British air traffic controllers warned a new ash cloud was headed for major air routes, prompting British Airways to cancel its short-haul flights, while several countries either closed airports anew or curtailed use of their airspace.
Poland, which had reopened four airports on Monday, closed them again on Tuesday, as well as shutting the northern part of its airspace to transit flights, citing the ash cloud.
Hungary closed part of its western airspace below 6,000 m (20,000) ft due to higher amounts of volcanic ash, its air traffic authority said, and Ireland said the renewed eruption of the Icelandic volcano on Monday, and prevailing weather conditions, forced it to extend its airspace closure.
"The density of volcanic ash over Irish airspace is such that restrictions will have to continue until 1300 hours (8 a.m. ET) today at least," the Irish Aviation Authority said in a statement.
Britain's biggest airports remained closed, and even where flights resumed, at the Edinburgh and Glasgow airports in Scotland, the service was limited.
"It's really just Scottish domestic flights, maybe a couple of international ones, there's one going to Iceland – yes, it's ironic, isn't it?" said Glasgow airport information officer Steven Boyle.
Details remained sketchy of how the authorities would split European airspace into areas where aircraft could fly or not and other countries were adopting a more cautious approach.
"The volcano eruption in Iceland has strengthened and a new ash cloud is spreading south and east toward the UK," NATS, Britain's National Air Traffic Services, said in an overnight statement.
"This demonstrates the dynamic and rapidly changing conditions in which we are working."
EU Transport Commissioner Siim Kallas said on Monday, after a ministerial video conference, that more flights would leave on Monday, easing days of disruption for millions of passengers. A handful of flights left Amsterdam and Frankfurt late on Monday.
The deal offered hope to frustrated airlines losing $250 million a day from the shutdown and seeing their shares tumble. The global freight supply chain is also beginning to sag.
"I'm so happy," said one man with tears in his eyes as he ran for his flight from Amsterdam's Schiphol Airport on Monday, one of three bound for New York, Shanghai and Dubai with almost 800 passengers on board.
Dutch Transport Minister Camiel Eurlings promised that the Netherlands was "taking a lead" in getting Europe moving, but said its airspace could be closed again if ash levels rose.
Neighboring Germany will mostly maintain its no-fly zone until 8 a.m. ET.
Some areas open to flights
Under the deal, which Kallas said would take effect from 2 a.m. ET, the area immediately around the volcano will remain closed.
But flights may be permitted in a wider zone with a lower concentration of ash, subject to local assessments and scientific advice, the European aviation control agency Eurocontrol said.
Airlines had declared numerous test flights problem-free over the past days, but experts disagree over how to measure the ash and who should decide it is safe to fly. A British Airways jet lost power in all four engines after flying through an ash cloud above the Indian Ocean in 1982.
France said it was reopening some airports to create air corridors to Paris. Italian airspace will open from 2 a.m. ET.
Eurocontrol said it expected up to 9,000 flights to have operated in Europe on Monday, a third of normal volume.
"The scale of the economic impact (on aviation) is now greater than 9/11, when US airspace was closed for three days," International Air Transport Association (IATA) head Giovanni Bisignani said.
"We must move away from this blanket closure and find ways to flexibly open air space, step by step."
Industry losses worldwide for passenger airlines and cargo companies could reach as much as $3 billion from the cloud, Helane Becker, an analyst with Jesup & Lamont Securities, told Reuters Insider on Monday. For US airlines, she estimated the impact at $400 million to $600 million.
Firms dependent on fast air freight were feeling the strain.
Kenya's flower exporters, which account for a third of EU imports, said they were losing up to $2 million a day.
Disruption extended far into Asia.
South Korea's Incheon International Airport, the world's fourth-busiest cargo handler in 2008, suffered 3,216 tonnes of lost shipments to Europe from April 16-19, the country's customs agency says.
Twenty inbound and 25 outbound cargo flights had been canceled. Among those suffering were computer chip and electronics suppliers such as Samsung Electronics and Hynix Semiconductor.
Japan Airlines said it had canceled 55 European flights, affecting 14,277 passengers. All Nippon Airways (ANA) has canceled 33 flights, affecting about 8,500.
Showers, hamburger, bus tours
Tokyo's Narita airport offered stranded passengers free showers, hamburgers, access to rest areas and bus tours of the city. About 140 passengers spent last night at the airport.
The China Daily said the bar on flights to Europe remained in effect and quoted a civil aviation spokeswoman as saying that "the situation might last for a few more days."
It also reported European executives might be unable to attend a series of conventions and exhibitions, including the Beijing auto show that opens with a media day on Friday.
"I don't know how many of the European auto giants will finally show up on the media day," the paper quoted Zhang Hengjie, a manager at the exhibition center, as saying.
In Singapore, a hub for travel throughout Asia, France's ambassador urged French residents of the island state to take in compatriots stranded at the airport.
Millions of people have had travel disrupted or been stranded and forced to make long, expensive attempts to reach home by road, rail and sea, as well as missing days at work and school at the end of the busy Easter holiday season.
British businessman Chris Thomas, trying to get home from Los Angeles since Thursday, flew to Mexico City and then aimed to fly to Madrid and spend $2,000 to rent a car for the 14-hour drive to Paris. He was booked on the Eurostar Channel tunnel train to London, and then planned to drive four hours to Wales.
"It's all a bit crazy but you have to err on the side of caution," Thomas said. "Nobody wants to be on the first plane to go down in a volcanic cloud."
In sport, soccer's European Cup holders Barcelona set off on a two-day road trip of nearly 1,000 km (620 miles) on Sunday to play Inter Milan in a Champions League semi-final on Tuesday.
Businesses have had to find alternative ways of operating. Communications provider Cisco Systems said companies were turning to videoconferencing to connect executives.
Britain was deploying three navy ships, including an aircraft carrier, to bring its citizens home from continental Europe. The British travel agents' association ABTA estimated 150,000 Britons were stranded abroad. Washington said it was trying to help 40,000 Americans stuck in Britain.