Qantas flights bound for Frankfurt and London will depart from Asian airports tonight following the reopening of European airspace.
Scheduled services between Australia and Europe via Asia will recommence tomorrow, Qantas Chief Executive Officer Alan Joyce said.
"We have been closely monitoring the evolving situation in Europe and liaising with European authorities about the opening of airspace across Europe," Mr Joyce said.
"We estimate it will take approximately two to three weeks to clear the current backlog."
A flight from London to Sydney via Singapore is scheduled to depart at 12.05pm local time, and a flight from London to Melbourne via Hong Kong will depart at 12.20pm local time.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Two flights from Singapore bound for London and one to Frankfurt are due to depart tonight.
There will also be one flight from Bangkok to London.
Early tomorrow, there will be a flight from Hong Kong to London.
From Thursday, Qantas will resume its normal scheduled services from Australia to Europe, with three flights leaving Sydney for London and two flights departing from Melbourne - one for London and one for Frankfurt.
Customers booked on those flights are confirmed for travel, Qantas said.
First flight to Europe leaves this afternoon
The first flight out of Sydney to northern Europe after the reopening of European airspace is due to leave on Wednesday afternoon.
Singapore Airlines flight SQ222 will leave Sydney Airport at 3.15pm for Singapore, where it is expected to arrive at 9.55pm Singapore time.
From there the flight will depart for London at 11.30pm Singapore time.
Heathrow reopened just before 10pm local time on Tuesday (0700 Wednesday AEST) after the UK's Civil Aviation Authority announced a gradual lifting of flight restrictions.
Dense volcanic ash had forced airports to close across the UK and Europe since last week, leaving thousands of passengers stranded.
