The Icelandic volcano Grímsvötn has stopped spewing ash but its plume caused severe flight disruptions in Germany on Wednesday with tens of thousands of passengers affected by the temporary closure of the airports of Berlin, Hamburg and Bremen.
The flight ban issued for Hamburg and Bremen was lifted at midday after six hours. It remained in place for Berlin's two airports, Tegel and Schönefeld, which were closed at 11:00 a.m. CET and are due to reopen at 2 p.m., the German air traffic control authority said.
Eurocontrol, Europe's air traffic control body, said the cloud may also affect parts of Poland. There were no restrictions on flights anywhere else in Europe.
The ash cloud had led to some 500 flight cancellations in northern Europe on Tuesday, most of them affecting flights to and from Scotland and Northern Ireland. Ten flights were cancelled in Sweden on Tuesday night, with Norway and Denmark also affected.
Germany's national carrier Lufthansa said on Wednesday it expected to cancel some 150 flights. At the country's main airport in Frankfurt, some 20 flights to and from the affected airports were grounded. Passengers were issued train tickets instead.
European officials say the flight disruption from Grímsvötn is unlikely to become as severe as the chaos caused by Iceland's Eyjafjallajökull volcano in April 2010 when thousands of flights were cancelled, large parts of European airspace were closed for days at a time and mass disruptions continued for nearly a month.
Transport Minister Confident Ash Will Clear Soon
German Transport Minister Peter Ramsauer said after consultations with experts from the German Weather Service and the air traffic control authority that he expected the flight ban to be lifted on Wednesday afternoon.
He said there were no new ash concentrations heading towards Germany and that the skies should be clear once the present cloud had passed. The minister said in a TV interview there was a "solid legal basis" for the flight ban, which has been criticized as too draconian by airlines.
Other European countries have adopted the German guideline of banning flights when the concentration of ash exceeds two milligrams per cubic meter. "Safety comes first," Ramsauer told the public ARD TV network on Wednesday morning.
Researchers in Germany said the ash concentration appeared to be far lower than a year ago. The Forschungszentrum Jülich research center said it had measured the density of the ash cloud by directing laser beams into the air above northern Germany. "The ash concentration appears to very low overall," the center said in a statement, adding that more detailed results would be available later.
The only danger now comes from the old ash that is still in the air, said a spokesman for Iceland's crisis management group. Officials said the volcano appeared to have stopped emitting ash in the early hours of Wednesday morning.
On Tuesday, European budget airline Ryanair questioned the decision by Irish authorities to cancel its flights to and from Edinburgh, Glasgow and Aberdeen. The airline said in a statement: "Ryanair strongly objects to this decision and believes that there is no basis for these flight cancellations and is meeting with the Irish Aviation Authority this morning to have this restriction on Ryanair flights removed as a matter of urgency."
Ryanair said it had operated a one-hour "verification flight" in Scottish airspace on Tuesday morning, taking off from Glasgow, flying to Inverness, on to Aberdeen and down to Edinburgh. "There was no visible volcanic ash cloud or any other presence of volcanic ash and the post flight inspection revealed no evidence of volcanic ash on the airframe, wings or engines," said Ryanair.
The International Air Transport Association (IATA) criticized the British air traffic control authority, saying it was "astonishing and unacceptable" that the British government wasn't conducting its own tests on the cloud's density.
The British National Air Traffic Service (NATS), which controls traffic across Britain's airspace, said it was relying on forecasts by the official meteorological services.
British Airways said it had sent an Airbus A320 jet on a test flight to Scotland on Tuesday evening to ascertain the risks posed to the aircraft by the ash in the air.