context: London is a major international air transport hub with the busiest city airspace in the world. Eight airports use the word London in their name, but most traffic passes through six of these. London Heathrow Airport, in Hillingdon, West London, 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. There were plans for a third runway and a sixth terminal; however, these were cancelled by the Coalition Government on 12 May 2010.
question: లండన్, దాని చుట్టుపక్కల ఎన్ని విమానాశ్రయాలను ఎక్కువ శాతం ఎయిర్ ట్రాఫిక్ ఉపయోగించుకుంటుంది?
answers: six