Triangulation. The only ONLY reason CASA has just wasted up to half a million dollars on two years of bumpf and meetings and documentation on the giant CTAF is as a result of the frequency boundaries being put back on the charts.
NAS made it clear that the frequency boundaries were being removed and did this..
Why were they put back on? So pilots could use the old FS type system and use radio arranged separation.
That was a directed traffic system where IFR and VFR flew at the same altitudes and separated by radio. No other country had this system as it is incredibly expensive.
As Chairman of CAA I pushed for and achieved the introduction of the North American system. IFR and VFR then flew at different levels. As they do now.
Pilots attempted to keep the old with the new.
Once you put the frequency boundaries on the charts you give a clear message that they are there so VFR pilots call and answer IFR aircraft while en route. Then you have to bring in hard and prescriptive dimensions on where you change frequency.
That’s where it becomes impossible.
But just as it looks as if we will never be able to user safer and better nuclear power due to fear mongering and resistance to change it may be the same in moving to a simpler international airspace system.