REYKJAVIK, Iceland, April 19 (UPI) -- Airlines sent test flights through a volcano ash cloud hanging over Europe to determine whether it was safe to resume commercial aviation flights.
Hundreds of thousands of travelers have been stranded by governmental actions that closed airspace because of the cloud spewed from the Eyjafjallajoekull volcano in Iceland. Airports across Europe were closed Monday, many for a fifth day.
Flying through a volcanic cloud can cause a plane's engines to fail, a threat that led officials to suspend flights. It was expected that only about one-third of the usual 8,000 European flights would be in the air Monday.
Most airports across the northern tier of the continent were closed but even as far south as Rome and Madrid the number of flights was limited.
With major airports closed, governments resorted to innovative methods to get their citizens home -- the British navy is using three warships to ferry Britons from mainland Europe to England, for example. In the United States, Europeans in Florida without a way home were offered a free visit to the SeaWorld theme park.
The head of the International Air Transport Association told the BBC the flight ban was costing airlines $200 million a day. He was sharply critical of government decisions to so severely limit flights.