When is the interphone system activated in COLD mode?

The interphone system in COLD mode is activated only when the key switch is activated. This mode is designed to conserve power and is a default setting when the aircraft is not in an operational mode. By requiring the key switch to be activated to power the interphone system, the design ensures that the system is only operational when necessary, thereby maximizing battery life and preventing unnecessary power drain.

In this mode, the interphone system may not function if the key switch does not provide power, reflecting a safety precaution to reduce distractions during critical phases of flight.