There are two frequencies that all pilots know by heart: 121.50 and 123.45. The first one is the emergency frequency that can be used at any time when safety of the flight is endangered. The second one… well… how to describe it… it’s piece of ambiguity.
ICAO Annex 10 states that “123.45 Mhz shall be designated for use as an Air-to-Air communications channel to enable aircraft engaged in flights over remote and oceanic areas, out of range of VHF ground stations, to exchange necessary operational information and to facilitate the resolution of operational problems“. As all ICAO documents, this is a recommendation, which can be overruled by local laws.
Most of Europe is not continental nor remote, but several pilots do use it as a chat frequency. The UK NATS published an AIC (16/2003 Pink 53) to remind pilots that this frequency is not for general use by pilots, as it is officially allowed to some helicopters companies. Moreover using 123.45 in a UK FIR can result in interference at other places.
Germany defined 122.80 as a “chat frequency”, and 123.45 is also used by Bangalore Tower (India). When googling it, I found many references mentioning this frequency being recognized as air-to-air frequency in the US, but no official confirmation. Finding the official chat frequency (if any) in the national AIPs or in the standardized Jeppesen manuals is not easy.
With such a complicated situation (referred to as a “mess” by some NATS collaborators), it’s not surprising that some urban legends exists about it in the flying community. The following dialog supposedly happened in Frankfurt:
“US-Airforce C-130: TWR tell 747 in front of us to call us on 123.45
TWR: XX777 would you mind calling C-130 on 123.45?
xx777: Sorry TWR, we do not talk on 123.45, we are professional pilots
US-Airforce C-130: OK, TWR tell those professional pilots they still have the gear pins in!”
(The pins are security locks put on ground to avoid unwanted retraction)
For more information see the, Handbook on Radio Frequency Spectrum Requirements for Civil Aviation.
Now, I’d like to know what is your personal use of 123.45? Comment below and let us know how you use it!