I just want to say as an ATCO..respect to those pilots who have flown today...basically through the unknown....no matter what all the 'experts' say...nobody knows what could happen and still you went to work! Have to say even on the ground it felt a bit strange.... esp giving pilots VFR clearance and then IFR passing fl200...later Fl250 (in Germany)....so respect and well done!! Not sure I would have been so brave!!
The pilots operate with at least some knowledge of the risks involved. The same is not true for any passengers they carry, who simply trust pilots and the airline operator to maintain the highest level of safety. And unfortunately, as long as there is ash in the air, the usual highest level of safety is not being maintained, although the revenue stream of airlines is being maintained. Recent events have shown that there is no danger that cannot be ignored if there's enough money at stake.
Fortunately nature has cooperated slightly and the ash concentrations seem to be diminishing. Hopefully nobody will be killed by airline greed on this pass, but only time will tell.