Who is responsible for deciding if operational circumstances permit controlled rest?

The decision regarding whether operational circumstances permit controlled rest is the responsibility of the captain. This is due to the captain's leadership role and comprehensive understanding of the aircraft's operation and the current flight situation. The captain must assess factors such as the current weather conditions, air traffic control requirements, and any potential emergencies or disturbances.

In situations where controlled rest could be beneficial—such as mitigating fatigue—the captain considers these operational factors holistically. By having the authority to make this decision, the captain ensures the safety of the flight crew and passengers, aligning with the protocols that prioritize safety and operational efficiency.

The first officer, while a key member of the cockpit team, operates under the captain's leadership and may provide input but does not hold the final authority in this matter. Flight attendants play an essential role in ensuring passenger safety and comfort, but they are not involved in dynamic cockpit decision-making. The ground crew primarily deals with pre-flight and post-flight operations, not in-flight decisions.