Slow down! The shut down halted most flights – not all as the rich continued with their private planes (of which about 50% of flights have no passengers!!). As planes are a major source of pollution this has to be a good thing. But people need holidays, and the cultural benefits of foreign travel are invaluable. A conundrum. Maybe shorter journeys abroad by train, and flights that are powered by electric planes (yes the technology is getting there), will be the way to go.