When can crew rest begin?

Crew rest can begin after the last official duty is completed because this timing ensures that all responsibilities and commitments related to the mission are finished before rest begins. This practice is important for ensuring that crew members are adequately rested and prepared for future tasks or flights, as it allows them to recharge fully without lingering obligations that may distract or detract from their ability to rest effectively.

This definition of crew rest aligns with aviation safety regulations that emphasize the need for adequate rest periods to maintain alertness and performance levels for crew members, thereby promoting safety in flight operations.