Pilot Error
A crew action or omission was a causal factor. Modern investigators treat it as a starting point, not a verdict. The useful question is why the action made sense at the time.
"Pilot error" is a category, not an explanation. Accident investigation moved away from it as a conclusion decades ago, because a report that stops at the crew's mistake produces no safety action: you cannot fix a person who is already dead.
What a good report does instead is trace the error back into the system around it: procedures, training, fatigue and rostering, cockpit design, checklists, the pressure of the schedule and the information available on the flight deck at that moment. On this site the category is used for navigation, and the case file itself carries the attribution the investigating authority actually made.
Related terms
Crew Resource Management: how a flight deck uses all the people and information available to it. CRM breakdowns are about communication, workload and authority, not stick-and-rudder skill.
The authority's formal statement of what caused the accident. The exact wording matters, and the archive quotes it rather than paraphrasing it.
The aircraft departs from normal controlled flight: a stall, an upset, or a control problem the crew cannot recover from.