KENT, England — Increasing amounts of ash from Iceland’s Grimsvotn volcano have prompted questions about what European air traffic regulators learned from last year’s Eyjafjallajokull eruption, which stranded 10 million travelers when authorities closed airspace for more than eight days.
“Last year, the airport closures spun out of control,” said Frank Furedi, a sociology professor at the University of Kent who studies risk awareness. “What [authorities] have now realized is that they have far more leeway to take a calculated risk.”
Volcanic ash is drifting over Scotland and heading farther south. More than 500 flights have been canceled in Britain.
Scotland and Northern Ireland have closed their airspace, and airlines such as British Airways, KLM and Aer Lingus have grounded their planes. Fears of more closures are mounting.
Ash reached Norway on Tuesday, and Hamburg in northern Germany is bracing for closures.
Other countries are monitoring the situation. Ash isn’t expected to reach France before Friday, and authorities don’t plan to ground flights, the French environment minister said.
“It comes down to wind direction,” said Richard Taylor, a spokesman for Britain’s Civil Aviation Authority. “It’s just unlucky that wind patterns from the northwest carrying ash over northern Europe have coincided with the major eruptions.”
Andrew Doyle, head of content for aviation industry website FlightGlobal.com, said the industry was unprepared for the ash cloud last year because Europe had experienced few volcanic eruptions in recent history.
“In the past, it was feasible to say, ’We will never fly through any concentration of ash,’ ” he said. “During the past 12 months, the industry has been working hard with meteorologists to develop procedures to allow planes to fly around and through low concentrations of ash.”
Nevertheless, memories abound of last year’s flight disruptions, which cost the airline industry billions of dollars.
Even Air Force One is concerned about disruption: President Obama cut short his visit to Ireland on Monday and left for Britain a night early rather than risk being stranded because of ash.
Mr. Obama is due to arrive in Poland on a state visit Friday, having missed the funeral of Polish President Lech Kaczynski last year because of Eyjafjallajokull’s ash cloud. No further changes to the president’s travel plans have been announced.
Grimsvotn, which began erupting Saturday, is thought to be significantly more powerful than Eyjafjallajokull.
Volcanologist Steve Blake, who was unable to fly to Iceland as planned Tuesday, said the risks are real.
When ash density is high, “the air gets sucked into the engine and stops the engines,” he said.
“The more particles [there are], the riskier it is,” Mr. Blake said. “If you are flying for a short period through any given density, it isn’t so bad as flying through any given density for a long distance.”
The amount of ash spewing from the volcano tapered off dramatically Tuesday, Elin Jonasdottir, a forecaster at Iceland’s meteorological office, told the Associated Press. Because the plume’s height has decreased to about 16,000 feet, she said, the ash won’t travel far and most likely will fall to the ground near its source.
Meanwhile, the airlines are starting to chafe.
Ryanair CEO Michael O’Leary said air travel authorities are overreacting. He said the budget airline conducted its own one-hour “verification flight” over Scotland and demanded that airspace over the United Kingdom reopen.
• Amanda Brown reported from Kent, and Jason Walsh reported from Dublin.
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