Media playback is unsupported on your device Media caption Speeded up video from flightradar24.com of an hour of plane movements over south-east England

New runways at Heathrow and Gatwick are among the options that have been short-listed by the Airports Commission for expanding UK airport capacity.

The three short-listed options include adding a third runway at Heathrow, lengthening an existing runway at Heathrow, and a new runway at Gatwick.

The commission, led by businessman Sir Howard Davies, will also consider a new airport in the Isle of Grain in north Kent.

A final report is due by summer 2015.

Media playback is unsupported on your device Media caption Sir Howard Davies sets out the airport expansion options

The commission has not shortlisted proposals for expanding Stansted or Birmingham, but said there was likely to be a case for considering them as "potential options" for any second new runway by 2050.

Sir Howard was asked in 2012 to investigate the options for expanding the UK's aviation capacity and try to come up with a plan.

He said the Commission's analysis showed one net additional runway was needed by 2030.

"The capacity challenge is not yet critical, but it will become so if no action is taken soon," he added.

Analysis There are four interesting elements of today's report. It's Heathrow-heavy. It hasn't written off the ambitious, expensive idea of building a new mega-airport on the other side of London in the Thames Estuary. It misses off Stansted, despite it being picked for expansion by the last government. Stansted lost a lot of passengers in the recession. It also suggests that we might not need one huge hub airport after all, because all the growth in recent years has come from low-cost carriers. In a nutshell, it makes the case stronger for a bigger Gatwick. When I first took over the transport job, about two years ago, the government told me straight away that it would not expand Heathrow. One of the first things the coalition did when it came to power was to cancel Labour plans for a third runway at the airport. I've gone through my old notebooks and found this phrase written down, "dead and buried". But after a great deal of lobbying from the airport's owners, other business leaders, airlines and the unions, as well as support from the Transport Select Committee, Heathrow is emerging once again, as a front-runner in the fight to get a new runway. Sir Howard has set a deadline of 2030. But believe me, there are plenty in the industry - like Willie Walsh at British Airways, for example - who still don't think that in the end, anything will actually ever get built.

The Commission has short-listed the following proposals to investigate ahead of its final report:

A new runway at Gatwick Airport more than 3,000m in length

A new 3,500m runway at Heathrow Airport constructed to the north-west of the existing airport

An extension of Heathrow's existing northern runway to the west to at least 6,000m, enabling it to be used for both take-offs and landings

Media playback is unsupported on your device Media caption Boris Johnson: Third Heathrow runway "would be crackers"

The Mayor of London, Boris Johnson, has said that putting a new runway at Heathrow would be a "catastrophe".

Following the commission's report, Mr Johnson said he continued to support the creation of the Isle of Grain airport in north Kent.

"A new airport in the inner estuary is the only credible hub option left. By keeping it on the table, Davies is saying you have a choice - between a damaging U-turn or a radical new vision for expansion," he said.

In its report, the Commission calculates an Isle of Grain airport would cost up to £112bn - around five times that of its three short-listed options.

However, it said it would look at it in the first half of 2014, to reach a view on whether the option offered "a credible proposal".

"The overall balance of economic impacts would be uncertain - particularly as an Estuary airport would require the closure of Heathrow for commercial reasons and London City for airspace reasons," it says.

Meanwhile, supporters of Heathrow's expansion say it will be quicker and cheaper than other options and will help to maintain the UK as an international aviation hub.

Heathrow's owners submitted evidence to the commission arguing that a new runway could be in place by 2029, allowing 260,000 more flights.

Keeping the banking system solid and sound looks a rather more important priority than whether or not Heathrow gets a new runway or the London Mayor builds his vast new flying city on the Isle of Grain

Colin Matthews, Heathrow chief executive, told the BBC: "The case for Heathrow is strong. It's important that businesses can get around the globe to where economies are growing.

"We've got Paris and Amsterdam, Frankfurt desperately trying to eat our lunch, they want to have the business that the UK benefits from today."

John Cridland, head of business lobby group the CBI, said that urgent action was needed from the government when the commission's final recommendations were made in 2015.

"It is no longer acceptable to bury our heads in the sand on this," he added.

Heathrow is one of the world's busiest hub airports, handling 70 million passengers in 2012.

But the airport operates at 98% of its capacity.

When the coalition government came to power in 2010, it scrapped the former Labour government's plan for a third runway at Heathrow.

The government said on Monday that it had not ruled out any options when it came to airport expansion in the south-east of England.

Image caption Gatwick identified three options for a second runway, but the Davies Commission shortlisted Option 3, which would allow fully independent operation.

On Sunday, Transport Secretary Patrick McLoughlin said that the government would stick to its pledge not to build a new runway at Heathrow before 2015.

He told the BBC: "We will not be building a third runway in this Parliament. We will stick by our manifesto commitment."