Air traffic over northern Germany is returning to normal after being disrupted by volcanic ash from Iceland.
Planes are once again taking off from and landing at Hamburg, Bremen and Berlin airports after they closed for several hours.
About 700 flights were cancelled in Germany on Wednesday, Europe's air traffic agency Eurocontrol said.
The activity at Iceland's Grimsvotn volcano, which erupted at the weekend, appears to have stopped.
The German authorities closed Bremen and Hamburg airports in the early hours of Wednesday. Traffic at Berlin's airports was halted at about 1100 (0900 GMT).
Flights in and out of Bremen and Hamburg resumed in the middle of the day, when the German air traffic control agency said the ash level was "no longer critical".
Berlin was the last major centre to re-open its airspace, at 1400 local time (1200 GMT).
There are no flight restrictions elsewhere in Europe, Eurocontrol said.
Earlier, German Transport Minister Peter Ramsauer told public television ARD: "Security is the top priority but we can say that the situation will get better later today."
The country's transport authorities have taken a tough view on the potential dangers posed by the ash, says the BBC's Stephen Evans in Berlin.
There has been no outright criticism of the decision from German airlines, but there is unease in the industry that Germany's rules regarding flying through volcanic ash are different from the rest of Europe, our correspondent adds.
The head of the country's airport organisation said Europe-wide rules were needed.
France's civil aviation authority has said it expected very little disruption to air traffic and was not expecting to close any of the country's airspace.
Air traffic in Norway, Denmark and the UK was disrupted on Tuesday, with about 500 cancellations. Scotland, Northern Ireland and northern England were especially badly hit.
The UK closures were condemned by Ryanair chief Michael O'Leary on Tuesday. He accused authorities of "bureaucratic incompetence" and said the airline had safely sent two planes into ash zones over Scotland.
Britain's weather service said the concentration of volcanic ash in UK airspace would decrease significantly over the course of Wednesday.
The volcano began erupting last Saturday, sending clouds of ash high into the air. But it appeared to have stopped emitting ash at 0200 GMT on Wednesday, said Hrafn Gudmundsson of the Icelandic Meteorological Office.
Experts say the eruption is on a different scale to that of the Eyjafjallajokull volcano last year, when millions of travellers were stranded amid concerns about the damage volcanic ash could cause to aircraft engines.
European Union transport commissioner Siim Kallas said: "We do not at this stage anticipate widespread airspace closure and prolonged disruption like we saw last year."
Icelandic President Olafur Grimsson told the BBC: "The eruption is gradually being diminished and the ash cloud is definitely smaller than it has been so we are pretty optimistic now."
The ash particles from Grimsvotn are larger than those from Eyjafjallajokull, and so fall to the ground more quickly.