Root Cause Analysis

Root cause analysis (RCA) is a method of problem solving that tries to identify the root causes of faults or problems that cause operating events.

RCA practice tries to solve problems by attempting to identify and correct the root causes of events, as opposed to simply addressing their symptoms. By focusing correction on root causes, problem recurrence can be prevented. RCFA (Root Cause Failure Analysis) recognizes that complete prevention of recurrence by one corrective action is not always possible.

Nevertheless, in the U.S. nuclear power industry the NRC requires that "In the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to prevent repetition." In practice more than one "cause" is allowed and more than one corrective action is not forbidden.

Conversely, there may be several effective measures (methods) that address the root causes of a problem. Thus, RCA is often considered to be an iterative process, and is frequently viewed as a tool of continuous improvement.

RCA is typically used as a reactive method of identifying event(s) causes, revealing problems and solving them. Analysis is done after an event has occurred. Insights in RCA may make it useful as a pro-active method. In that event, RCA can be used to forecast or predict probable events even before they occur. While one follows the other, RCA is a completely separate process to Incident Management.

Root cause analysis is not a single, sharply defined methodology; there are many different tools, processes, and philosophies for performing RCA. However, several very-broadly defined approaches or "schools" can be identified by their basic approach or field of origin: safety-based, production-based, process-based, failure-based, and systems-based.

• Safety-based RCA descends from the fields of accident analysis and occupational safety and health.
• Production-based RCA has its origins in the field of quality control for industrial manufacturing.
• Process-based RCA is basically a follow-on to production-based RCA, but with a scope that has been expanded to include business processes.
• Failure-based RCA is rooted in the practice of failure analysis as employed in engineering and maintenance.
• Systems-based RCA has emerged as an amalgamation of the preceding schools, along with ideas taken from fields such as change management, risk management, and systems analysis.

Despite the different approaches among the various schools of root cause analysis, there are some common principles. It is also possible to define several general processes for performing RCA.