Northern Virginia from the older National Airport (a focus city for American Airlines) are restricted for distance, frequency, and flight paths due to the proximity to federal facilities, Dulles is the region's second busiest airport in both passenger loadings and aircraft movements, and the sixteenth-busiest airport in the United States by takeoffs and landings in 2007. Dulles is the region's primary international gateway, serves as a hub for United Airlines, and has recently improved its low-cost carrier offerings with the addition of multiple flights by Southwest and JetBlue. Commuters are served by the Washington Metro subway and the Virginia Railway Express, a
London City Airport Authority. London City Airport has a single long runway, and a CAA Public Use Aerodrome Licence (Number P728) that allows flights for the public transport of passengers or for flight training (but only for training necessary for the operation of aircraft at the airport). Only multi-engine, fixed-wing aircraft with special aircraft and aircrew certification to fly 5.5° approaches are allowed to conduct operations at London City Airport. The largest aircraft which can be used at the airport is the Airbus A220-100. London City served over 4.5 million passengers in 2017. It is the fifth-busiest airport in passengers and aircraft movements