 The number of planes using the airport continues to grow |
Announcing options for consultation, she said without growth the airport's status would suffer, but any expansion must meet noise and pollution tests.
Among options are a 2,200m third runway built north of Heathrow by 2020, and a sixth terminal, which will require the destruction of an entire village.
Critics say more than 50 communities and towns will suffer increased noise.
Analysis published by the government on Thursday suggests an expanded Heathrow could meet air pollution and noise limits over time.
It says three runways could be operated from 2020, without breaching air quality limits - thanks to developments like cleaner aircraft engines.
But it says take-offs and landings should be limited to 605,000 initially, to meet noise restrictions.
As older, noisier planes are phased out, this could rise to 702,000 by 2030. Currently there are 480,000 a year.
The third runway is among proposals in a consultation process which will run until 27 February.
Another is a sixth terminal to serve the new runway, which would require 700 properties to be bulldozed, including the village of Sipson, on the outskirts of the airport.
Other suggestions are allowing the two existing runways to be used for both take-off and landings, rather than the current alternation method, which would allow up to 540,000 flights a year before the new runway is built.
And the consultation proposes changes to the agreements which govern the direction in which aircraft leave and arrive at the airport, but maintains the 127 sq km limit on the area "significantly affected" by aircraft noise - at levels of 57 decibels.
'Running scared'
The government says it would have to be confident that any expansion would be able to comply with EU limits on air pollution, due to come into force from 2010.
Ms Kelly said: "Heathrow supports 170,000 jobs, billions of pounds of British exports and is our main gateway to the global economy. But for too long it has operated at nearly full capacity, with relatively minor problems causing severe delays to passengers.
"If nothing changes, Heathrow's status as a world-class airport will be gradually eroded - jobs will be lost and the economy will suffer."
But the Conservatives accused Ms Kelly of "running scared" as she issued a written statement, rather than coming to Parliament to answer MPs' questions.
Shadow transport secretary Theresa Villiers said there were "tough questions" to answer as Prime Minister Gordon Brown had said he would look at whether carbon emissions could be cut by 80%.
She said: "This is one of the most important decisions we face as a nation and it is scandalous that Ruth Kelly won't answer in Parliament to the MPs who represent people whose lives are directly impacted by the future Heathrow."
'Over capacity'
The announcement follows consultation on plans to expand Heathrow, which were first mooted in the government's 2003 aviation White Paper.
BAA chief executive Stephen Nelson told BBC Radio 4's Today programme: "It's been over capacity for 17 years, it's now handling 60,000 more passengers a day than it was built for - that puts us under extraordinary pressure."
He said the airport was an "economic powerhouse" which brought tourists, businesses and jobs to London - he argues a third runway could be worth £9bn a year to the national economy.
 A report gave Heathrow a low satisfaction rating for crowding |
But John Stewart, chairman of the anti-airport expansion group Hacan, questioned the figures, telling the BBC: "There's a mantra here that it's important for the economy - the expansion of Heathrow. What has never been worked out is how those figures are arrived at."
He said instead of further expansion, short haul flights to destinations with good rail services, like Paris, should be regulated to allow more long-haul flights to India and China to come in for business reasons.
'Robbed of peace'
And he said the proposals could be defeated by the strength of opposition to them from local authorities, MPs and "direct action activists".
The 2M Group, which represents 12 local authorities in the Heathrow area, says the plans will mean increased noise for more than 50 towns and communities.
It said the expansion would mean 900 extra flights a day and noise affecting residents living as far west from the airport as Maidenhead and Windsor and into Kensington and Chelsea in London.
Susan Kramer, the Lib Dems' transport spokeswoman, whose Richmond Park constituency is among those affected, said the plans would rob people in west London of the "half day of peace" they currently get.
She added: "At a time of climate change, with aviation having such a big impact, shouldn't we be completely rethinking this and putting that kind of investment into rail?"
"Why on earth should people not have fast trains to get around the UK or to nearby places on the continent, then any need for expansion would disappear."
Worn out
Greenpeace executive director John Sauven said the aviation industry "pulls figures out of the air", adding: "They want the country to believe that our national economic well-being relies on a mile-long strip of tarmac covering a local village in west London.
"In reality, UK residents spend far more money abroad than visitors spend here, costing the country billions, and that figure is growing, due in part to airport expansion."
But the GMB union said an extra runway and terminal at Heathrow would be welcome because the current infrastructure was worn out and a major cause of delays to flights.
And David Frost, director general of the British Chambers of Commerce, said: "Our economy is being restricted by transport infrastructure that is falling short of both expectations and requirements.
"Heathrow expansion is one of the fundamental infrastructure projects necessary to keep the country competitive. Continental airports have far larger capacities and the UK is in danger of losing out on being a major hub for international flights."
PROJECTED NOISE FOOTPRINTS FOR HEATHROW EXPANSION  2002 Recent noise footprint showing sound at 57 decibels - the point at which the government says noise becomes "a community annoyance". There were 466,000 Air Transport Movements (ATMs) in 2002; defined as a plane taking off or landing. 2015 Indicative noise contour if planes were taking off and landing on both of Heathrow's runways. 540,000 ATMs a year. 2020 A projection showing three runways in action with 702,000 ATMs a year. Source: Department for Transport |
