By Ralph Gowling
LONDON (Reuters) - A sprawling cloud of volcanic ash paralysed air travel across much of Europe for a fourth day Sunday, but test flights with empty airliners showed no sign of damage and offered some hope of respite.
British transport minister Andrew Adonis said European Union transport ministers would examine the results of the test flights Monday and consider whether air space might be reopened despite ash from an Icelandic volcano.
Volcanic ash is abrasive and can strip off vital aerodynamic surfaces and paralyse an aircraft engine. Aircraft avionics and electronics, as well as windshields, can also be damaged.
British Airways and Irish Aer Lingus highlighted uncertainty over any reopening of air space in the immediate future by cancelling all of their flights for Monday.
Dutch airline KLM said inspection of an airliner after a test flight showed no damage to engines or evidence of dangerous ash concentrations. Germany's Lufthansa also reported problem-free test flights, while Italian and French carriers announced they would fly empty airliners Sunday.
The Association of Dutch Pilots said it believed, along with sister organizations, that a partial resumption of flights was possible despite the continuing eruption spewing black ash high over Europe.
"The concentration of ash particles in the atmosphere is in all likelihood so little it poses no threat to air transport," said association chairman Evert van Zwol.
TORTUOUS ROUTE
The imaginative traveller sometimes found a way, weaving at the edges of the sprawling cloud. Reuters correspondent Mark Meadows flew over two days from St Petersburg to Rome, via Istanbul and Athens, then homewards by train to Milan.
"It's possible to fly around the 'cloud', and the fact I could still find seats suggests not everyone has seen that possibility," he said.
The Spanish EU presidency called a video conference of EU transport ministers Monday.
"We can examine the results of the test flights and look and see whether there is any updating of the regulatory structure which might make it possible for flights to take place despite the presence of the ash cloud," Britain's Adonis told BBC television.
Through Sunday, a clampdown held across much of Europe, posing a growing problem for businesses -- especially airlines, estimated to be losing $200 million (130.22 million pounds) a day -- and for thousands of travellers stranded worldwide.
The European aviation agency Eurocontrol said only 4,000 flights were expected in European airspace Sunday, compared with 24,000 normally. It said a total of 63,000 flights had been cancelled in European airspace since Thursday.
Many countries, including Austria, Britain, France, Denmark and Sweden, closed their airspace into Monday. Russian airports remained open, routing planes to North America over the North Pole to avoid the cloud. Weather experts said wind patterns meant it was not likely to move far until later in the week.
The plume was expected to become more concentrated Tuesday into Wednesday, posing a greater threat to air travel, but narrowing to affect a smaller area. A shift in jet stream winds from Thursday could purge the plume out of most of Europe.
"It's like a spray can of ash coming from Iceland," U.S.- based forecaster AccuWeather said. "As with a spray can, the plume of ash is not uniform. It becomes deformed and spreads out in different directions the farther way from the source it gets."
For some businesses dependent on the speed of air freight, the impact has been immediate.
Kenya's flower exporters said they were already losing up to $2 million a day because they had not been able to airlift their blooms. Kenya accounts for about a third of flower imports into the European Union.
DANGEROUS ASH
KLM, acting on a European Union request, flew a Boeing 737-800 without passengers at the regular altitude of 10 km (6 miles) and up to the 13 km maximum Saturday. Germany's Lufthansa said it flew 10 empty planes to Frankfurt from Munich at altitudes of up to 8 km.
"We hung up filters in the engines to filter the air. We checked whether there was ash in them and all looked good," said a KLM spokeswoman. "We've also checked whether there was deposit on the plane, such as the wings. Yesterday's plane was all well."
German airline Air Berlin was quoted as expressing irritation at the way the shutdown was decided.
"We are amazed that the results of the test flights done by Lufthansa and Air Berlin have not had any bearing on the decision-making of the air safety authorities," Chief Executive Joachim Hunold told the mass circulation Bild am Sonntag paper.
Britain's Civil Aviation Authority questioned the worth of airliner test flights. "You can tell when you land the aircraft whether you have done any damage to it. Whether that is a scientific test flight or not, would be for someone else to say," a spokesman said.
The disruption is the worst since the September 11 attacks on New York and Washington in 2001, when U.S. airspace was closed for three days and European airlines were forced to halt all trans-atlantic services.
U.S. President Barack Obama, German Chancellor Angela Merkel and others cancelled trips to Poland for the funeral of Polish President Lech Kaczynski.
For travellers, businesses and financial markets the biggest problem remains the sheer unpredictability of the situation.
German flight controllers appeared to have seized on an 'opening' Sunday when, for a few hours, they cleared flights from several cities.
ECONOMIC HAZARDS
Economists say they stand by their models or predictions for European growth, hoping normal service can resume this week.
But if European airspace were closed for months, one economist estimated lost travel and tourism revenue alone could knock 1-2 percentage points off regional growth. European growth had been predicted at 1-1.5 percent for 2010.
"That would mean a lot of European countries wouldn't get any growth this year," said Vanessa Rossi, senior economic fellow at Chatham House. "It would literally stifle the recovery. But the problem is it is incredibly hard to predict what will happen. Even the geologists can't tell us."
Chris Weafer, Chief Strategist at Russian bank Uralsib, currently stranded in Abu Dhabi en route to London from Singapore, said the only market fundamental investors were following was "the wind direction across Europe."
"The volcano has the potential to undermine Europe's fragile recovery and that would have global consequences. So much global trade and commerce is airborne these days that any extended disruption will have immediate impact on investment and growth."
Disruption spread to Asia, where dozens of Europe-bound flights were cancelled and hotels from Beijing to Singapore strained to accommodate stranded passengers.
More than four in five flights by U.S. airlines to and from Europe were cancelled Saturday. Shipping company FedEx Corp said more than 100 FedEx Express flights headed to Europe were rerouted, diverted or cancelled within the past 72 hours.
The volcano began erupting Wednesday for the second time in a month from below the Eyjafjallajokull glacier, hurling a plume of ash 6 to 11 km (3.7 to 6.9 miles) into the atmosphere.
(Reporting by London, Geneva, Dublin, Paris, Amsterdam, Brussels, Reykjavik, Washington, Frankfurt and Berlin newsrooms; Writing by Ralph Gowling and Ralph Boulton; editing by Mark Trevelyan)
