AMSTERDAM — Airlines toted up losses topping $2 billion and struggled to get hundreds of thousands of travelers back home Wednesday after a week of crippled air travel, as questions and recriminations erupted over Europe's chaotic response to the volcanic ash cloud.
Civil aviation authorities defended their decisions to ground fleets and close the skies — and later to reopen them — against heated charges by airline chiefs that the decisions were based on flawed data or unsubstantiated fears.
The aviation crisis sparked by a volcanic eruption in Iceland left millions in flightless limbo, created debilitating losses for airlines and other industries and even threatened Europe's economic recovery. An aviation group called the financial fallout worse than the three-day worldwide shutdown after the 2001 terrorist attacks in the United States.
It was a lesson in humanity's dependency on air travel, the vulnerability of a vital industry, and the confusion that can ensue when each nation decides for itself how to handle a problem that crosses borders.
The air space over most of Europe opened Wednesday after the vast, invisible ash-laden cloud dispersed to levels deemed safe. Restrictions remained over parts of Britain, Ireland, France and the Scandinavian countries.
Electronic boards in Europe's biggest hubs — London's Heathrow, Paris' Charles de Gaulle and Germany's airport at Frankfurt — showed about 80 percent of flights on schedule as airlines began filling vacant seats with those who had been stranded for days. But with 102,000 flights scrapped worldwide over the last week, it could take over a week to get everyone home.
In Iceland, the volcano under the Eyjafjallajokull glacier remained active Wednesday — throwing magma chunks the size of cars into the air, bubbling lava and producing tremors. But it was not shooting ash and smoke four to six miles into the air like it did previously.
"There is much, much less ash production and the plume is low," said Gudrun Nina Petersen, meteorologist at the Icelandic Met Office, adding that mild winds kept the ash away from crowded air flight corridors.
Civil aviation officials said their decision to reopen terminals where thousands of weary travelers had camped out was based on science, not on the undeniable pressure put on them by the airlines.
"The only priority that we consider is safety. We were trying to assess the safe operating levels for aircraft engines with ash," said Eamonn Brennan, chief executive of Irish Aviation Authority.