What happens when the AIR COND switch is in the BOTH position?

When the AIR COND switch is in the BOTH position, the aircraft utilizes both Auxiliary Power Units (APUs) to provide air conditioning and electrical power. This configuration allows the system to handle a full load of the aircraft’s environmental and electrical needs. By activating both APUs, the aircraft can efficiently distribute load and ensure that all systems requiring power operate effectively, especially during taxing, takeoff preparations, or when on the ground without the main engines running.

This setting maximizes operational capabilities by drawing on the combined output of both APUs, which is essential for maintaining environmental control in the cabin and powering other critical systems.