Remember when a CTAF was a cheese-shaped volume of air with an upper limit of 3000 feet and a radius of 5 nautical miles around the airport? Not all that long ago, was it? There were specific radio calls that had to be made. It was all pretty clear and easy to understand, and as far as I recall it worked rather well.
Then we had the "new airspace procedures" and operations around non-towered aerodromes. A CTAF could be a CTAF or a CTAF(R). One needed a radio to be carried, the other permitted entry without a radio. The dimensions of the CTAF area changed as well. It became a cylinder of air with no height limit, with a requirement that aircraft be listening to the CTAF frequency "by 10nm". Mandatory radio calls were documented and we all started cluttering up the frequency with call after call after call.
Realising the situation had gone beyond a joke, CASA decided to remove mandatory radio calls altogether and replace them with the catch-all proviso that pilots needed to make calls whenever they felt it necessary to do so in the interests of safety. Oddly enough, most pilots continued making most of the calls that had been mandatory - basically because they were genuinely useful.
Well, with effect from 28th June 2012, a CTAF has been redefined yet again, and now it has a defined upper limit. But the upper limit depends on what airspace lies above the area enclosed by the CTAF. The "by 10nm" requirement remains unaltered - for the time being. Another point; it is unclear whether we are to use the term CTAF now, or use the term NTA (non-tower aerodrome).
The new upper limits are as follows:-
i) if there is class G airspace above the CTAF then the CTAF upper limit is 5000 feet.
ii) if there is low-level class E airspace above the CTAF, then the upper limit is 8500 feet.
iii) if there is a control zone above the CTAF then the upper limit is the base of the control zone.
Instructors will doubtless relish the task of re-training existing student pilots in the new requirements. New students will just accept this as the word of God - until someone with not enough to do in the office of airspace reform in Canberra decides to change it yet again. Naturally all the training manuals, exams etc will be immediately re-written to reflect the changes.
The May-June 2012 edition of "Flight Safety" magazine detailed these changes, but my attention was drawn to it by an article in "Australian Aviation", July 2012 issue, page 84, sub-titled "The massaging of non-tower aerodromes (NTA) procedures continues."
I think the word "massaging" is rather perfumed, actually. I'd be using a far less euphemistic term.
