City pair

In commercial aviation, a city pair is defined as a pair of departure (origin) and arrival (destination) airport codes on a flight itinerary. A given city pair may be a single non-stop flight segment, a direct flight with one or more stops, or an itinerary with connecting flights (multiple segments). The city pair, IAD-LHR would consist of flights and/or multi-leg itineraries that originate at Washington-Dulles airport and terminate at London-Heathrow airport. The city pair, NYC-TYO would consist of flights and/or multi-leg itineraries that originate at any New York airport (New York-JFK, Newark-Liberty or New York-LaGuardia) and terminate at either Tokyo-Narita or Tokyo-Haneda.