Pilots use the tower frequency to coordinate their arrivals and departures safely, giving position reports and acknowledging other aircraft in the airfield traffic pattern.
UNICOM is a licensed non-government base station that provides air-to-ground and ground-to-air communication, and may also serve as a CTAF when in operation.
MULTICOM is a frequency allocation without a physical base station that is reserved as a CTAF for airports without other facilities.
There are also CTAF(R) landing strips which require the aircraft intending to enter the area of operation to be fitted with a radio.
[2] However, most gliding clubs use the Glider Ground Station Common Field Frequency, currently 129.975 MHz.