Mandatory frequency airport
 |
An airport with a mandatory frequency (MF), mandatory traffic advisory frequency (MTAF) or air/ground radio (A/G) is an airport which does not have a control tower but still requires arriving and departing aircraft to communicate with other aircraft or a radio operator on a published frequency.
Mandatory frequency airports are rare in the
control tower. If there is a flight service specialist monitoring the frequency, the specialist will give pilots advisories about traffic, weather, and surface conditions, and may relay IFR clearances from en route controllers
, but cannot give clearances themselves.
In the United Kingdom, this type of airport is said to have an Air/Ground Radio service, using the callsign suffix "Radio". This is provided at airports that have a moderate level of VFR-only GA traffic.
Some examples of MF airports in Canada include
Kingston/Norman Rogers Airport and Kuujjuaq Airport
.