Interphone Code 1 is used for which communication?

• A. Interphone to flight deck
• B. Public Address (PA) to main cabin
• C. Interphone to AFT Cabin
• D. Public Address (PA) to FWD cabin

Answer: (B)

The key idea is how aircraft communications distinguish between crew-to-crew calls and passenger announcements, and how codes pick the destination. Interphone is used for calls between crew, often targeting a specific area (flight deck, aft cabin, etc.), while Public Address is for announcements to passengers. A code value is assigned to route the message to a particular system and zone.

Using code 1 directs the Public Address system to the main cabin, so a crew member can make an announcement to passengers seated there. This is the best fit because it explicitly targets the main cabin with a PA broadcast, rather than calling the flight deck or a specific cabin section via interphone.

The other routes involve different communication paths: interphone calls to the flight deck or to the aft cabin, or a PA to the forward cabin. Those would be used with different codes or calling methods, not code 1.