Root Cause Analysis
The investigation that establishes why something went wrong, rather than what went wrong. Five Whys suffices for most findings; deeper methods are warranted where the consequences are severe — the depth should match what is at stake.
The failure is not usually shallow analysis. It is analysis that stops at the person. "The technician did not follow the procedure" is a finding that feels complete and explains nothing — it does not say why the procedure was not followed, whether it was followable, or whether anybody has ever followed it.
A root cause you can act on is one that names a system: a specification, a training gap, a schedule that made the correct action impossible. If the conclusion is that somebody should try harder, the analysis has not finished.
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