Etrust. The CTAF system that operated with complete safety from the introduction of NAS on the 27 TH Nov 2003 for 3 months until Airservices undermined the whole proposal when they printed and published a “ wind back” map with the 1960s frequency boundaries on them.
This is how the proven system works.
When en route if in the airspace normally used for the approach and departure airspace of an aerodrome monitor and announce if necessary on that aerodrome ctaf.
Too simple I know. No dimensions required.
Then bring in the next stage of NAS where busy RPT aerodromes like Ballina have E dropped to a low level coupled with the wide scale introduction of non prescriptive no cost US style unicoms. It will happen one day. Just need a few of the concrete minded to retire or die