Communications: Difference between revisions

Airports without a control tower (or other air-traffic facility) normally publish a standard frequency for pilots to communicate with each-other: in the US, for example, this is called the _Common Traffic Advisory Frequency_ (CTAF), and it in Canada, it is called _Aerodrome Traffic Frequency_ (ATF). When making calls on the CTAF, the pilot addresses them to _Traffic_ (e.g. "Ogdensburg Traffic, Grob 123 downwind for runway 09").

These airports may also have a facility that is staffed by someone who is not an air-traffic controller or flight-services specialist (for example, a dispatcher at a flight school, or a fuel operator at an FBO). These people cannnot give official clearances, but they can often provide a *field advisory* including the current temperature, wind, runway surface condition, fuel availability, and any known traffic, and can also provide radio checks and similar services. The frequency for obtaining the advisory is called the UNICOM (_Universal Communications_).  

Most of the time, the CTAF and UNICOM frequencies are the same, but they can occasionally be different. The pilot should address only specific requests to "UNICOM" (e.g. "Brockville UNICOM, this is Cessna ABC requesting the field advisory."). All position reporting should be addressed to "Traffic" over the CTAF (if different from the UNICOM).

Note that many airports have control towers that are not open 24/7. When the control tower is closed, the tower frequency will typically become a CTAF, and pilots do their own position reporting.

In Canada and some other countries, when talking over the CTAF/ATS is required, it is referred to as the MF (_Mandatory Frequency_), and will often be monitored by a flight-services specialist. The MF is often for limited hours, and outside of those, it also becomes a CTAF. If there is an FSS specialist monitoring the MF, then the pilot will address calls to "Radio" (e.g. "Kingston Radio, Cherokee FBO is 10 miles north, requesting the active runway."); otherwise, the pilot will address them to "Traffic", as with the CTAF.