What position should the manual hydraulic backup selector be in for flight operation?

The correct position for the manual hydraulic backup selector during flight operation is in the "Flight" position. This setting ensures that the hydraulic system is fully operational and can effectively manage the aircraft's control surfaces and systems that rely on hydraulics for functionality. In the "Flight" position, the primary hydraulic systems are engaged, allowing for normal operation and enhancing the aircraft's response to pilot inputs.

Selecting "Flight" also means that the system has access to the normal hydraulic pressure, which is critical for maintaining safety and performance during various phases of flight, including takeoff, cruising, and landing. In contrast, other settings such as "Auto," "Off," or "Standby" would not support the necessary hydraulic pressures and functionalities needed for safe flight operations, potentially limiting the aircraft's performance or making it inoperable in critical situations.