I find it troubling how many supposedly educated, professional pilots still can't grasp that the reason for such a severe clamp down last time was not just because modern aircraft are designed to tighter limits than old, the technology changing as much as its susceptibility tot he ash, but more critically that the highly idiosyncratic circumstances of the eruption made the ash particularly hard to observe and simultaneously particularly threatening to engines. Comparisons to other events only serve to demonstrate those individuals' lack of comprehension of the technical elements of the event. Equally troubling is their blind dismissal of the tests carried out by several military aircraft which were subsequently found to have significant engine deposits and damage.