Regulation 100

a public address system; and

a crew member intercom system.

must be capable of operation independent of the crew member intercom system required under paragraph (1)(b), with the exception of the handsets, headsets, microphones, selector switches and signalling devices;

must be accessible for immediate use from each of the flight crew member stations in the flight deck;

must have a microphone or equivalent installed for each required floor‑level passenger emergency exit that has an adjacent cabin crew seat, which is readily accessible for immediate use by the seated cabin crew member; and

must be understandably audible at all times at all passenger seats, lavatories, cabin crew seats and work stations.

must be capable of operation independent of the public address system required under paragraph (1)(a), with the exception of the handsets, headsets, microphones, selector switches and signalling devices;

must provide a means of two‑way communication between all members of the flight crew;

must provide a means by which a crew member may communicate with another crew member at the flight deck, each passenger compartment and each galley not located on a passenger deck;

must be accessible for immediate use from every flight crew member station in the flight deck;

must be accessible for immediate use from at least one cabin crew member station in each passenger compartment;

must be accessible for use at enough cabin crew stations so that all floor‑level emergency exits in each passenger compartment are observable from a station so equipped; and

must have an alerting system that —

incorporates aural or visual signals for use by any crew member;

provides a means for the crew member who is receiving a call to determine whether it is a normal call or an emergency call; and

provides a means of two‑way communication between ground personnel and any 2 flight crew members in the flight deck when the aeroplane is on the ground.