Eurocontrol, the European air navigation and safety organization, says by the end of Sunday more than 63,000 flights will have been canceled since April 15.
Of around 24,000 flights that normally operate on a Sunday only some 4,000 will fly, Eurocontrol said.
U.K.: All airspace closed until at least 1300 GMT Monday.
Ireland: All airspace closed until at least 1200 GMT (8 a.m. EDT) Monday.
France: All airspace north of an axis between Nice on the Mediterranean and Bordeaux near the Atlantic will remain closed through 8 a.m. (0600 GMT) Tuesday. Air France tried five evaluation test flights Sunday. Airports in Marseille, Nice and Toulouse remain open through Monday.
Germany: Air traffic control slightly loosened its ban on flights from the country Sunday, temporarily allowing some traffic at Frankfurt and airports in the north. Flights were allowed from the Frankfurt hub and the smaller Hahn airport nearby until 8 p.m. (1800 GMT) -- but only for planes heading to some destinations to the north. They -- along with the airports in Hannover, Erfurt and Leipzig, which also were cleared for limited operations Sunday afternoon -- will then be closed again until at least 2 a.m. (0000 GMT) Monday. The two Berlin airports were allowed to operate until 10 p.m. (2000 GMT) Sunday -- but only for some planes headed eastward. All other German airports, including Munich, remained closed.
Austria: Airports closed until at least 0000 GMT (8 p.m. EDT Sunday). Overflights at or above 26,000 feet (8,000 meters) are allowed.
Belgium: Belgian airspace closed until at least 0600 GMT (2 a.m. EDT) Monday, but likely to decide then whether to let fleets reposition empty aircraft for traffic when service resumes.
The Netherlands: All airspace closed until at least 1200 GMT (8 a.m. EDT) Sunday.
Switzerland: Airspace closed until at least 1200 GMT (8 a.m. EDT) Monday. Planes using instruments can fly across Switzerland as long as they stay above 36,000 feet (11,000 meters).
Italy: Airspace in northern Italy closed until 0600 GMT (2 a.m. EDT) Monday.
Spain: reopened all its airports at 1330 GMT (10:30 a.m. EDT). Flights to all European destinations except Portugal, south Italy, Greece and Istanbul remain closed. Flights to north and south America operating normally.
Sweden: Airspace closed in southern Sweden, including Stockholm. Air travel permitted north of the city of Soderhamn in central Sweden.
Norway: authorities have lifted air travel restrictions in most parts of central and northern Norway down to Bergen. Airspace in the far north and south, including the capital, remain closed but Oslo's Gardermoen airport could open during the evening.
Iceland: flights to UK and mainland Europe suspended indefinitely; flights to U.S. operating normally.
Bulgaria: reopens airspace for overflights above 26,000 feet (8,000 meters). Airports in Sofia, the capital, and the southern city of Plovdiv were temporarily reopened Sunday afternoon, but flights to all European destinations except Cyprus, Greece and Moscow remained closed.
Slovakia: Airspace closed until at least Sunday evening.
Russia: Russian airlines are canceling flights to various points in Europe, but Russian airspace remains open.
Croatia: the country's airspace reopened mid-Sunday except small Osijek airport in the east. Flights from Split and Dubronvik to Madrid and Rome are on, as well as domestic flights.