A huge cloud of ash from a volcano in Iceland turned the skies of northern Europe into a no-fly zone today, leaving hundreds of thousands of passengers stranded.
The European aviation control agency Eurocontrol said the disruption, the biggest seen in the region, could last another two days and a leading volcano expert said the ash could present intermittent problems to air traffic for six months if the eruption continued.
Eurocontrol said the air space closures could result in a 20 to 25 per cent reduction in Europe commercial air traffic movement. Even if the disruption is short lived, the financial impact on airlines is likely to be significant.
The volcano began erupting yesterday for the second time in a month from below the Eyjafjallajokull glacier. It hurled a plume of ash up to 11km into the atmosphere, and this spread south east overnight.
Volcanic ash contains tiny particles of glass and pulverised rock which can damage engines and airframes and an Icelandic volcanologist said today the eruption was growing more intense.
Most of Britain's airspace will remain closed to all but emergency flights until at least noon tomorrow, aviation officials said this evening.
Some flights from Northern Ireland and the Western Isles of Scotland to and from Glasgow, Edinburgh and Prestwick may be allowed to fly.
The UK's air traffic control body said it was reviewing the situation and would give an update at 1.30am tonight that will cover the period to 5pm tomorrow.
It was the first time "within living memory" that a natural disaster had caused such a halt, a spokeswoman for Britain's National Air Traffic Service (NATS) said. Even after the September 11th, 2001 attacks on US cities, Britain did not close its air space, she said.
Northern French airports were due to be shut in stages this evening, with Paris airports to shut tonight at the latest. Brussels, Amsterdam and Geneva airports said they had cancelled a large number of flights and Eurocontrol spokesman Brian Flynn said this afternoon the problem could persist for a further 48 hours.
Sweden said it would close its airspace tonight. All air traffic in and out of Norway's main Oslo Airport was cancelled while flights from Denmark's Copenhagen airport were also severely disrupted.
Finland's airport manager Finavia said central and northern Finland's air space would be closed until noon tomorrow, and Finnair said it had cancelled nearly 50 domestic and international flights.
Norway's King Harald V and Queen Sonja - who had planned to fly today to Copenhagen for the Danish queen's 70th birthday - were looking to take a "car, boat or train." A canceled transatlantic flight left Norway's prime minister Jens Stoltenberg grounded in New York.
A spokeswoman for the German air traffic body said there were no immediate plans to shut German airspace. Rail company Eurostar said it had received a big boost due to the disruption to air travel, with hundreds of enquiries from stranded passengers trying to enter or leave Britain.
Airline staff at Stansted airport, north-east of London, told customers it could be closed until Sunday, said stranded passenger Andy Evans. "People just don't know what to do," he said. "There are hundreds of people in the queues at the sales desks."
A spokesman at Heathrow, Europe's busiest airport, said 840 out of 1,250 flights today were affected, disrupting about 180,000 passengers. More than 120,000 other passengers were affected at Gatwick, Stansted and Glasgow airports.
"There is a big financial impact on the airlines," said John Strickland, director of air transport consults JLS consulting. "We are now looking at at least a day's business wiped out for the airline business ... even if things were meteorologically fine to fly tomorrow by that time the airlines will have all their aircraft and crew out of position so they have no choice but to cancel further flights."
The US Geological Survey said about 100 encounters of aircraft with volcanic ash were documented from 1983 to 2000; in some cases engines shut down briefly after sucking in volcanic debris, but there have been no fatal incidents.
In 1989, a KLM Royal Dutch Airlines Boeing 747 flew into an ash cloud from Alaska's Redoubt volcano and lost all power, dropping from 7,500 metres to 3,600 before the crew could get the engines restarted. The plane landed safely.
In 1982 a British Airways Boeing 747 lost power in all its engines when it flew into an ash cloud over Indonesia, gliding towards the ground before it was able to restart its engines. The incident prompted the aviation industry to rethink the way it prepared for ash clouds, resulting in international contingency plans activated today.
Scientists said the ash did not pose any health threat because it is at such a high altitude.
Bill McGuire, professor at the Aon Benfield UCL Hazard Research Centre, said if the volcano continued erupting for more than 12 months, as it did the last time, periodic disruptions to air traffic could continue.
"The problem is volcanoes are very unpredictable and in this case we have only one eruption to go on," he said. "And a lot depends on the wind. I would expect this shutdown to last a couple of days. But if the eruption continues - and continues to produce ash - we could see repeated disruption over six months or so."
Brian Flynn, deputy head of operations at Eurocontrol, said the disruption was already unprecedented: "The extent is greater than we've ever seen before in the EU."
"The meteorological situation is such that the volcanic ash is progressing very slowly eastwards but there is not a lot of wind... so it is very slow and very dense."
Russian prime minister Vladimir Putin was forced to cancel a trip to Russia's Arctic town of Murmansk today. "The cloud has covered the entire region. Flights are not allowed," said Putin's spokesman Dmitry Peskov.
The eruption has grown more intense, University of Iceland volcanologist Armannn Hoskuldsson said.
To the east of the volcano, thousands of hectares of land were covered by a thick layer of ash, while a cloud was blotting out the sun in some areas along the southern coast of Iceland, local media reported.
Volcanic ash is formed from explosive eruptions. Particles as hard as a knife blade range in size from as small as 0.001mm to 2mm, the Geological Survey said. Ash can melt in the heat of an aircraft engine and then solidify again, disrupting the mechanics.
Agencies