Qantas is considering alterative options after admitting non-stop London-Perth flights will not return until at least April 2022.
International flights are still on track to gradually restart from December 18 onwards when Australia is expected to have reached an 80% vaccination threshold.
But the airline will temporarily re-route the flagship London-Perth route due to the latest Western Australia border restrictions.
Darwin is being assessed as an alternative to provide a daily link between London and Melbourne.
The carrier will fly London-Singapore-Melbourne if the service is not able to operate via Darwin.
Qantas has used Darwin as a hub for repatriation flights to various destinations across Europe, Asia and the Middle East over the past 12 months.
Qantas group chief executive Alan Joyce said: “It’s great to see plans firming up for some domestic borders opening given the success of the national vaccine rollout.
“We’re now planning to ramp up flying between Melbourne and Sydney, which is usually the second busiest air route in the world, almost a month earlier than expected.
“There are also a lot of regional destinations that will open up for the first time since June, which is great news for tourism as well as family and friends who can’t wait to see each other again.
“Get ready to see some emotional reunions at airports from late-October onwards.
“Based on our discussions with Western Australia we know their borders won’t be open to New South Wales and Victoria until early next year, so we’ve sadly had to cancel the flying we had planned on those routes in the lead-up to Christmas. We will maintain a minimum service for people with permits to travel, though, as we have throughout the pandemic.
“At this stage, Western Australia doesn’t intend to open to international travel until sometime next year, so we’ll unfortunately have to temporarily move our Perth-London service until at least April 2022.
“Instead of operating from Melbourne to Perth and then on to London as it usually does, this flight will operate from Melbourne to London via either Darwin or Singapore, depending on conversations we’re having with the Northern Territory in the coming weeks.
“We look forward to operating this flight via Perth again when circumstances allow.
“We’re in regular discussions with all the states and territories, and will continue to make adjustments, including increasing flying as soon as border settings allow.
“The pace of the vaccine rollout means we’re still on track for international flying to restart from 18 December onwards.
“People are clearly keen to travel. We saw a 175% spike in web searches in the week after we announced our plans and we’ve seen strong bookings for December and January for our flights to London, Los Angeles and Singapore in particular.
“The key factor in determining the ongoing demand level for international flying will be what the quarantine arrangements are for Australians when they return.”