AIM Text
Frequency use
- The following listing depicts UNICOM and MULTICOM frequency uses as designated by the Federal Communications Commission (FCC). (See TBL 4-1-2.)
TBL 4-1-2
Unicom/Multicom Frequency UsageUse
Frequency
Airports without an operating control tower.
122.700
122.725
122.800
122.975
123.000
123.050
123.075(MULTICOM FREQUENCY) Activities of a temporary, seasonal, emergency nature or search and rescue, as well as, airports with no tower, FSS, or UNICOM.
122.900
(MULTICOM FREQUENCY) Forestry management and fire suppression, fish and game management and protection, and environmental monitoring and protection.
122.925
Airports with a control tower or FSS on airport.
122.950
NOTE-
1. In some areas of the country, frequency interference may be encountered from nearby airports using the same UNICOM frequency. Where there is a problem, UNICOM operators are encouraged to develop a “least interference” frequency assignment plan for airports concerned using the frequencies designated for airports without operating control towers. UNICOM licensees are encouraged to apply for UNICOM 25 kHz spaced channel frequencies. Due to the extremely limited number of frequencies with 50 kHz channel spacing, 25 kHz channel spacing should be implemented. UNICOM licensees may then request FCC to assign frequencies in accordance with the plan, which FCC will review and consider for approval.2. Wind direction and runway information may not be available on UNICOM frequency 122.950.
- The following listing depicts other frequency uses as designated by the Federal Communications Commission (FCC). (See TBL 4-1-3.)
TBL 4-1-3
Other Frequency Usage Designated by FCCUse
Frequency
Air‐to‐air communication
(private fixed wing aircraft).122.750
Helicopter air-to-air communications; air traffic control operations.
123.025
Aviation instruction, Glider, Hot Air Balloon (not to be used for advisory service).
123.300
123.500Assignment to flight test land and aircraft stations (not for air-to-air communication except for those aircraft operating in an oceanic FIR).
123.4001
123.45021This frequency is available only to itinerant stations that have a requirement to be periodically transferred to various locations.
2Mobile station operations on these frequencies are limited to an area within 320 km (200 mi) of an associated flight test land station.
Source: FAA Aeronautical Information Manual · current edition · paragraph 4-1-11.
Research Notes
AIM 4-1-11 lists Designated UNICOM/MULTICOM Frequencies — the FCC-allocated airport advisory frequencies.
UNICOM frequency table (common allocations):
- 122.7, 122.8, 122.725, 122.975, 123.0, 123.05, 123.075 MHz — common UNICOM frequencies at airports without an operating control tower. The specific airport's UNICOM is published on the sectional and in the Chart Supplement.
- 122.95 MHz — UNICOM frequency at airports WITH an operating control tower (when used for non-ATC services like FBO comms).
- 122.85 MHz — UNICOM at heliports.
- 122.9 MHz — MULTICOM (used at airports without UNICOM or tower — pure self-announce frequency).
UNICOM vs MULTICOM: UNICOM is a private aeronautical advisory service licensed to a specific airport (typically the FBO or airport manager). MULTICOM is a non-specific advisory frequency used when no UNICOM is licensed for that airport. Functionally, both serve the same self-announce role — pilots use them as CTAF for self-coordination.
The CTAF designation: Each non-towered airport has ONE designated CTAF. The CTAF may be a UNICOM frequency, a MULTICOM frequency, or (at part-time tower fields) the tower frequency itself when the tower is closed. Always check the Chart Supplement entry for the airport's specific CTAF.
Reference: FCC Part 87 (Aviation Services); AC 90-66B; FAA Chart Supplement.