LEGIONS of late-running air travellers know the phenomenon all too well. The person in front of you on the travelator is walking maddeningly slowly. Have a little sympathy, though: it's not their fault. People naturally slow their pace when they step onto a moving walkway, as the story on page 11 explains. Using the travelator will save a tired traveller energy. But if your flight is already boarding, avoiding a crowded walkway could be the difference between making that flight and going nowhere. You might be better off just running for it.