I've been looking for an answer to this for the past couple of hours and can't find anything on the matter. (Yes, I've read this What radio frequencies are used for intercom in formation flying? , but it didn't answer my question, as I'd like to know about frequencies that are not in use by any authorities or organisations and are not used for anything official, such as search and rescue).

A pilot mentioned to me she "created" frequencies to talk in private with her mate (air-to-air interpilot). I found one link that says pilots sometimes use unallocated frequencies to chat , so I assumed she meant that, but I've just read on AOPA that all 760 channels available in the VHF aviation band are actually allocated (I'm assuming in the USA, as the reference is an FAA circular) even if some are not used at all times.

So, can you "create" a private frequency? If I'm right to assume that that makes no sense, can you join a private frequency (do they exist??) or use an unallocated one to chat privately? In case it's the latter, how does that work if all frequencies are allocated already (or is that just in the USA)?

Thanks a lot for your help

  • $\begingroup$ There are frequencies set aside for air to air conversations but they are not private. Any other person with a radio tuned to that freq can listen or talk. $\endgroup$ – acpilot Apr 30 '18 at 3:15
  • $\begingroup$ Private assumes that the conversations are not comprehensible for anyone else on that channel. This would require encryption on both ends. If you can manage that, then it doesn't matter who else is listening on the frequency. Is this what you are aiming for? $\endgroup$ – Burhan Khalid Apr 30 '18 at 6:37
  • $\begingroup$ The best you can practically get is to use (share with everyone) a unlicensed frequency, and encode/encrypt it in a robust way so that sharing is not a problem, just like how WIFI and bluetooth does it. $\endgroup$ – user3528438 Apr 30 '18 at 14:37
  • $\begingroup$ I don't think this answers your question, but 122.75 is designated as the fixed wing air-to-air frequency and 123.025 for helicopters. While they are to be used for the purpose you outline, though without any suggestion of privacy. $\endgroup$ – J Walters Apr 30 '18 at 19:17
  • $\begingroup$ When I was earning my licenses in 1975, the FAA provided each of the flight schools (4-5) at the airport I flew out of, a discreet frequency and all training aircraft where required to monitor their FBO base station frequency once they were out of the pattern. I assume this provision is still available in some form. $\endgroup$ – jwzumwalt Apr 30 '18 at 19:58

Every frequency is allocated somewhere, in fact the same frequency will be used over and over throughout the world. This works because air band radios are relatively short range, about 200nm at best, so all you really need to do is find a frequency that isn't used anywhere near you and tune to that. This is what formation or group flights do.

That will not be private in the sense that it cannot be overheard, anyone with an air band radio can listen in. It will also not be private in that only you could use it, again anyone could tune into the same frequency for the same purpose. Formations often have secondary frequencies to tune to in these cases, but it's rare they need them.

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Within the United States the designated air-to-air frequency intended for this purpose is 122.75 MHz. If you use a different frequency you could interfere with some other aviation band communications somewhere else within range of your transceiver. Do not do this.

See the Aeronautical Information Manual (AIM) 4-1-11 in table 4-1-3 for other related frequencies but 122.75 is the standard go-to.

Tbl 4-1-3

While this is indeed aviation-related and the FAA publishes documents listing frequencies, allocation and reservation of radio frequencies is handled by the FCC, not the FAA. It is noteworthy that while some frequencies are agreed upon by international treaty (read: ICAO), each member country’s government is responsible for frequency allocation within that country. In the U.S. that’s the FCC.

Source: I’m a flight instructor.

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  • $\begingroup$ The FCC allocates the overall band but the FAA has a department just for managing specific station frequencies within air band. The FAA department is "Spectrum Engineering AJW-1C" and they handle both navaid volumes and comms allocation along with the help of the flight inspection department.(flight check maps the actual signals in use) The FCC and FBI assist AJW-1C when there are issues that need investigation like artificial interference. $\endgroup$ – Max Power yesterday

123.45 is commonly used as an (unallocated) air-to-air frequency, although depending in your location it might not be officially sanctioned

You may use that for chat or formation flying, but it will definitelly not be private

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  • 2
    $\begingroup$ Within the United States, 123.45 MHz is authorized to be used only non-governmental flight test operations, and is not to be used as an air-to air frequency. However, over remote and oceanic areas, out of range of ground stations, it is designated as an air-to-air frequency. See FAA Order 6050.32. See also the FCC regulations for more information on frequency designations and penalties for misuse. Note that 122.75 is designated as the fixed wing air-to-air frequency. $\endgroup$ – J Walters Apr 30 '18 at 19:14
  • $\begingroup$ Huh... That sounds like it should have been an answer... $\endgroup$ – jwzumwalt Apr 30 '18 at 19:49

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