London by air

London is a major international air transport hub with the largest city airspace in the world. Eight airports use the words London Airport in their name, but most traffic passes through one of five major airports. London Heathrow Airport is the busiest airport in the world for international traffic, and is the major hub of the nation's flag carrier, British Airways. In March 2008 its fifth terminal was opened,[184] and plans are already being considered for a sixth terminal. Similar traffic, with the addition of some low-cost short-haul flights, is also handled at London Gatwick Airport. London Stansted Airport and London Luton Airport cater mostly for low-cost short-haul flights. London City Airport, the smallest and most central airport, is focused on business travellers, with a mixture of full service short-haul scheduled flights and considerable business jet traffic.

Source: http://en.wikipedia.org/wiki/London#Air