Contacted, next week Im due to land at least four "closed" airports, {after/before normall operating hours, not that there is any ATC or stuff at any time} no one on the ground, so if I call Mayday four times it will be OK? Somehow methinks that the other aircraft landing at these places might get a tad POd with us, not to mention our SAR folks.It seems to me that many who fly the big silver tubes these days have little or no clue about how much of the world operates,we recently had one divert to such an airport and insisted on calling "ground and tower ", didnt want to move unless someone spoke to him, seems he felt that 10,000ft of blacktop must have all this stuff, one of our destinations has around 100 IFR aircraft a day landing when "closed", so far none of us have bumped into each other, unlike a few controlled/open airports around here.Mind you it does require that the crews know where they are and can keep a plot in their head as to the location of the other folks, a skill that seems to be absent in many countries.Its worth noting that the worst ground collision in history took place at an "open/controlled" airport.