this is a good (and freely available) introduction to the type of procedure employed at the various VAACs
Thanks to simonpro for the link.
However, the presentation includes:
The use of last generation models would improve notably the
confidence of the Volcanic Ash Advisory Center (VAAC) forecasts
I wonder whether the modelling version and other technology used by VAACs is now the best and latest? Or maybe it's the usual bureaucratic problem of progress only at the speed of the slowest (given that they ALL must use the same system to produce consistent results).
Either way, it still seems that there is no remote sensing technology that gives dependable information about average particle SIZE and DENSITY of ash per cubic metre of air over a large geographic area (eg. UK and Ireland).
Sorry to keep mentioning this..... but it's up to the operators to collect and pool data post-flight about ash encounters, so that there is at least a backstop for imprecise modelling, if not a method to calibrate the model in near real-time.
Given the wind forecast for the rest of this week, it looks like the industry is going to get ANOTHER wake-up call (as if it should need one!!!). Now it all depends on the volcano.
Pity CAA / EASA / ??? have not seen fit to issue any directive including data collection and sharing.