The airline said the facility would house eight flight simulators and train 4,5000 new and current pilots – including those set to fly Project Sunrise direct flights from London to Sydney.
The airline said the surprise expansion was due to a huge increase in online shopping, spurred on by the pandemic.
Engineers across the Qantas Group have voted overwhelmingly in favour of taking protected industrial action, including strike action, which could start as early as Monday.
The airline has pledged to increase incentives to boost pilot retention, as well as increase recruitment and training efforts, after a number of its pilots left the airline to pursue roles overseas.
The new change will come into effect from 21 August, and apply to all Qantas new and existing bookings that include a domestic connection ahead of an outbound international flight.
Air New Zealand has started reviving the first of its Boeing 777-300s that were placed in storage in the California desert after nearly 700 days, ahead of its planned return to passenger service.