Further to DENABOL's quote of
Ben Sandilands’ Plane Talking blog, and the downgrade by FAA of India to a second tier aviation authority, the downgrade is by FAA but ICAO provides a handier tool to compare safety capabilities at http://www.icao.int/safety/Pages/USOAP-Results.aspx.
Looking at the results of ICAO audit of Indian DGAC versus results for CASA, it’s clear that both perform better than global average. That’s not surprising because ICAO average is pulled down by many small states that have no pretensions of ever flying to the US. Note that India ranks better than Australia against half of audited performance criteria. Note too that ICAO last audited Australian in 2008 whereas India was reaudited in 2012.
So Australia’s vulnerability hinges on whether it has improved over past five years. Make your own judgement.