Chadzat asks " Now what happens when you have a new type to Australia? "
Answer: You do what has worked perfectly well before.
Here is a rough list of turbine powered aircraft successfully introduced into australian airline service without the "assistance" of FOUR year 457 visa holders.
A300, A310, A320-21, A330, B707, B717, B727, B737-200, B737-300-800, B747-200-300. B747-400, B767, B777, DC9, MD82-83, E170/190, F27, F28, F50, F70-100, ATR42, BAe146, RJ70, L188, Dash8 100-400, Saab340, Metro3, CRJ, B1900, Brasilia, J31, J41, Viscount. etc etc
All introduced by australian pilots without incident or accident.
We don't need long term 457 visa holders to introduce "new" aircraft. The record shows we have been successfully doing this for decades.