A few weeks ago, nobody who wasn’t living literally in the shadow of a volcano was giving much thought to the impact that a volcanic eruption could have on their lives. Of course, that was before the volcano-nobody-could-pronounce erupted in Iceland, shutting down air traffic in Europe for several days. Would-be travelers were faced with a choice between sitting tight in London (or wherever) and reading a book or sightseeing, or else hopping a train to race south and attempt to fly out of a different airport. For most travelers, it was a relatively minor inconvenience and perhaps a bit of unplanned expense. For the airlines, it would certainly have had a much bigger impact.