Flights were suspended at Frankfurt airport, Europe's third-busiest terminal, and at other German airports including Duesseldorf, Berlin, Hamburg, Munich and Cologne.
Irish aviation authorities reopened airports in Dublin and Cork and France allowed some planes to land in Paris. Sweden and Norway declared skies in the far north to be safe but kept a lockdown on flights to both capitals -- Stockholm and Oslo.
Britain's National Air Traffic Service said the air over England would remain closed to flights until at least 7 a.m. (0600 GMT, 2 a.m. EDT) Saturday, although some flights were being allowed in Northern Ireland and Scotland.
Switzerland, Slovakia, Croatia and Hungary closed their airspace, and Poland expanded its no-fly zone to most of the country, excluding Krakow. Belgium extended its flight restrictions until late Saturday morning.