There seems to be many comments about airspace closure as per last years event. The big change is that this time around the airlines are responsible for whether they fly or not.
The shakedown after the last occurrence showed that the ATC providers do not have the prerogative to shut down airspace. The airlines are required to submit a risk assessment to the CAA on the levels of ash that they are able to fly through. It would seem most airlines are Cyan - OK, Grey - OK, Red - No Go.
This time around we shall stil have disruption, but a far more fluid situation than last years complete halt. Routes will cease while the threat is present, then reopen.
Another factor is that during the last event, differing forecasting outfits came up with very different results. The UK Met office was deemed to have a very conservative outlook, whilst WSi, which some UK airlines were using, came up with a very different threat level. This year the two forecasts appear to be much better aligned.
Glad I'm on leave though!