Given that volcanic activity is know to be a problem to air travel, that iceland is a very active island upwind of Europe and that there was NO orchestrated, pre-planned response to measure the cloud and refer to established and agreed levels of risk then the airline industry, aviation bodies and governments are at least lazy if not incompetent.
That there isn't some organisation or another coming out of the woodwork saying "I told you so" is also surprising, perhaps researches thought that the airline industry could look after itself?
Could it be perhaps that the closure of airspace was indeed the planned response, and that all that was lacking was adequate
PR. Could it possibly be that the Met Office, NATS and these VAAC units did indeed do their jobs based upon the skills they thought they needed?
There are valid accounts (and air samples) of some real volcanic rubbish in UK skies over the past 4 days. Don't you suppose that this validly supported a framework, using models, that provided forecasts that this cloud remained dangerous.
Here's my point: I'm conservative, and don't know much about volcanoes. The vulcanologists seem to be doing their job in conjunction with the Met Office, and NATS have made a reasonable decision on the basis of that to protect flight safety.
I can't understand the cavalier attitude here when so few are clearly experts, and the evidence to err to conservatism is rather obvious.
My analogy would be that many posters on here would think it OK to takeoff on a heavy flight from Singapore with the torrential rainstorm starting rather than waiting for 10 minutes at the threshold, simply as the last man got away with it. I have but one life.
ReHeat
But that is the real question we can all see the billowing solid black clouds at the point of the eruption and no one would want to touch that.
But 2 Km, 20 km, 200km, 2000 km ??? downwind? at what point downwind does dispersion make a serious threat to life and limb become minimal to no threat?
I'll assume that you've not read anything on here at all as to the effect of silica in the engines of the Finnish F18s, NASA's DC8 in an earlier eruption, the air samples taken by Cranfield, the muck picked up by the Scottish heli crew, and the new evidence that World Airways picked up engine deposits on a short hop to Maastricht today...?