I regard an effective equitable education system as one that results in high level outcomes for learners, i.e. a good standard of skills that will serve the person well in their future life, AND does not create unnecessary impediments to any learners.
To expand the intent of the question - I regard the extant education system in Australia to yield high outcomes but only to a proportion of learners. Those learners who begin in the education system with a deficit of any kind, either skills, cognitive, psychological,
or social have a much higher probability of 'opting out' and 'dropping out' and consequent reduced opportunities for educational attainment.
The characteristics I am after are design parameters stated as specifically as possible, e.g. an assessment system that does not define learners as winners or losers, pass or fail, would be specific and an assessment system that measures students' progress along a continuum of standards, would be more specific, etc.