European skies were a virtual no-fly zone for a fourth day on Sunday, with volcanic ash drifting from Iceland reaching as far as Russia, stranding tens of thousands of people as over 17,000 flights were cancelled.
About 30 countries have now closed or restricted their airspace, with the volcanic ash creating chaos over the vast swathe of the European continent, right from the Arctic circle in the north to the French Mediterranean coast in the south and from Spain into Russia.
Over 40,000 flights have been cancelled since the volcano erupted throwing ash and fine particles across the European skies on safety concerns. The grounding of major airliners was costing the industry at least $ 200 million a day, according to International Air Transport Association.
The flight cancellations also affected attendance of world leaders at the funeral of late Polish President Kaczynski. US President Barack Obama was unable to fly to Krakow city for the funeral. Prince Charles and British foreign Secretary David Miliband also cancelled their journey to Poland to attend the last rites of Kaczynski, who died in a plane crash in Russia last week.
In Britain, flight restrictions were extended until at least 0100 BST (530 IST) on Monday and forecasters say the ash cloud could remain over the UK for many more days.
In a bid to ease the travel chaos, Netherlands and a few other countries have started test flights to see if jets could safely fly, either below or over the ash clouds.
Dutch airline KLM and German airline Lufthansa carried out test flights in their countries' airspace to see if it is safe for planes to fly. KLM said its aircraft had been able to fly its normal operating altitude of 13km over Dutch skies and no problems had been reported.
The plane's engines were being inspected for possible damage, with a view to getting permission from the aviation authorities to start up operations again. German carrier Lufthansa said it flew 10 planes from Frankfurt to Munich at lower altitudes.
"We have found nothing unusual, neither during the flight, nor during the first inspection on the ground," KLM chief executive Peter Hartman, who took part in his airline's test, said in a statement.
British Airways cancelled all flights in and out of London for the whole day today. Germany and most Scandinavian and central European countries kept the flight ban in place, extending the biggest airspace shutdown since World War II.
With the blanket spreading, Italy and Spain said they would not allow flights into the northern parts of their countries. The cloud is now heading toward Greece and into Russia.
Meanwhile, the IATA warned airlines would lose at least $ 200 million per day in revenues during the disruption. Planes were first grounded midday on Thursday amid fears that particles in the ash cloud generated by the volcanic eruption could cause engines to shut down.
National Air Traffic Control Services said the ash cloud showed "continued and extensive" cover of the UK.
Prof Brian Golding, head of forecasting research at the Met Office, said it looked like the ash would remain over the UK "for several days".
"We need a change of wind direction that stays changed for several days and there is no sign of that in the immediate future," he said.
A plume of ash 8.5 km high was visible in Iceland on Saturday. In Russia, where the volcanic cloud is now headed, 500 flights were cancelled due to the ash and the closure of European air space with 32,000 air passengers stranded in Russian airports by noon today.
According to ITAR-TASS almost 500 flights were cancelled in three Moscow international airports and Kaliningrad, Rostov-on-Don, Samara, Yekaterinburg, Novosibirsk and Tyumen by noon. Prime Minister Vladimir Putin today summoned an emergency meeting of the cabinet to take the stock of the situation.
He ordered the Foreign Ministry to send consular officials to the airports to extend visas of the stranded foreigners and said the government could consider compensation of the financial losses to the Russian airlines. Russian President Dmitry Medvedev, however, left for Krakow by air, to attend the funeral of Kaczynski. Briefing Putin, Transport Minister Igor Levitin said the cloud of volcanic ash would reach Ural Mountains -- the geographical boder of Europe and Asia in 3-4 days, however, domestic and Asia bound flights are not affected.
Levitin said 12,000 Russia bound passengers are stranded in various European airports. Asia-Pacific airlines cancelled dozens of European flights for a third day today and warned that chaos caused by a freak volcanic ash cloud could last for a week.
Australia's Qantas Airways grounded all flights till Tuesday afternoon. At Singapore's Changi airport, 34 flights were cancelled today, taking the total to nearly 120.
In South Korea, Korean Air and Asian Airlines axed another 28 services between them. China's top operators Air China and China Southern Airlines also cancelled most flights to Europe, while about 40 flights were affected at the Hong Kong's airport.
Image: A cloud of black ash looms over a farm at Drangshlid 2 in Eyjafjoll, Iceland, on Sunday