Flights between Victoria and NSW will now begin on November 5, earlier than the previous date of December 1. The change is based on Victoria's reopening plan.

However, as previously flagged, Qantas will temporarily reroute its flagship Perth-London service until at least April 2022 due to border restrictions with WA.

International flights are on track to restart from December 18, when Australia is expected to have reached National Cabinet's "Phase C" vaccination threshold of 80 per cent.

The carriers have also delayed the restart of domestic flights between Western Australia and Victoria or New South Wales by two months to February 1, 2022, based on border assumptions.

Qantas is in talks with the Northern Territory Government and Darwin Airport to assess operating the direct London flight from Darwin during this time.

Darwin has been used as a hub for its repatriation flights to various destinations across Europe, Asia and the Middle East over the past 12 months.

Qantas says discussions for what would be a daily Melbourne-Darwin-London service will focus on the logistics of domestic and international transit.

If this service can't operate through Darwin, it will instead fly Melbourne-Singapore-London until at least April 2022.

A decision on the exact routing is likely to be made within the next two weeks.

Qantas CEO Alan Joyce welcomed the restart of flights due to the take up of the vaccine.

"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," Mr Joyce said.

"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.

"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, WA 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 NT in the coming weeks."

Qantas says that should the state or federal roadmaps change, and flights are cancelled, customers may be eligible for a refund, credit voucher or to change the date of their travel.

Regional flights within NSW will also significantly increase from October 25, taking it to around 40 per cent of pre-COVID levels.

However, fully vaccinated NSW residents must now wait until that 80 per cent double-dose mark, rather than the previously touted 70 per cent milestone, to travel freely around the state.