Avent points to various economic forecasts and posits:
The airlines will feel significant pain from this event, though the impact will differ from that after September 11 in that fear of terrorism continued to reduce traffic volumes after the flight disruptions ended. Should flights resume this week or next, the hit to output probably won't be that significant, especially since there are some offsetting effects to lost airline activity (hotels, train operators, and car rental firms are all having banner weeks). But if most flights are still grounded by mid-May, the fallout could be significant. Mother Nature does love to throw economic curveballs.