Last time I made a mayday I was going down into a wooded area. Last time I made a Pan I had an alternator failure.
In the former I was approaching a position whereby I MIGHT explode and die or might perform a textbook rough field landing. In the latter I might lose comms, some instruments and lights but at the end of the day I was going to land on a runway and not be on fire.
Its a mildly fuzzy area. My advice would be, a panicky MAYDAY can easily be downgraded to a PAN. The initial MAYDAY will give you EVERY helping hand available and all those hands will be glad to help. Nobody - and I know from 1st hand experience - will have a go at you for making that M call. The CAA will not give a toss. The local ATC Officer will not be peeved. Every professional and amatuer pilot on freq will be racking their brains for ways to help you. So make it if you're scared. Too many people have died for fear of sounding stupid or scared on the radio. Don't be one of them.
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