Root cause analysis techniques

In addition to incident reporting systems, root cause analysis techniques can be used to evaluate the causes of serious incidents where resources are usually available for in-depth investigations. A practical example of root cause investigation methods is provided in Chapter 7. 

This is a simplified root cause analysis technique. The five W s are who, what, where, when, and why, and the two H s are how and how many. If these seven questions are answered, the problem will be specifically defined, with suggestions as to what the root cause might be. 

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. 

Many organisations already use root cause analysis techniques that allow the identification of critical factors in the occurrence of incidents. For each critical factor, related behaviours can be isolated. A number of these factors can be related closely to human error, violation or safety culture. Formal approaches are required to perform in-depth analysis of such factors and determine the root of human factors problems and how they could be dealt with. 

One of the simplest root cause analysis techniques is to determine the causes of accidents/ind-dents at different levels. During any hazard analysis we are always trying to determine the root cause of any accident or incident. Experts who study acddents often do a breakdown or analysis of the causes. They analyze them at three different levels ... 

However, in the case of a root cause analysis system, a much more comprehensive evaluation of the structure of the accident is required. This is necessary to unravel the often complex chain of events and contributing causes that led to the accident occurring. A number of techniques are available to describe complex accidents. Some of these, such as STEP (Sequential Timed Event Plotting) involve the use of charting methods to track the ways in which process and human events combine to give rise to accidents. CCPS (1992d) describes many of these techniques. A case study involving a hydrocarbon leak is used to illustrate the STEP technique in Chapter 7 of this book. The STEP method and related techniques will be described in Section 6.8.3. 

In the following sections, a number of methodologies for accident analysis will be presented. These focus primarily on the sequence and structure of an accident and the external causal factors involved. These methods provide valuable information for the interpretation process and the development of remedial measures. Because most of these techniques include a procedure for delineating the structure of an incident, and are therefore likely to be time consuming, they will usually be applied in the root cause analysis of incidents with severe consequences. 

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. 

To gather information about the factors which contributed to the above incident, interviews were held with the workers and their management. Relevant documentation such as standard operating procedures and documentation relating to the incident was also collected. A task analysis (see Case Study 3) of the job of the top floor person was carried out in order to examine the operations involved and the factors which could affect job performance. Two techniques were used for the analysis of this incident, namely variation tree analysis and root cause analysis. 

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. 

Checklist analysis tools can be a user-friendly means to assist investigation teams as they conduct root cause analysis.h) Each causal factor is reviewed against the checklist to determine why that factor existed at the time of the incident. The Systematic Cause Analysis Technique (SCAT)(9> is an example of a proprietary checklist tool. 

If the answer is YES, that is, the incident would have heen prevented or mitigated, and it is a negative event or undesirable condition, then the fact is a causal factor. Generally, process safety incidents involve multiple causal factors. This technique is equivalent to step 15 in Figure 9-7. Once identihed, the causal factors become the candidates to undergo root cause analysis. 

The use of checklists to supplement another root cause analysis method can be a very powerful technique, for example, human factors checklist(s) may be used in conjunction with logic trees. The checklist may be used as a guide during development of a logic tree, or as a check after the tree has been developed. The checklist essentially acts as a memory jogger to direct the investigation team. This is especially helpful if the team lacks previous experience in the subject matter. 

A technique for casual decomposition of complex problems and invention situations into effects and causing conflicts (contradictions). Helps to map and visualize all system conflicts as well as reveal hidden conflicts. Root cause analysis to identify root problems in inventive situations... 

By contrast, the lagging and leading indicator approaches can only identify underperforming management elements through the use of root cause analysis. As discussed in the previous chapter, such analyses are inherently subjective—different people and different techniques will come up with different answers as to why an event occurred. 

Physical contradictions as well as technical contradictions are usually crystallized during the problem analysis. Sometimes technical contradictions can be obtained by analysis techniques such as in the Root Cause Analysis framework or Goldratt s Theory of Constraints (Wilson et al. 1993). 

I often inform the person about the technique before I press them a bit to get to the root cause. Five is not a magic number the number of times you ask the question is situational. It is very effective at framing the conversation and engaging all involved In root cause analysis. Therefore, it is a very useful technique when conducting incident or accident investigations. Chapter 7 will be devoted to that important aspect of world-class safety. 

Root cause analysis is a most important technique that can be used in determining the direct cause and contributing factors for the mishap. Succinctly, the technique asks successive questions of why did this event happen until no further response is available and the root cause should be identified. 

Anderson, Bjorn and Fagerhaug Tom, Root Cause Analysis Simplified Tools and Techniques, 2nd ed., ASQ Quality Press, Milwaukee, WI, 2006. 

Techniques used in systems safety frequently have specific goals and areas that they can address. For example, some techniques are used to analyze the hardware and equipment aspects of the system while other techniques are used to assess the human aspect. From a safety metrics standpoint, systems safety techniques can be used to identify areas for improvement in the organization. While there are hundreds of system safety techniques available, some of the more commonly used are Fault Tree Analysis (FTA), Procedure Analysis, Failure Modes and Effects Analysis, and Root Cause Analysis. 

For a safety program to be effective, the safety climate needs to be supportive of the program. The safety climate includes management, workers, the physical equipment in the workplace, and the interfaces between the people and the environment. Perception surveys can be used to assess the status of the safety climate in the workplace. Key areas that perception surveys can assess include management support for safety and employees attitudes and beliefs about safety. Environmental conditions and interfaces between equipment and workers can be assessed using various system safety techniques. Examples of system safety techniques include root cause analysis and failure modes and effects analysis. 

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