People heading from Australia to Gallipoli for Anzac Day will largely be unaffected by the flight chaos caused by the volcanic ash cloud over Europe.
But Australians already in Europe planning to attend the dawn service at Anzac Cove probably won't be so lucky.
Istanbul Ataturk Airport is operating but several of Europe's major airports, including London Heathrow and Paris-Charles de Gaulle, remain shut.
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Hundreds head to Istanbul
Thirty-two passengers bound for Istanbul left Australia on Singapore Airlines flights on Sunday, and a further 335 are due to leave between Monday and Anzac Day, the airline's spokeswoman Susan Bredow said.
She said no delays were expected.
Veterans Affairs Minister Alan Griffin will leave Australia for Gallipoli later this week and isn't expecting delays.
Gallipoli trips run by Australian business Trans Turk Travel will proceed as planned, managing director Yekta Gokyildirim told AAP.
Difficulties from within Europe
About 200 people have already left Australia and 300 were scheduled to depart this week and shouldn't experience any problems, Mr Gokyildirim said.
However, around 230 people heading to Istanbul from elsewhere in Europe would find it very difficult to get to Gallipoli in time for Anzac Day, even if airports began operating, he said.
"Those who have missed their scheduled flights are going to be in a lot of trouble because of the backlog (of flights)," he said.
"They are not going to make it."
Travel via Dubai, Abu Dhabi
Tempo Holidays spokesman Ashley Jurberg said passengers leaving from Australia bound for Istanbul on Emirates and Etihad Airways flights would not be affected because they were travelling via Dubai and Abu Dhabi.
But those already in Europe may be delayed, he said.
"At this stage we're still hopeful that it (the volcanic ash cloud) won't have too much of an impact," Mr Jurberg told AAP.
"It will impact some people but if flights resume today or tomorrow European time then we should be alright."
Both Trans Turk Travel and Tempo Holidays have pledged to refund customers who miss tours due to the flight chaos.
Qantas extends cancellations
Qantas spokeswoman Olivia Wirth said Qantas flights between Australia and London would not operate on Monday or Tuesday.
"We remain hopeful that operations can once again commence at the end of the week," she said.
"We fly into Frankfurt and we codeshare into Paris, however, there are no operations that are flying into any of those European destinations at this this stage.
North Europe 'shut down'
"Effectively most ports in Northern Europe are shut down."
Iceland's Eyjafjoell volcano started erupting on Wednesday, sending ash drifting towards Europe and prompting flight restrictions that have affected nearly seven million passengers.
The enormous shroud of fine mineral dust particles now stretches from the Arctic Circle in the north to the French Mediterranean coast in the south, and from Spain into Russia.
The cloud is now heading toward Greece and into Russia.
