Two key air travel groups issued a joint statement pushing authorities to ease flying restrictions. Airports Council International (ACI) Europe, which represents airports, and the Association of European Airlines (AEA) said they question "the proportionality of the flight restrictions currently imposed."
But an expert who has flown into the skies to check conditions said he believes it will be "a few days yet" before it's safe to fly.
A spokeswoman for KLM, one of the airlines that conducted test flights, told CNN the flights show European airspace is safe, with the exception of Iceland. CNN's Gary Tuchman in Iceland reported that there were airspace problems in eastern Iceland. In the capital, Reykjavik, flights were taking off and landing.
British Airways, which conducted a test flight Sunday, said "conditions were perfect and the aircraft encountered no difficulties." The plane will undergo "a full technical analysis" next.
