Root causes analysis process is a four-step process involving :
1. Data collection and preservation
2. Investigation and Analysis
3. Root cause identification
4. Recommendation generation and implementation.
Step 1: Data Collection and Preservation
The first step in the analysis is to gather data covering men / machine / materials / methods or others as applicable. Without complete information and an understanding of the incident, the causal factors and root causes associated with the incident, cannot be identified.
- People involved should be interviewed.
- Record should be reviewed.
- SOP adequacy to be checked.
- Previous history to be referred and data collected.
Step 2: Investigation and analysis (by using FTA method)
FTA provides a way for investigators to organize and analyze in chronological way the information gathered during the investigation and to identify gaps and deficiencies in knowledge as the investigation progresses. The FTA is simply a sequence diagram that describes the events leading up to and following an incident, as well as the conditions surrounding these events. The final step in FTA involves identifying the major contributes to the incidents (i.e. causal factors).
Procedure for Root Cause Analysis
- Preparation of the FTA shall begin as soon as investigators start to collect information about the incident. They shall begin with a “skeleton” chart that is modified, as more relevant facts are uncovered.
- Data collection shall continue until the investigators are satisfied with the thoroughness of the chart and hence are satisfied with the thoroughness of the investigation.
- When the entire incident has been charted out, the investigators are in a good position to identify the major contributors to the incident. These are labeled as causal factors
After identification of all the causal factors, the investigators shall begin root cause
- identification. Each causal factor shall be analysed, one at a time, using the questioning techniques, i.e. how, why, what, when, who & where.
Procedure for FTA
The procedure for performing a fault tree analysis consists of the following steps after defining the TOP event for analysis and data collection :
1. Define the treetop structure. Determine the primary difficult sources (major factors like events / resource / conditions) that most directly lead to the TOP event. (LEVEL-1)
2. Explore each branch of primary difficulty source in successive levels of detail. Analyse the major factor in details to get possible type of difficulties under individual major factor. (LEVEL-2)
3. Explore each branch of individual type of difficulty to find major root cause category. Analyse each individual type of difficulty by using tools like ‘WHY WHY ANALYSIS’ to get possible major root causes category. (LEVEL-3)
4. Explore each branch of individual “major root cause” category to find possible “near root cause”. Further, analyse each individual” major root cause” by using tools like “WHY WHY ANALYSIS” to get possible near root causes. (LEVEL-4)
5. Solve the fault tree for the combinations of events, resource and conditions contributing to the TOP event to pinpoint the actual / near by root cause. Examine the fault tree model to identify all the possible combinations of events, resource and conditions that can cause the TOP event of interest. A combination of events, resources and conditions sufficient and necessary to cause the TOP event is called a minimal cut set.
6. Identify important dependent failure potentials and adjust the model appropriately. Study the fault tree model and the list of minimal cut sets to identify potentially important dependencies among events, resource and conditions. This will help to pint point the actual root cause or close to it. (LEVEL-5)
7. Use of results in decision making. Use results of the analysis to identify the most significant vulnerabilities in the system and to make effective recommendations for reducing the risks associated with those vulnerabilities.
Step 3: Root Cause Identification
Root cause identification, involves the use of a decision tree to identify the underlying reasons for each causal factor identified during FTA. The identification of root causes, helps the investigator of a specific incident determine the reasons why the incident occurred so that the reasons how the incident can be fixed.
Step 4: Recommendation Generation and implementation
The next step is the generation of recommendations. Following identification of the root cause(s) for a particular causal factor, achievable recommendations for preventing its recurrence must be generated.
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