of incident causation, as in the following ... 

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

This chapter addresses the need for safety professionals to adopt an incident causation model, a thought process based on a sound understanding of the hazards-related incident phenomenon and which, when applied, identifies the reality of the causal factors in the incident process. 

Safety professionals apply differing and contradictory incident causation models, and the work of some of them is misdirected and ineffective. Professional safety practice requires that the advice given to avoid, eliminate, or control hazards be based on a sound incident causation model, a thought process, so that, through the application of that model, the desired risk reduction is attained. That will not occur if the causation model used does not require identifying the actual causal factors. 

At the Safety Technology 2000 symposium held by the American Society of Safety Engineers in June of 1995, many of the papers presented made specific reference to or alluded to an accident causation concept. From a review of those papers, it was obvious that the beliefs of safety professionals about concepts of hazards-related incident causation are far from consensus. These are the extremes in the variations expressed on incident causation in those papers ... 

If we who call ourselves safety professionals are to be tmly perceived as professionals, we must resolve this matter of a generally accepted hazards-related incident causation model. A major study on this subject would be to our advantage. 

Safety professionals investigating a given hazards-related incident should identify the same causal factors, allowing for an occasional exception. That is unlikely if their understandings of incident causation, and the thought processes they apply, have different and sometimes contradictory foundations. 

INCIDENT CAUSATION MODELS REPRESENT GREAT DIVERSITY OF THINKING... 

Several authors have recognized, with some fmstration, the absence of and a serious need for a generally accepted accident causation model. Robert E. McClay addressed the subject in his paper titled Toward a More Universal Model of Loss Incident Causation ... 

It is not good science to use terms that cannot be defined. Definitions of the terms unsafe conditions and unsafe acts that can withstand thorough inquiry are scarce. I believe that the terms unsafe act and unsafe condition should be eliminated from the vocabulary of safety professionals, to be replaced by terms such as causal factors or risk factors—which can be defined. Safety professionals should also cease using their dominoes or the falling domino idea They are overly simpMstic representations of incident causation. 

Toward a More Universal Model of Loss Incident Causation by Robert E. McClay... 

Professional safety practice requires that the advice given be based on a sound hazards-related incident causation model so that, through the application of that advice, hazards are effectively avoided, eliminated, or controlled and risks are reduced. 

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