Hi TP,
I'm not a planning consultant or lawyer, but I think it might be slightly different here. A planning decision here would be made by a panel that is a creature of local government, with the air of a slight degree of independence because some members of the panel are neither councillors nor council staff. If an applicant to council isn't happy with a council or panel decision, they can go to the ERD (environment, resources and development) court which can and will examine all aspects of the case. At least those presented in evidence to it. I've seen ERD courts give very short shrift to councils, and I know from my own experience that councils in SA are sometimes wary of going to ERD because they know they might lose.
There is also the Development Assessment Commission, which has decision-making functions that often seem to overlap with those of councils. DAC, another creature of state govt, arising out of the development act 1993, has roles in assessing non-complying developments, which the airfield probably is. I've seen DAC give rulings that run very counter to the views of councils. ERD could I think re-examine a DAC decision just like it could a council decision.
Appeals of these decisions could be made to the SA supreme court which functions I suspect like the Vic. equivalent.
Planning law in SA is complicated, unwieldy, expensive and slow. And yes, some lawyers probably make a good living out of this, however someone like the airfield could use this against the council, who won't want to spend money fighting a case they might lose.
My guess is the 1992 LMA will carry more weight with DAC and ERD than the 1977 document. No doubt someone will correct me if I'm wrong.