Root cause incident investigation process

Thorough and effective analyses of workplace incidents are critical components of a comprehensive safety management system. Yet, many incident analysis processes (i.e., accident investigations) fall short. They frequently fail to identify and resolve the real root causes of injuries, process incidents and near misses. Because the true root causes of incidents are within the system, the system must change to prevent the incident from happening again. 

The method is well-structured and provides clear, standardized procedures on how to conduct an investigation and represent the incident process. Also it is relatively easy to learn and does not require the analyst to have a detailed knowledge of the system under investigation. However, the method alone does not aid the analyst in identifying root causes of the incident, but rather emphasizes the identification of the propagation of event sequences. This is an important aspect of developing a preventive strategy. 

The case study has documented the investigation and root cause analysis process applied to the hydrocarbon explosion that initiated the Piper Alpha incident. The case study serves to illustrate the use of the STEP technique, which provides a clear graphical representation of the agents and events involved in the incident process. The case study also demonstrates the identification of the critical events in the sequence which significantly influenced the outcome of the incident. Finally the root causes of these critical events were determined. This allows the analyst to evaluate why they occurred and indicated areas to be addressed in developing effechve error reduchon strategies. 

This chapter provides an overview of a management system for investigating process safety incidents. It opens with a review of management responsibilities and presents the important features that a management system must address to be effective. It examines systematic approaches that help implement incident investigation teams, root cause determinations, recommendations, follow-up, and documentation. 

This chapter addresses methods and tools used successfully to identify multiple root causes. Process safety incidents are usually the result of more than one root cause. This chapter provides a structured approach for determining root causes. It details some powerful, widely used tools and techniques available to incident investigation teams including timelines, logic trees, predefined trees, checklists, and fact/hypothesis. Examples are included to demonstrate how they apply to the types of incidents readers are likely to encounter. 

One approach is to mesh all investigation and root cause analysis activities under one management system for investigation. Such a system must address all four business drivers (1) process and personnel safety, (2) environmental responsibility, (3) quality, and (4) profitability. This approach works well since techniques used for data collection, causal factor analysis, and root cause analysis can be the same regardless of the type of incident. Many companies realize that root causes of a quality or reliability incident may become the root cause of a safety or process safety incident in the future and vice versa. 

Disciplinary action may be appropriate if malicious or criminal intent is positively identified as a root cause. An example would be when an investigation reveals horseplay, practical jokes, fights, or even sabotage was among the root causes. These activities have no place in any workplace and are especially undesirable in the chemical processing industry. It is most likely that a company s employee handbook, human resources documents, or union contract addresses these situations and communicates the policy in advance of an incident. In short, the investi-... 

The investigation committee method is another unsuccessful approach. This unstructured approach is historically significant and was judged inadequate for investigating process safety incidents because it produced incomplete and inconsistent results. It often did not find the root cause level or all the root causes. 

The incident investigation team s complete report is attached in the Appendix D and details of the root causes are discussed. The root causes of the incident relate to several process safety management areas ... 

The following case study describes the investigation work process for a hypothetical occurrence using a logic tree based multiple root-cause systems approach. An example incident investigation report follows the work process description. The example is intended for instructive purposes only descriptions of process equipment and conditions are not intended to reflect actual operating conditions. 

Philley, Jack, Investigate Incidents with Multiple Root Cause, Hydrocarbon Processing, Sept. 1992, pp. 77-80. 

The terms root cause or multiple root causes appear several times without a clear definition. When Jack Philley teaches the Investigating Process Safety Incidents course for the AIChE, he offers several clear definitions. He describes a root cause as a prime reason, underlying cause, and most often associated with breakdowns or flaws in the management systems. Furthermore, Philley s class notes point out definitions from the Department of Energy Guidelines in his handout, which states ... 

The Causal Factors Chart is a formal, and systematic, incident investigation and root cause analysis technique. The technique depicts the events and conditions leading up to an incident. It combines critical thinking, logical analysis, and graphic representations to analyze and depict an incident event scenario. It helps strncture the analysis and data gathering processes to ensure necessary and snfficient information is collected. The CFC also has been applied to Root Cause Analysis. The CFC is sometimes referred to as the Events and Causal Factors (ECF) chart. The ECF chart depicts the necessary and sufficient events and causal factors associated with a specific incident scenario. 

So let s demonstrate how this might work, using an incident described earlier. Keep in mind that this is a simple exercise, and because you have not conducted a thorough investigation to collect all of the facts, it is possible your conclusions could be different from those shown in the example below. This is likely because each of us makes different assumptions that may or may not be correct. Remember that you can use this process to examine any incident that has involved you to learn more about the root causes and derive lessons that might prevent those from happening again. 

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