AIM Text
- FSSs and Supplemental Weather Service Locations (SWSL) are allocated frequencies for different functions; for example, in Alaska, certain FSSs provide Local Airport Advisory on 123.6 MHz or other frequencies which can be found in the Chart Supplement. If you are in doubt as to what frequency to use, 122.2 MHz is assigned to the majority of FSSs as a common en route simplex frequency.
- Certain VOR voice channels are being utilized for recorded broadcasts; for example, ATIS. These services and appropriate frequencies are listed in the Chart Supplement. On VFR flights, pilots are urged to monitor these frequencies. When in contact with a control facility, notify the controller if you plan to leave the frequency to monitor these broadcasts.
Source: FAA Aeronautical Information Manual · current edition · paragraph 4-2-14.
The short answer
This AIM section is FAA advisory guidance on VFR radio communications with Flight Service. It explains FSS and SWSL frequency allocation—such as Local Airport Advisory on 123.6 MHz in Alaska—and identifies 122.2 MHz as the common en route simplex frequency assigned to most FSSs. It also covers monitoring recorded VOR voice broadcasts like ATIS, supporting Part 91 communication practices.
Research Notes
Common Questions
What frequency should I use if I'm unsure how to reach an FSS en route?
The AIM advises that if you are in doubt as to what frequency to use, 122.2 MHz is assigned to the majority of FSSs as a common en route simplex frequency.
How should I make an initial callup to Flight Service?
What should I do before leaving the control frequency to monitor a broadcast?
Certain VOR voice channels carry recorded broadcasts such as ATIS, and on VFR flights pilots are urged to monitor them. When in contact with a control facility, notify the controller if you plan to leave the frequency to monitor these broadcasts.