In Oz MDA (minimum descent alt) for circling is the minimum altitude for the instrument approach in IMC.
Once visual within the circling area you can legally come down to the lower OCA (obstacle clearance alt.) if required for example to remain visual. Our AIP elaborates and specifically states that descent below MDA can occur on base or downwind if required for normal descent to the threshold.
Once established on final descent below OCA can occur to the threshold.
What I want to know is; is it legal to bump your category UP to get a bigger circling area and more comfortable approach speeds at the expense of a higher MDA and OCA? It seems to be common practice here.
[This message has been edited by daytrader (edited 27 June 2001).]