Root cause of an accident

Accidents in industry occur for many reasons. A few of which can be attributed to mechanical failure, operational error (human error), and process upset, and design error. In order to understand tlie root cause of an accident, system safety appraaches have been put to use. 

The basic Domino Model is inadequate for complex systems and other models were developed (see Safeware [115], chapter 10), but the assumption that there is a single or root cause of an accident unfortunately persists as does the idea of dominos (or layers of Swiss cheese) and chains of failures, each directly causing or leading to the next one in the chain. It also lives on in the emphasis on human error in identifying accident causes. 

This case study provides insight into how organizational changes may not always be identified as one of the root causes of an accident until these issues are explored within the context of whether there were management systems in place to identify organizational changes that could impact process safety. 

While asking five whys wiU usually lead to a root cause, it is okay to ask six or seven whys if needed. When using this technique, remember that the focus is on identifying a broken or absent process, not a human or equipment failure. In the example above, an investigator could jump to the conclusion that not maintaining the vehicle to the recommended service schedule is operator negligence however, the operator may not have the training or parts to maintain the vehicle. In this case, a sixth why may be necessary in order to get to the true root cause of an accident. 

Remember, your goal should be to identify the failures at a deep level in order to prevent, not only a recurrence of the accident, but all of the potential accidents stemming from the same root cause. For more information about determining the root cause of an accident, refer to Step 8. 

To an outside observer, it appears as if neither the official spokesperson nor the manager considered the community s reaction as important. Furthermore, by disciplining the workers involved in the accident, there appears to be an attitude of blaming the operator rather than looking for root causes of the accident. In fact, it is likely that these managers did indeed care very much about safety, but this is not the perception that was created with these actions. 

Root cause The one cause that leads all of the others when conducting an investigation of an outcome. In accident or safety incident investigations, the pursuit of effective corrective actions is dependent on defining the root cause of the accident or incident. 

Traditionally the only reasons for accident investigations were to appropriate blame and find a guilty party. This will never solve the problem or determine the root causes of downgrading events, and will not fix the real cause of the problem. This is termed prescription without diagnosis. Finding one cause of an accident is totally insufficient, as there are always a number of reasons for an action or incident. 

The root causes of most accidents are found during an analysis of the management system factors (Fig. 18-19). This major branch of the chart addresses the why issues. Specific factors and branches to be analyzed include... 

Recommended preventive actions should make it very difficult, if not impossible, for the incident to recur. The investigative report should list all the ways to foolproof the condition or activity. Considerations of cost or engineering should not enter in at this stage. The primary purpose of incident investigations is to prevent future occurrences. Beyond this immediate purpose, the information obtained through the investigation should be used to update and revise the inventory of hazards, and/or the program for hazard prevention and control. For example, the Job Safety Analysis should be revised and employees retrained to the extent that it fully refiects the recommendations made by an incident report. Implications from the root causes of the accident need to be analyzed for their impact on all other operations and procedures [6]. 

When determining the causes of an accident, don t jump to conclusions. Don t be predictive. Rather, deduct the facts by a systematic identification of immediate causes from which the root causes can be derived. 

Serve as an independent body to determine the root causes of the accident... 

Root cause analysis is used when there are multiple problems with a number of causes of an accident. A root cause analysis is a sequence of events that shows, step by step, the events that took place in order for the accident to occur. Root cause analysis puts all the necessary and sufficient events and causal factors for an accident in a logical, chronological sequence. It analyzes the accident and evaluates evidence during an investigation. It is also used to help prevent similar accidents in the future and to validate the accuracy of preaccidental system analysis. It is used to help identify an accident s causal factors, which, once identified, can be fixed to eliminate future accidents of the same or of similar nature. 

In the injury/illness tree (Figure 1) EHS pros spend the majority of their time burrowed down to find and prevent the root cause(s) of an event, i.e. accident. Pros generally have little involvement in the upward effects, i.e. branches that follow an event. Whether the root cause of the accident is an unsafe condition or unsafe act, prevention requires motivation by both management and employees to prevent a similar reoccurrence. 

Root causes are the most basic cause of an accident/incident, i.e. a lack of adequate management control resulting in deviations and contributing factors. Stop rules have to be applied in the investigation into the accident sequence in order to avoid the garden-of-Eden problem where we look for accident causes far away from the accident site in time and space (Rasmussen, 1993). 

The MORT system uses the term root cause in the sense of the most basic cause of an accident or incident (Cornelison, 1989). It can be traced back to a lack of adequate management control that results in substandard practices and conditions and subsequently in an accident. 

Root cause of accidents Most basic cause of an accident/incident, i.e. a lack of adequate management control resulting in deviations and contributing factors. 

When technical defects and employee error contribute to an accident, they are often linked to underlying safety system conditions that have created a hazardous situation and unsafe behaviors fhat are manifesfed in fhe surface causes of accidenfs. These underlying conditions are typically the root cause of fhe accident. The "accident weed" shown in Figure 3-4 is often used to illustrate the relationship between surface and roof causes, and common examples of each are shown. 

April and November 1997 two of the incidents occurred after installation of catalytic oxidizers in ETO exhaust ventilation systems. As a result of an accident one employee was killed, 59 others were treated at a hospital, and 3 were hospitalized. Approximately 2,500 people were evacuated from a 1-mile radius around the Accra Pac plant. Investigators Conclusion The investigators found the following root causes of the accident ... 

The National Safety Council has embarked on a program to eliminate, as far as possible, the word accident from their vocabulary. Their annual publication Accident Facts, will now be titled. Injury Facts. If management places a focus on the root causes of an injury in the workplace, the word accident should not be used. This way of thinking may take years to modify, but the effort may well be beneficial to all of industry—both management and labor. 

By examining the various types of evidence collected during the investigation process and combining this information with the notes, photographs, and sketches, this should help you to determine a root cause of the accident. And, if you need clarification on any of this information, consulting with the witnesses and victims of the accident may be an additional option. 

When looking for root causes to an accident, it will be helpful for you to determine why an employee acted the way he/she did prior to the accident. Or, you might want to look at the specific conditions of the task just prior to the accident. 

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