Where do these "decisions" originate
Try comparing the airports open with the UK met office ash cloud forecasts. I see a remarkable resemblence although the forecast is altitude specific.
What I think we need, and probably sooner rather than later given that Iceland is a string of volvanoes, is a means to establish ash risk v. altitude and time. With what we know, I can understand DLH flying under the ash in dry air, I have difficulty understanding KLM apparently flying through it.
If I was head of an airline I would put up a lot of money into Qinetiq/Cranfield/DLR etc to take air samples a.s.a.p. We can't afford to wait for governments to get back to work on monday, and then have indecision from lack of info.
DLH, how high can yr Junkers climb? Maybe you can do it yourselves!