Gatwick airport laid out a cheaper and faster solution to London's passenger capacity crisis on Tuesday, outlining how a second runway at its south London site would cost just 9 billion pounds ($13.8 billion) and be up and running in just over a decade.

After attempts to expand the city's biggest airport, Heathrow, ran into local opposition, Britain's Conservative-led government set up an independent commission to examine proposals and report back after the next parliamentary elections in 2015.

The competing lobbies have launched their detailed solutions to the issue, with Gatwick, the city's second largest airport, the latest.

The cheapest option put forward for a third runway at Heathrow would cost 14 billion pounds and be ready by 2025 at the earliest.

Expanding another smaller airport to the north of the city, Stansted, would cost an estimated 10 billion, while Mayor Boris Johnson's plans for a new four-runway hub to be built either east of central London on the Isle of Grain or further out in the Thames Estuary on a man-made island by 2029 would cost at least 50 billion.

Gatwick, owned by Global Infrastructure Partners, said a new runway south of its existing site 30 miles south of London would help reduce the city's dependency on Heathrow as a big hub airport.

"Other world cities, including New York, Tokyo, Paris and Moscow, also operate a multi-airport or 'constellation' system, and handle greater numbers of passengers than cities relying on a single 'hub'," chief executive Stewart Wingate said.

The project would be privately financed, he said, and could be up and running by 2025.

The government and business want to expand flights to fast-growing economies to ensure Britain doesn't miss out on billions of pounds of trade. With Heathrow, London's biggest airport, operating at 99 per cent capacity, more runways are needed.

Gatwick presented three options for an additional runway, which can be used in different ways. It also claims its proposals would have a much lower noise footprint than a three-runway Heathrow, affecting fewer than 5 per cent of the people Heathrow impacts today. - Reuters