silverstrata,
reading your numerous posts, including, most tellingly, the one above it appears to me that you will rubbish any evidence unless it points to opening airspace. You dismiss the environmental aircrafts findings, yet are happy to take a couple of flights by BA, KLM etc, which have no on board sensors as proof that everything is safe.
You dismiss the F18 engine degradation because the engines had not had a thorough inspection for 3 months (your statement that the engines had not been inspected for 3 months wrong and misleading) - the fact that the damage would have been visible on a normal 25 hour servicing schedule (or whatever period the Finn mil use) is probably not enough evidence for you either no doubt...
There is a very high possibility that there has been an unwarranted level of airspace closure over this volcanic activity, but for anyone to call it a 'knee jerk reaction' or such is completely wrong. A knee jerk reaction would be an action/measures taken that went beyond internationally accepted procedures.
In the case of the UK, NATS have sanctioned IFR flying in airspace as and when the charts have shown a clear window (look back at the scottish airspace for example). NATS and other ANSPs are acting on instructions and procedures laid down by governing bodies, and to a certain extent are being given no guidance by those above.
This 're-opening' and 'closing' of airspace is evidence that the ANSP is working to the rules it is governed by, not 'over reacting'.
The fact the rules may be outdated is another matter. ANSPs do not write the rule book in these instances, however they must follow it.
It is up to the governing bodies to allow a relaxation of these (no doubt archaic) rules. The ANSP of the country can only do what is laid down - to do otherwise is illegal.
Finally, people talk about the fact that aviation has always involved 'risk'. That is 100% correct - even today in normal operations there is a level of risk that is mitigated against. However this 'risk' has been analysed and assesed and then deemed acceptable.
The FACT of the matter is, there is not enough data available to do the same with volcanic ash - the risk is unquantifiable and unfortunately that's not good enough for modern aviation... therefore using the argument 'flying always contains an element of risk' is complete tosh in this instance.
Yoganmahew
To claim that because this started on Thursday night and therefore a solution has been slow in coming because people have been away for the weekend is the most ridiculous and ignorant statement yet.
There have been continual high level meetings about this since Thursday evening.