Well, there we go, KLM starts flying commercially tonight. No passengers, only freight, but still. According to the CEO European airspace is safe with the exception of parts between Iceland and Russia.
Hope the rest follows soon
He might have a biased view though?
NATS and the other ANSP's don't want this to continue as much as the airlines don't. They are losing money by the day aswell. Its silly for anyone to suggest otherwise. They restricted the airspace on the basis of what science there is and the met data available. Its not their fault that there is very little science available. The countries that do regularly deal with volcanos and ash clouds haven't done any because they have the available airspace to fly round them, which isn't possible in western europe. And there is no data availble on how ash affects jet engines because no research has ever been done beyond very basic stuff in response to previous incidents. Noone knows how dense or big the particles have to be in order to stop an engine, they only know that it can happen.
All the ANSP's went for the safest possible cause of action based on the information that they had, which is the whole point of of the ANSP, to provide the safest possible air traffic service they can. It is then up to the regulators, CAA, ICAO, etc and the various governments to decide when it is safe to fly.