Dear SLF - CQ-CQ-CQ...
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Legalities - I transmit/receive using my ham radio call sign, with appropriate "air mobile" suffix.
The aircraft radios (HF radios) are fully capable to tune AM/SSB frequencies assigned to hams.
Radio hams who abuse of their R/T privileges are extremely rare.
They "chat" generally about radios, power, or best frequencies/propagation.
In case of emergencies, they often help. Was the case after the tsunami in Asia.
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Many radio officers in merchant marine also practice that hobby.
With my "air mobile call sign", many exchange QSL cards with me, to confirm.
Mine is a card with my call sign, a picture of an ARG 747...
Last year I got a QSL card from a Maersk containership. They were near Sri Lanka, I was near Cape Verde.
His call sign was "high-seas mobile"...
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In case of loss of aeronautical communications over high seas, I would try merchant marine or hams as last resort.
Ships have very sophisticated D/F capability. They could provide me with QDR on request.
In that case, I would use my airplane call sign, on marine or ham frequencies.
Living in apartment in Buenos Aires, they objected to install antennas on top of the apartment building.
My last antenna, was the window "screen"... not too efficient antenna...
So I sometimes practice the hobby from the airplane, in all legality and on proper frequencies.
xxx
In these days of worldwide internet... radio hams regret the "good old days".
Back then, I had a nice SONY shortwave receiver in my bags to listen to BBC news, worldwide.
Nowadays... is a laptop, to listen to radio stations, or watch TV news...
xxx
Happy contrails