All options for airport expansion are "back on the table", the man charged by the Government with recommending future aviation policy has said.
There was "no clear consensus" on the best way forward for UK airports, said Airports Commission chairman Sir Howard Davies. He said his commission would try to produce a final report by summer 2015 which would give the government of the day the opportunity to make decisions quickly.
Speaking in London as he introduced his five other commissioners, Sir Howard said he was aware of the criticism of some, including London Mayor Boris Johnson, that the commission's 2015 timescale was too long.
Sir Howard said: "The arguments are well understood. Some are political, some are not. What we are trying to do is to make sure the work we do is useful and allows decisions to be made more quickly."
Labour had been keen on a third runway at Heathrow Airport but on coming to power in 2010 the coalition Government ruled this out. Mr Johnson supports a new Thames Estuary airport while architect Lord Foster has submitted his own estuary airport plan. Asked if everything was back on the table, Sir Howard replied "yes".
He said options his commission would be looking at in addition to the main ideas included possible further use of Birmingham Airport if the HS2 rail link goes ahead, and a so-called Heath-wick plan, in which a fast rail link between Heathrow and Gatwick would enable the two airports to be regarded as a twin hub.
It will also examine the possibility of Cardiff Airport being regarded as Heathrow's "sixth terminal" when fast rail links are completed, and a plan to "move" Heathrow westwards which includes putting part of the M25 in a tunnel.
Transport Secretary Patrick McLoughlin said: "Aviation is vital to the UK economy and we need to have a long-term aviation policy which meets the challenges of the future. Sir Howard and his team will now take forward this vitally important work for the Government and bring a much-needed fresh perspective to the debate."
Under a local agreement, no extra runway can be built at Gatwick before 2019, although expansion at the West Sussex airport will be among options looked at by the Davies Commission. Gatwick chief executive Stewart Wingate said: "We welcome today's launch of the commission. A new runway at Gatwick could be more affordable and practical than other options and give passengers a greater choice of routes to key destinations."
A Heathrow spokesman said: "We hope the Davies Commission will build consensus on the UK's requirements for hub capacity and then rigorously assess every option against those needs. None of the options for hub airport capacity is easy. Every choice, including doing nothing, has its consequences. However, a clear positive decision would stimulate economic growth, create jobs, and help secure Britain's competitiveness in a changing world."