• To see a larger version of the flight paths click here and scroll down.

Noise created by a third runway at Heathrow would have a "serious impact" on Merton residents, councillors have said.

Maps published on Monday by a group of local authorities including Merton reveal how new flight paths could affect much of the capital.

The maps show some aircraft taking off from Heathrow would fly over Wimbledon and pass close to Mitcham, while another proposed flight path for planes landing at the airport would also cross over Mitcham.

Merton Council is one of 12 local authorities in the 2M Group, which has called on the Government to rethink its plans.

Councillor Tariq Ahmad, cabinet member for the environment, said: "There's always a tendency for us to think we don't need to worry about flight paths in this borough, but the new runway will have a serious impact. There will be an environmental impact, and most certainly a change in noise pollution, not just for us but across London as a whole."

These plans are a separate issue from night flights and only include flights taking off and landing from 6am until 11pm.

Plans for a third runway could be approved by the Government in April and the new runway could open in 2015. But ministers are also expected to pave the way for increased Heathrow traffic by ending runway alternation.

This currently gives communities some peace by switching the runway in operation at 3pm every day. Under the new proposals, aircraft would take off and land from the two runways in parallel.

Wandsworth Council leader Edward Lister said: "The loss of runway alternation would be felt particularly keenly in south and west London.

"At least under the current system you know you will get a break from the noise. If the Government gets its way there will be no respite during the day."

But a spokeswoman for Heathrow said the maps were simply speculating about possible flight paths and that concerns over the environment and noise would be considered by the Government during consultation over Heathrow's expansion.

She added that the changes were necessary: "Heathrow's terminals are overcrowded and its two runways are full, operating at 98.5 per cent of their permitted capacity. Heathrow is vital to the health of the British economy but we believe its expansion should only take place if the impacts can be mitigated and tough environmental standards can be met."

If runway alternation is ended, the number of annual flights taking off and landing at Heathrow could rise by 35,000 to 515,000 a year.

If a third runway is also built, the number of flights each year at Heathrow would increase to more than 700,000.

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