To open the ram air inlet by selecting the RAM AIR switch ON, which switch must be in its normal guarded position?

To successfully open the ram air inlet by selecting the RAM AIR switch to the ON position, the ditching switch must be in its normal guarded position. This is essential because the ditching procedure is designed to protect the aircraft's systems by preventing water from flooding critical areas, which includes the ram air inlet.

When the ditching switch is not guarded, certain systems, such as the ram air inlet, may be inhibited to safeguard against potential flooding during water landings. This design ensures that the aircraft maintains its integrity during extreme situations and allows the crew to manage air and environmental conditions effectively.

In contrast, while the other switches control various systems within the aircraft, none of them directly influence the operation of the ram air inlet in the context mentioned. Having the ditching switch in the correct position is crucial for enabling the ram air inlet while maintaining safety and operational integrity during flight.