The Accuracy of Root Cause Analysis

By Vince Abernathy

Root cause analysis is typically performed whenever there is an incident, however how accurate and relevant are the results? There is a fundamental belief that root cause analysis will identify the one element, which if removed or solved will stop any recurrence of the problem again. In theory that is fine, but in practice there are always simplifications and assumptions which deviate from the real world in the root cause model.

How many times do you encounter an investigation outcome along the lines of, "Root cause determination is failure to follow standard procedure"?

This is a very common result of many investigations, however it stems from a highly misplaced understanding in what root cause analysis is actually telling us.

Let's look at a commonly used, working definition of root cause analysis:

"Root cause analysis is that analysis used to identify and define the fundamental event which results in the occurrence of the problem."

That works fairly well for our general purposes, however it ignores the fact that problems are not the product of one root cause in practice, but instead are the product of the operation of the processes or systems which are in operation.

This is moving us towards a systems approach to problem solving.

Consider a systems approach to be a way of looking at the various components of a process which are working together to perform a function. Within each system, there will be sub-systems which can be considered in isolation as long as there impact is viewed within the totality of the overall system. This is a holistic approach to problem identification and problem solving.

Take an aircraft as an example. The aircraft can be viewed as one system, however we can break the numerous parts of the plane down into sub-systems: engines, avionics and flight control, structural components such as wings and so on. Each sub-system can be viewed in isolation, however they must also be looked at in the context of the entire system too -how would an aircraft function without wings for instance.

The underlying point is that no system functions in isolation - even when we consider the entire aircraft. How can an aircraft operate without a runway to land and take-off from, or without a supply system to provide aviation fuel or with air traffic control and navigation beacons?

If the system itself is not operating in isolation, then how are we able to view a single cause as being responsible for a problem? The reality is we cannot, and therein lies the fundamental weakness of root cause analysis - it determines what the isolated event is that creates a problem, however problems do not result in an isolated environment.

Returning to our original investigation result of "Failure to follow procedures", how reliable is this as a final assessment in light of a systems approach? A holistic approach to root cause analysis would not have resulted in one instance of failure, it would have uncovered several failures: faulty equipment, supervisory and management failures or even a failure within the procedures themselves, all of which contributed to the failure in question.

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