Don’t call it a comeback: While most travel has gone back to normal after shutting down because of a cloud of volcanic ash, the airspace over Scotland and Ireland was closed Monday night as ash drifted south. “The decision is based on the safety risks to crews and passengers as a result of the drift south of the volcanic ash cloud caused by the northeasterly winds,” said the chief executive of the Irish Aviation Authority, which made the decision in conjunction with the Civil Aviation Authority in the U.K. Some 440 flights have so far been grounded but are expected to depart after delays. Flights elsewhere in the U.K. and Europe have not been affected aside from minor delays, and authorities will reassess the flight ban over the course of Tuesday morning.