“Operator failed to follow procedure” is an observation, not a root cause.
A practical route
Write the problem as a measurable event. Build a timeline. Separate facts from hypotheses. Use a fishbone to widen the search, then apply 5 Whys only to evidence-backed branches. Validate the cause with a small change or record sample, then check effectiveness.
What good looks like
The process is visible at the point of work. The person doing the task knows the current requirement, the person approving it can see objective evidence, and the owner can tell whether the control worked. Keep the record small enough to complete in the moment: requirement, result, exception, owner, date, and next decision.
The failure mode to avoid
Do not solve a recurring process problem with a longer form alone. Watch one real job, find the handoff that breaks, and change the workflow or responsibility. Then sample the next few records to confirm the change stuck. The output should be a record someone else can verify. Use the nonconformance module. to keep that chain together.