A UNICOM (universal communications) station is an air-ground communication facility operated by a non-air traffic control private agency to provide advisory service at uncontrolled aerodromes and airports and to provide various non-flight services, such as requesting a taxi, even at towered airports. It is also known as an aeronautical advisory station. The equivalent European/ICAO service is known as (aerodrome) flight information service, abbreviated as AFIS or FIS.
Description
UNICOM is employed at airports with a low volume of general aviation traffic and where no control tower is active. UNICOM stations typically use a single communications frequency. Some airfields always offer UNICOM service while others revert to UNICOM procedures only during hours when the control tower is closed. Under this protocol, aircraft may call a non-government ground station to make announcements of their intentions. Pilots who join the frequency later can request field advisories, which may include "weather information, wind direction, the recommended runway" and any previously reported traffic.
In some cases, the ground station is not staffed, and attempts to communicate will, of course, receive no acknowledgement. During these times, pilots self-announce their position and/or intentions over the CTAF frequency, which is often the same as the UNICOM frequency. When a part-time UNICOM station is located on the same airport as a part-time control tower, the same frequency will be used by both ground stations to avoid confusion. Many UNICOM stations are operated by a fixed-base operator (FBO), and it may be possible to request services such as fuel trucks, taxi service from the airport, outgoing phone calls, and others.
Frequencies
The actual frequency used at any particular airport can be found on the relevant sectional, terminal area chart or in airport directories, such as the Canada Flight Supplement.
United States
In the United States, radio frequencies made available by the Federal Communications Commission for use as UNICOM are:
Airports with an Air Traffic Control tower or FSS (Alaska only) on the airport. 122.950 MHz
Airports without an Air Traffic Control tower or FSS on the airport. 122.700 MHz 122.725 MHz 122.800 MHz 122.975 MHz 123.000 MHz 123.050 MHz 123.075 MHz
Canada
In Canada, the radio frequencies assigned for UNICOM are:
122.700 MHz
122.725 MHz
122.750 MHz
122.775 MHz
122.800 MHz
122.825 MHz
122.950 MHz
123.000 MHz
123.300 MHz
123.350 MHz
123.500 MHz
See also
CTAF
MULTICOM
References
"Chapter 4: Air Traffic Control," Airman's Information Manual (Washington, DC: Superintendent of Documents, 1999).