Dubai International airport's growth is rooted in the expansion of Emirates Airline, the state-controlled carrier that was established in Dubai, part of the United Arab Emirates, in 1985.
Emirates is now operating the world's largest fleet of long-haul passenger jets, and is considering moving to a new, bigger hub in Dubai.
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Heathrow Airport Holdings said the loss of the airport's status as busiest international hub lent weight to its calls for a third runway.
"Britain has benefited from being home to the world's largest port or airport for the last 350 years . . . But lack of capacity at Heathrow means we will shortly lose our crown to Dubai," said John Holland-Kaye, Heathrow's chief executive.
Gatwick dealt with 38.1 million passengers last year, up 7.6 per cent compared with 2013, with strong growth on its core European routes.
"Gatwick's record-breaking figures show an airport serving the widest range of travel and airline models — exactly what is needed from the decision about the UK's next runway," said Nick Dunn, Gatwick's chief financial officer.
Capacity constraints hurt the punctuality of both Heathrow and Gatwick. Heathrow ranked 111th and Gatwick came 139th in a global survey of airport punctuality by OAG, the aviation data provider.
At Heathrow, 75.5 per cent of flights took off within 15 minutes of the scheduled time last year, while Gatwick achieved just 60.1 per cent.