I've read many root cause analyses that ended with the same two words: human error.
The technician applied the wrong setting. The operator opened the wrong switch. The engineer missed a step. Corrective action: retraining. Case closed.
And a few months later, the same failure came back with a different name on the report.
What I've learned: human error is where a good analysis starts, not where it ends. The real questions come next. Why was the wrong setting available to apply? Why did two switches look the same? Why did the procedure allow a step to be skipped without anyone noticing?
What works:
→ looking for the barrier that failed, not only the person who was there
→ testing every corrective action against one question: does it make the error harder to repeat, or does it only remind people to be careful?
→ verifying effectiveness after closure, because an action that was implemented but never checked is just paperwork
ISO 9001 asks organizations to determine causes and review the effectiveness of corrective actions. Human performance practices, like those in the DOE Human Performance Improvement Handbook, start from the principle that error-likely situations are predictable and manageable.
People make mistakes. Systems decide whether those mistakes become events.