(AP) -- Britain sent Royal Navy warships on Monday to rescue those stranded across the Channel by the volcanic ash cloud, and the aviation industry blasted European transport officials, claiming there was "no coordination and no leadership" in the crisis that shut down most European airports for a fifth day.
Eurocontrol, the air traffic agency in Brussels, said less than one-third of flights in Europe were taking off Monday - between 8,000 and 9,000 of the continent's 28,000 scheduled flights.
Some smaller airports reopened Monday but authorities in Britain, France, Germany, and the Netherlands - home to four of Europe's five largest airports - said their air space was still closed. Britain said it was keeping flight restrictions on through early Tuesday while Italy briefly lifted restrictions in the north then quickly closed down again after conditions worsened Monday.
Prime Minister Gordon Brown said the aircraft carrier HMS Ark Royal and assault ship HMS Ocean would be sent across the English Channel. A third ship is being spent to Spain to pick up soldiers trying to get back to Britain after a tour of duty in Afghanistan.
"I expect Ocean to be in the Channel today. I expect the Ark Royal to moving towards the Channel later," Brown said after a meeting of the government's emergency committee, known as COBRA.
He said Britain was speaking with Spanish authorities to see whether Britons stranded overseas could be flown there and then taken home by boat or bus.
Brown said the ash cloud had created "the biggest challenge to our aviation transport network for many years."
The International Air Transport Association says the airport lockdowns are costing the aviation industry at least $200 million a day. Millions of travelers have been stuck since the volcano under Iceland's Eyjafjallajokull glacier begun erupting Wednesday for the second time in a month.
Meeting in Paris, the IATA expressed its "dissatisfaction with how governments have managed it, with no risk assessment, no consultation, no coordination, and no leadership" and called for greater urgency in reopening Europe's skies.
Several major airlines safely tested the skies with weekend flights that did not carry passengers. The announcement of successful test flights prompted some airline officials to wonder whether authorities had overreacted to concerns that the microscopic particles of volcanic ash could cause jet engines to fail.
Transport ministers from Britain, Germany, France and Spain were meeting Monday via videoconference and later joined by all 27 EU transport ministers, said French Transport Minister Dominique Bussereau.
"We will try to outline corridors, if we can, based on the evolution of the cloud, to allow the reopening of as large a number of flight paths as possible, as quickly as possible and in good security conditions," Bussereau said.
Eurocontrol said Monday that southern Europe, including Portugal, Spain, parts of Italy and France, the Balkans, Bulgaria, Greece and Turkey, and parts of northern Europe were currently open for flights.
EU Transport Commissioner Siim Kallas told reporters in Brussels that "it is clear that this is not sustainable. We cannot just wait until this ash cloud dissipates."
"Now it is necessary to adopt a European approach" instead of a patchwork of national closures and openings, said Diego Lopez Garrido, state secretary for EU affairs for Spain, which holds the rotating EU presidency.
Tensions boiled over at Incheon International Airport in South Korea, where 30 frustrated passengers blocked a Korean Air ticketing counter and demanded officials arrange travel to anywhere in Europe after hearing about the test flights.
They held up a makeshift sign saying, "We want to come back home," each word written on a separate piece of paper and held by an individual traveler.
"We need a flight, we need a time," Thierry Loison, who has been stuck at the airport since Friday on the way back to France, told Korean Air officials. "We were like animals this morning."
Passengers complained about having to sleep on the airport floor due to a lack of hotel rooms and said they were only receiving a voucher for one meal a day at McDonald's. Some were running out of money.
"We are on the floor," Andrew Turner, a graduate student en route to London after a holiday in Sydney, told Korean Air officials, referring to sleeping accommodations. "We have one meal a day ... at the moment a lot of people are not eating."
KLM Royal Dutch Airlines said it had flown four planes Sunday through what it described as a gap in the layer of microscopic dust over Holland and Germany. Air France, Lufthansa and Austrian Airlines also sent up test flights, although most traveled below the altitudes where the ash has been heavily concentrated.
"There is currently no consensus as to what consists an acceptable level of ash in the atmosphere," said Daniel Hoeltgen, a spokesman for the European Aviation Safety Agency. "This is what we are concerned about and this is what we want to bring about so that we can start operating aircraft again in Europe."
KLM said its received permission from Dutch and European aviation authorities for planes of various types to fly the 115-mile (185-km) flight from Duesseldorf in western Germany to Amsterdam's Schiphol Airport at an unspecified normal altitude above 10,000 feet (3,000 meters). They did not encounter the thick though invisible cloud of ash, whose main band has floated from 20,000 to 32,000 feet, the height of most commercial flight paths.
"With the weather we are encountering now - clear blue skies and obviously no dense ash cloud to be seen, in our opinion there is absolutely no reason to worry about resuming flights," said Steven Verhagen, vice president of the Dutch Airline Pilots Association and a Boeing 737 pilot for KLM.
Meteorologists warned, however, that the situation above Europe remained unstable and constantly changing with the varying winds - and the unpredictability was compounded by the continuing eruptions.
Air France said its first test flight Sunday, from Charles de Gaulle airport to Toulouse in southern France, "took place under normal conditions." It did not say how high the planes had flown.
Germany's Lufthansa flew 10 empty long-haul planes Saturday to Frankfurt from Munich at low altitude, between 3,000 and 8,000 meters (9800 and 26000 feet), under so-called visual flight rules, in which pilots don't have to rely on their instruments, said spokesman Wolfgang Weber.
"Not the slightest scratch was found on any of the 10 planes," he said.
Air Berlin, Germany's second-biggest airline, said it had transferred two planes from Munich to Duesseldorf and another from Nuremberg to Hamburg without problems on Saturday. They flew at 9,840 feet (3,000 meters).
A technical inspection of the aircraft after landing "did not reveal any adverse effects," the company said.
Air Berlin Chief Executive Joachim Hunold declared himself "amazed" that the results of the German airlines' flights "did not have any influence whatsoever on the decisions taken by the aviation safety authorities."
Ash and grit from volcanic eruptions can sabotage a plane in various ways: the abrasive ash can sandblast a jet's windshield, block fuel nozzles, contaminate the oil system and electronics and plug the tubes that sense airspeed. But the most immediate danger is to the engines. Melted ash can then congeal on the blades and block the normal flow of air, causing engines to lose thrust or shut down.
Scientists say that because the volcano is situated below a glacial ice cap, magma is being cooled quickly, causing explosions and plumes of grit that can be catastrophic to plane engines, depending on prevailing winds.
"Normally, a volcano spews out ash to begin with and then it changes into lava, but here it continues to spew out ash, because of the glacier," said Reynir Bodvarsson, director of Swedish National Seismic Network. "It is very special."
Bodvarsson said the relative weakness of the eruption in Iceland also means the ash remains relatively close to the earth, while a stronger eruption would have catapulted the ash outside of the atmosphere.
In 1989, a KLM Boeing 747 that flew through a volcanic ash cloud above Alaska temporarily lost all four motors. The motors restarted at a lower altitude and the plane eventually landed safely.
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