First type in an airport using the city or airport name or IATA code (over 3000 airports available) and choose it from the drop-down box. Then, name all the destinations served by routes from that airport. Destination distance shown. You are typically naming the destination cities (typically the large city associated with the destination airport, not necessarily the exact city where the airport is located, occasionally the answer may be a small island instead of a city name), but occasionally I will also allow an airport name.