Heathrow needs a third runway and possibly a fourth, the head of the Commons Transport Committee has said.
The Labour MP Louise Ellman was speaking before Tuesday’s publication of the first report by the government-appointed Airports Commission, chaired by Sir Howard Davies.
As well as publishing measures to ease airports congestion in the short term, the commission will reveal a short list of extra runway options - a list expected to include expansion at Heathrow.
However, firm proposals will not be made until the commission publishes its second, and final, report in summer 2015 - after the next general election.
Mrs Ellman pointed out that her committee had, earlier in the year, come out firmly in favour of a third runway at Heathrow while rejecting a new Thames Estuary airport east of London on cost and environmental grounds.
The estuary airport plan is supported by London mayor Boris Johnson who has dubbed expansion at Heathrow as "environmentally disastrous and bad for London and the country".
Mrs Ellman's committee also concluded that bosses of Gatwick in West Sussex should be encouraged to "develop a robust business case for their vision of a second runway".
Mrs Ellman said: "The (committee's) inquiry found very clearly that Heathrow - the UK's only hub airport - has been short of capacity for a decade, is currently operating at full capacity and needs a third runway.
"We also suggested that a four-runway proposal for Heathrow might have merit, especially if locating these westwards from the current site could curb the noise experienced by communities under the flight path."
The run-up to the Davies Commission's first report has stirred passions. Labour has supported a third runway at Heathrow but expansion at the west London airport was ruled out by the coalition Government when it took power in May 2010.
Last week, Tory MP Zac Goldsmith said any decision from the Prime Minister to back Heathrow expansion would represent an "off-the-scale betrayal" and that Mr Cameron would "never be forgiven in west London."
Transport Secretary Patrick McLoughlin said the coalition's pledge was not to build a third runway "in this Parliament" and stressed any decision would come after summer 2015, when the commission is due to publish its final report.
He said the decision would be in the best interests of the UK, not just London, and pointed out that aircraft are becoming quieter and more fuel-efficient.
Today, think-tank the Institute of Economic Affairs (IEA) said airports should be able to buy the right to expand and emit more noise by paying compensation to local residents.
It added that government involvement in the debate over aviation capacity was both unnecessary and undesirable and so airports needed to be given the ability to cut deals with local residents independently.
Rather than getting involved in decisions about where to expand capacity, politicians should give airports a means to reach agreements with residents affected by their decisions.
A compensation mechanism would allow agreements that benefit both airports and those who live in their surrounds, the IEA said.
In a more radical proposal, the IEA said "tax havens" could be created around airports which pay a large proportion of local levies, allowing residents to pay lower taxes.
Baroness Jo Valentine, chief executive of business group London First, said today: "Building extra capacity, be it through more runways or a new hub airport, is vital to the UK's future prosperity.
"But even a new runway at an existing airport could be a decade away so short-term measures to increase capacity are essential."
In a speech in October this year revealing the commission's "emerging thinking", Sir Howard said: "Our provisional conclusion is that we will need some net additional runway capacity in the south-east of England in the coming decades.
"To rely only on runways currently in operation would be likely to produce a distinctly sub-optimal solution for passengers, connectivity and the economy and would also almost certainly not be the best solution in terms of minimising the overall carbon impact of flights and travel to and from airports."