But a total shutdown of aviation? Without any scientific debate on concentration levels and dispersion?
Just because you are not involved in the debate does not mean it is not happening. I got 3 hours sleep last night because I was busy trying to provide the relevant people with high quality data regarding the ash. I've spent all day today dealing with calls and emails from scientists wanting information about how well some satellite sensors that I worked on can detect the ash. There is plenty of debate about it, and this debate will continue.
I'm afraid the "better safe than sorry" attitude does not cut it. Because the apparently safe decision may and will have unforeseen aftereffects that may be quite detrimental to safety levels. Like a lack of trust in the next stern warnings. One can only shout "wolf" so often before it becomes ineffective.
So you'd rather that the NAT etc close the stable door after the horse has bolted?
Frankly that is a reckless and dangerous attitude to take. Do you need an accident to happen just to prove that this ash is a problem?