City pair 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
Washington Dulles International Airport mezzanine with more room for lines. A new train system, dubbed AeroTrain and developed by Mitsubishi, began in 2010 to transport passengers between the concourses and the main terminal. The system, which uses rubber tires and travels along a fixed underground guideway, is similar to the people mover systems at Singapore Changi Airport, Hartsfield–Jackson Atlanta International Airport, and Denver International Airport. The train is intended to replace the mobile lounges, which many passengers found crowded and inconvenient. The initial phase includes the main terminal station, a permanent Concourse A station, a permanent Concourse B station, a permanent midfield concourse station