What term is used for the Common Traffic Advisory Frequency when none is available?

The term used for the Common Traffic Advisory Frequency when none is available is MULTICOM.

MULTICOM frequencies are designated for use when no specific traffic advisory frequency is assigned, allowing pilots to communicate with each other in non-towered airspace or at locations without a standard CTAF. It is particularly useful for making positional reports and coordinating traffic in the absence of a designated frequency, helping to enhance safety by providing a platform for pilots to announce their intentions and situational updates.

Other terms listed, such as UNICOM, CTAF, and FSS, refer to different communication protocols or services. UNICOM is typically used for non-governmental services at airports to provide information and services, while CTAF is the frequency specifically used for communicating at non-towered airports. FSS refers to Flight Service Stations, which are facilities providing various flight-related services but are not used for traffic advisories.