I'm ex RAAF, not aircrew though. I'm thinking you will need year 12, and high marks in maths for starters. There are a few interviews along the way as well (selection boards). The military selection process is quite long and involved - psyche testing, fitness testing etc. All ADF positions require aptitude testing, whch is something you can't really practise for. The Aircrew selection process is very competitive. Hope this helps:) ps civilian flying qualifications would be an advantage - it would show aptitude and ability.