In what mode does the pilot manually operate the outflow valve?

The pilot manually operates the outflow valve in manual mode. In this mode, the pilot has direct control over the outflow valve's position, allowing them to adjust cabin pressure as needed based on flight conditions and operational requirements.

Manual mode is essential for situations where the automatic systems may not sufficiently manage the cabin pressure, or when fine-tuning is required to maintain optimal comfort and safety for the crew and passengers. In this mode, the pilot can respond more directly to changing conditions, such as rapid ascent or descent, necessitating immediate adjustments that automatic systems may not accommodate quickly enough.

The other modes, such as automatic and emergency, do not involve direct manual control by the pilot over the outflow valve. In automatic mode, the system manages the outflow valve without pilot intervention, adjusting automatically based on pre-set parameters. Emergency mode is usually activated under specific critical scenarios where automated systems are failing or inadequate, and control may still not be directly assigned to the pilot in the same fashion as in manual mode.