Policy is that 121.5 is monitored on the other radio unless using it to obtain the ATIS for destination, talk to handling / ops or getting the volmet.
However, I can guarantee that when "
The other day they were calling for an a/c on the 121.5 for many minutes" is encountered we deselect that radio on the intercom until we find that peace reigns.
I am sure that everyone else within 250nm (except the one you are calling) is doing the same.
Problem is that you do that for 10 minutes and for 5 of those minutes you are crossing with some airfirce base in Germany calling something else and then we have to get the ATIS and then we are 50nm south east of Paris and in range of the "Practice Pan brigade" and guess what, we end up flying from Nice to London trying to listen on 121.5 but finding that it is impossible due to the constant chatter
from ground stations
I use "chatter" to include ACC's trying to contact silent aircraft, airfirce bases doing radio checks etc because it is a reason for deselecting 121.5 since when PNF (PM) the primary outside communication task is to monitor and respond to calls on the ACC/APP/TWR frequency. Monitoring 121.5 is secondary and can't be allowed to hamper the first.
Have you ever considered the posibility that they can't hear you on the ACC frequency because they are hearing transmissions from a ground station other than you on 121.5 and when you call on 121.5 this other ground station is blocking you?
What is the DOC of your 121.5 at say 40,000ft and how many other ground stations overlap that DOC - lots and lots if you are in central Europe - and most of them can not hear the other's transmissions and so don't know (or in the UK case 'care') if thay are blocking your transmissions.
So before you go blaming the aircrew, remember that we hear every idiotic waaaaaaaassssssssuuuuuuupppppppppp on 121.5 with hundreds of miles, we hear every ground station within a similar distance - but you don't and therefore are not best placed to decide if you transmission has nay chance of success.
There are also plenty of places in Europe where VHF coverage is poor - parts of Italy fro example - hard to believe that between Corsica and Rome the coverage at 300+ can often be quite poor.
No point in giving me the xxx123 we have called you several times. If I had heard you I would have responded!! We don't intentionally ignore direct clearances / short cuts!!
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On a side note - I never adjust the volume of the radio other than to make it comfortable i.e. I never turn it down fully. If I don't want to hear what is going on I will de-select it on the intercom. I have seen so many pilots turn down the volume and then forget that while the light on the intercom says you are listening to the freq, you are not going to hear anything.