Qantas has signalled it will sack 300 maintenance engineers and staff at Avalon Airport by next year, and move all its heavy maintenance work to Brisbane.
The airline announced on Tuesday it would review the future of Avalon, where its shrinking fleet of Boeing 747 aircraft is maintained.
The review, to be completed by the end of October, follows an earlier round of sackings at Avalon.
Last year, 263 engineering and maintenance jobs at Avalon went, with the work moved to Brisbane.
The jobs to be reviewed over the next six weeks are those of all the remaining maintenance staff.
Qantas domestic chief executive Lyell Strambi said on Tuesday the Avalon maintenance facility had no scheduled work booked in from March.
"In fact, there will be no scheduled maintenance for the equivalent of five months each year for the next four years, starting in March," Mr Strambi said.
Among the maintenance engineers who could lose their jobs once the review is completed is Rob Cavanagh. The 41-year-old has worked for Qantas at Avalon for 14 years. He said staff there were trying to remain positive about their chances of keeping work. "But the long-term effect probably won't be positive," he said.
Mr Cavanagh, who is also a union delegate, said engineering staff had been under stress because of the uncertainty surrounding the future of Avalon, which opened in 1998. "It might be some relief when we do get a final date. If it is a final date - we're remaining optimistic until we hear otherwise."
But Australian Workers' Union Victorian secretary Ben Davis said the "review" of heavy maintenance at Avalon was "code for closure and another move towards offshoring". "We know from experience that when Qantas does a review, jobs go," Mr Davis said.
Qantas also last year shut its heavy maintenance base at Melbourne Airport in Tullamarine.
The expected layoffs at Avalon, which Qantas has flagged since the middle of last year, come as a new generation of aircraft that require much less servicing than older planes enter service.
A decade ago, Qantas had 36 747s in the sky, compared with 15 today. Within three years, that number will fall to just 10.
But unions have argued that the airline is also seeking to drive down maintenance wages by sending what remaining 747 work it can overseas or to outsource it.
Steve Purvinas, federal secretary of the Australian Licensed Aircraft Engineers Association, said that because Qantas had reduced its 747 fleet, there would not be enough work to keep staff at Avalon busy. Mr Purvinas said he expected Qantas to conduct a genuine review. "And it will be our job as a union to offer flexible work practices that will make it cost-effective" to find maintenance staff at Avalon work.
Avalon is close to Geelong, which has experienced a rash of heavy job losses in the past 12 months, with Ford to close its plant there in 2016, costing 510 jobs, and Target slashing 260 jobs in June. Shell is also trying to find a buyer for its Geelong refinery, and 450 jobs could go if it fails.
Geelong City acting mayor Bruce Harwood called on Qantas to retain jobs at Avalon, saying any reduction would be a disappointment.