Ash cloud chaos: Recriminations over Europe flight ban
Geologist Pall Einarssonn: "The eruption has been declining"
There have been bitter recriminations over the almost week-long closure of large parts of European airspace because of volcanic ash from Iceland.
Airlines are seeking compensation from governments over the unprecedented shutdown, which they say cost them $1.7bn (£1.1bn).
But scientists have said regulators had few options beyond flight bans.
Iceland announced on Thursday that two of its four international airports will shut down because of the ash.
Keflavik and Reykjavik airports will be closed on Friday, Iceland's aviation authority said in a statement.
It is the first time the country's own airspace has been affected by the current eruption.
The air traffic agency Eurocontrol says it expects European flights to be back to "almost 100%" on Thursday.
A Eurocontrol spokeswoman said nearly all of the continent's 28,000 scheduled flights, including more than 300 flights on transatlantic routes, were expected to proceed. On Wednesday, about 80% of flights took place.
Airlines are clearing the backlog of uncompleted journeys, but thousands of travellers remain stranded around the world.
Six days after the eruption of the Eyjafjallajokull volcano in Iceland triggered the first airspace closures, the International Air Transport Association (IATA) criticised the bans.
"For an industry that lost $9.4bn last year and was forecast to lose a further $2.8bn in 2010, this crisis is devastating," IATA chief Giovanni Bisignani said.
"Airspace was being closed based on theoretical models, not on facts."
Mr Bisignani said the situation had been exacerbated by "poor decision-making" from governments and called on them to compensate airlines, something which the European Commission has said it is considering.
"I am the first one to say that this industry does not want or need bailouts. But this crisis is not the result of running our business badly," he added.
Some airlines are also demanding changes to EU passenger compensation rules, which require them to provide accommodation for those prevented from flying.
Michael O'Leary, the chief executive of the low-cost carrier Ryanair, had said it was "absurd" that his firm had to spend thousands of euros on someone whose ticket might have cost only a few euros.
I think if they'd sent up planes immediately to see whether the ash was actually too dangerous... we would have been back flying a lot sooner
Sir Richard Branson Chairman, Virgin Group
Ryanair had earlier said reimbursement would be limited to the original air fare paid by each passenger.
However it later issued a statement saying it would comply with the EU rules and would refund passengers for "reasonably-receipted expenses".
Virgin Group chairman Sir Richard Branson meanwhile told the BBC that he believed governments would be unlikely to impose a blanket ban again.
"I think if they'd sent up planes immediately to see whether the ash was actually too dangerous to fly through or to look for corridors where it wasn't very thick, I think that we would have been back flying a lot sooner," he said.
The bans were imposed because volcanic ash - a mixture of glass, sand and rock particles - can seriously damage jet engines.
The European decision to partially reopen airspace did not come until the fifth day of the crisis, when transport ministers met by teleconference.
In the UK, training on Royal Air Force Typhoon jets was suspended on Thursday after ash deposits were found in one aircraft's engines.
Camping at New York's JFK airport
An RAF spokesman said Typhoons were "very high performance jets" and staff were "just being extra cautious".
Britain's Civil Aviation Authority said no conclusion should be drawn on the airworthiness of civilian aircraft, which have shown no sign of ash damage.
Henri Gaudru, the president of the European Volcanological Society, defended the earlier the flight bans.
"This was not an overreaction. We... do not know enough about these clouds and what can happen to planes flying into them," he told a news conference in Geneva.
Despite Thursday's near-normal traffic, a number of fresh disruptions have been reported.
In southern Sweden Gothenburg and Malmo airports closed on Wednesday, when part of the volcanic ash cloud took an unexpected turn north.
Flight bans imposed on Norway's second and fourth largest airports were later lifted, clearing the whole of Norwegian airspace. Air restrictions also continue to apply to northern Scotland and parts of Finland.
A fresh volcanic ash alert led Australian airline Qantas to cancel one flight out of London and delay another for 11 hours until early on Thursday, infuriating passengers.
In Iceland, the Eyjafjallajokull volcano continues to erupt, but it is no longer spewing out ash into the atmosphere.
"There is much, much, less ash production and the plume is low," Gudrun Nina Petersen of the Icelandic Met Office said.
Are you due to fly today? Have you made it to your destination? Or are you still stranded? Send us your comments.
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