European aviation agency Eurocontrol said no landings or takeoffs were possible for civilian aircraft in most of northern and central Europe because of the ash spewed out by the Icelandic volcano, which was still erupting.
Many countries closed airspace until today or tomorrow and weather experts forecast the cloud would not move far. They said the plume of ash could even become more concentrated on Tuesday and Wednesday, posing a greater threat to air travel.
The plume that floated through the upper atmosphere, where it could wreak havoc on jet engines and airframes, is costing airlines more than $200 million a day.
Test flights without passengers are taking place in the Netherlands and other European countries to assess the impact of the ash on aircraft, the Dutch government said yesterday.
The disruption is the worst since the Sept 11 attacks on New York and Washington in 2001, when US airspace was closed for three days and European airlines were forced to halt all transatlantic services.
Eurocontrol expected 5,000 flights in European airspace, compared with 22,000 on a normal Saturday. On Friday it said there were 10,400 flights compared with the usual 28,000.
“Forecasts suggest that the cloud of volcanic ash will persist and that the impact will continue for at least the next 24 hours,” the agency said in a statement just after 0900 GMT.
The cloud has forced several world leaders to hastily rearrange travel plans. US President Barack Obama and German Chancellor Angela Merkel and others have cancelled trips to Poland for the funeral today of Polish President Lech Kaczynksi, killed in a plane crash in Russia a week ago.
The volcanic eruption appeared to be easing yesterday but could continue for days or even months to come, officials said.
US-based forecaster AccuWeather said the ash was in an area of weak wind flow and was unlikely to move far tomorrow.
“The plume is expected to become more concentrated Tuesday and Wednesday, posing a greater threat to air travel. However, it is also expected to become narrower, impacting a smaller area,” it said, adding an Atlantic storm and change in the direction of the jetstream on Thursday could break up the cloud.
“A southwest jet stream should help clean any remaining ash plume out of most of Europe and bring some relief for the aviation crisis,” it said.