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Here’s the press report about an incident at a west coast refinery …

They think that someone working in the area accidentally hit a button that shut down fuel to a boiler. That caused a major portion of the refinery to shut down.

 At least one Causal Factor for this incident would be “Worker accidentally hits button with elbow.”

If you were analyzing this Causal Factor using the Root Cause Tree®, where would you go?

Of course, it would be a Human Performance Difficulty.

When you reviewed The Human Performance Troubleshooting Guide, you would answer “Yes” to question 5:

“Were displays, alarms, controls, tools, or equipment identified or operated improperly?”

 That would lead you do evaluating the equipment’s Human Engineering.

Under the Human-Nachine Interface Basic Cause Category, you would identify the “controls need improvement” root cause because you would answer “Yes” to the Root Cause Tree® Dictionary question:

“Did controls need mistake-proofing to prevent unintentional or incorrect actuation?”

That’s just one root cause for one Causal Factor. How many other Causal Factors were there? It’s hard to tell with the level of detail provided by the article. I would guess there was at least one more, and maybe several (there usually should be for an incident of this magnitude). 

At least one of the corrective actions by the refinery management was to initially put a guard on the button. Later, the button was removed to eliminate the chance for human error. 

Are there more human-machine interface problems at this refinery? Are they checking for them to look for Generic Causes? You can’t tell from the article.

Would you like to learn more about understanding human errors and advanced root cause analysis? Then you should attend the 5-Day TapRooT® Advanced Root Cause Analysis Team Leader Training. See public course dates at:

And click on the link for the continent where you would like to attend the training.