What type of investigation occurs when an ACM fails to meet ATP requirements?

When an Aviation Crew-Member (ACM) fails to meet ATP (Airline Transport Pilot) requirements, a commander-directed investigation is initiated. This type of investigation is formally overseen by the aircraft's commander and focuses on assessing the circumstances surrounding the ACM's performance issue. The commander has the responsibility to ensure safety and operational integrity, hence they will direct the investigation to uncover any contributing factors and to determine the appropriate corrective actions.

In contrast, a flight review typically evaluates an individual's proficiency and up-to-date knowledge of regulations and operating standards, but it does not focus specifically on failures related to ATP requirements. An executive investigation usually involves higher-level scrutiny, typically addressing systemic issues rather than individual performance. A peer review might provide feedback or assessment among colleagues; however, it lacks the formal authority and structure required in situations when ATP standards are not met. The commander-directed investigation is the structured approach necessary to ensure accountability, safety, and adherence to aviation standards.