Flights at UK airports returned to normal today after high levels of volcanic ash from the Icelandic eruption cleared UK skies.
But airlines, including British Airways, had to axe some German services as the ash cloud moved over northern Europe.
And there were also concerns that high ash densities could return to the UK on Friday as the bank holiday getaway begins.
Air traffic control company Nats said UK skies would be clear of high levels of ash until at least 7pm today.
The all-clear followed the axing of a number of flights from Scottish airports yesterday and also from Newcastle airport as high levels of ash hung over Scotland and parts of northern England.
Also from Berlin
Berlin airports will close as of 0900 GMT Wednesday because of danger posed by ash pouring from an Icelandic volcano, Germany air safety officials announced.
The leading German airline, Lufthansa, had earlier said it expected to cancel about 150 flights Wednesday because of the ash cloud which on Tuesday had forced the closure of Northern Ireland and Scottish air space.
Operations at Tegel and Shoenefeld airports would halt operations from 11:00 am (0900 GMT), air safety officials said.
In Hamburg, the country's second biggest city, there had been no take-offs or landings since 6:00 am (0400 GMT), an airport spokesman told AFP.
He was unable to say how many of the airport's 453 daily flights would be affected however.
In Bremen, another northern German port, traffic was halted since 05:00 am (0300 GMT) and service by the German flag carrier Lufthansa was cancelled until 04:00 pm (1400 GMT), an airport spokesman said.
Low-cost airline Ryanair had done the same until 11:00 am (0900 GMT), he added. Bremen normally sees around 100 flights per day.
German Transport Minister Peter Ramsauer told public television ARD the situation was expected to improve later in the day.
"Security is the top priority but we can say that the situation will get better later today," Ramsauer said.
Problem switched to Germany. British Airways cancelled one London-Hamburg and two Hamburg-London flights today and budget carrier easyJet also axed some German flights.
EasyJet said Hamburg airport would be closed until 2pm UK time and Berlin's Schonefeld and Tegel airports were also expected to be shut this morning.
EasyJet added that more of its flights could be cancelled later.
Ryanair said it had axed all its flights in and out of the German airports of Bremen, Lubeck and Magdeburg until 1pm UK time.
