All options for airport expansion are “back on the table”, the man charged by the Government with recommending future aviation policy said today.
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."
He went on: "The coalition Government is prepared for us to look broadly at all the options on the table as well as some that are not on the table so that a government can come to it after the General Election with an open mind."
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.
:: 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.
:: Cardiff Airport to be regarded as Heathrow's "sixth terminal" when fast rail links are completed.
:: A plan to "move" Heathrow westwards which includes putting part of the M25 in a tunnel.
Sir Howard has been charged with bringing out an interim report by the end of next year which will include recommending actions to improve the use of existing runway capacity to cover the period of the next five years.
He said today that this first report would include a narrowing down of options "that look credible and worthy of further examination".
Sir Howard said that since his appointment by the Government in September, "we have seen a flooding of (aviation) ideas and initiatives from all over the place".
The commission members include former Network Rail and Olympic Delivery Authority chief Sir John Armitt as well as Manchester Airport Group boss Geoff Muirhead.
Sir Howard said he very much hoped Labour would co-operate with his commission, that no members of the commission had any particular airport expansion preferences and that it was "a bit harsh" to say the commission was "business-biased".
He went on: "I don't think there is a good enough consensus on aviation policy for the Government to make a decision now.
"Maybe I'm being a bit indulgent towards them (the Government) but this is a very difficult subject. There is a strong case for a commission which tries very hard to rebuild a consensus for what we need in this country."
Sir Howard promised that before the commission brings out its first report it would publish the first of what are expected to be a series of consultation papers - with the first being about aviation demand forecasts.
He said other papers could include the subject of airport noise and compensation for it, and climate change. He promised that there would be public meetings on various topics.
Sir Howard said he was aware of those who said the commission was the way for the Government to kick the subject of aviation into the long grass.
He replied: "Some of the criticism assumes that we will go into a huddle for a couple of years and then come out with 'X solution'. It's not going to be like that."
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. The detailed work and analysis on how to maintain the UK's status as an international aviation hub can now really begin.
"At Gatwick, we have already announced that we are beginning detailed studies on the options for a second runway. We know that Gatwick can play a critical role in addressing the current and future capacity problems in south east England.
"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.
"At Gatwick, we have the space, the capability and the access to financial resources. Critically, we would have a significantly lower environmental impact when compared, for example, to a third runway at Heathrow."
Corin Taylor, senior economic adviser at the Institute of Directors, said: "Sir Howard is obviously doing the best he can with the hand he was dealt, but the Government must look again at the excessive length of time before they allow him to report.
"The uncertainty already caused by years of delay on airport expansion is damaging enough without waiting even longer to make a decision.
"It seems that the Davies Commission will have solid conclusions based on extensive research ready well before 2015 - business needs to know what they are as soon as possible. We must remember that airports are not standalone installations - delaying this question for three years will have knock-on effects on surface infrastructure like rail connections."
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."
Prime Minister David Cameron's official spokesman denied the issue had been kicked into the long grass, saying it would take "time and work" to address the issue.
Asked about the London mayor's concerns, he said: "People on different sides of the debate have particular entrenched views.
"Often those different options and different ideas about how we should apporoach the issue of airport capacity are put forward without the evidence."
The commission would enable a "proper and informed" debate.