Thanks Eckhard,
I did wonder because HF takes a lot of effort for not much reward but it is reliable even if hard to hear. My wife was an operator at Speedbird London back in the late 1970s , Along with more 'individualistic BA Captains there were Texan drawling Braniff pilots and JAL pilots who spoke poor English trying to give position reports as they trekked across USSR. None of them coming across very clearly on the rather aged , even then , SSB HF units