People living in Hounslow, Heston, Isleworth and parts of Brentford would all be subjected to up to 13 hours of aircraft noise a day if a third runway is built at Heathrow, it is claimed.
Anti-Heathrow expansion campaign group HACAN says it has unearthed information 'buried' in a report by the airport which shows the true impact of a new landing strip on those living under the flight paths.
Heathrow has denied HACAN's claims and said it would work with residents to ensure long periods of respite could be maintained with a new runway.
HACAN says households within five miles of the proposed new runway, including those in Heston and Brentford, would have to endure a jet passing overhead every 90 seconds for between 12 and 13 hours a day.
People living under the southern flight path would face a similar burden, with their guaranteed half-day respite from noise being slashed by four hours under the plans, the group says.
Although those living under the flight path for the existing northern runway would retain their eight hours of peace, HACAN says the new landing strip to the north west would be so close they would also be affected by the noise from planes landing there.
HACAN chairman John Stewart said: "The prospect of 13-hour flying is nightmarish. Quite simply, many communities are going to be hammered if a third runway is built.
"Heathrow Airport hasn't hidden the information but the fact that it is buried in an appendix shows how reluctant they are to spell out the implications of a new runway."
At the moment, one runway is used for landings and one for take-offs, with the roles switching at 3pm each day to ensure guaranteed periods of peace for Heathrow's neighbours.
Heathrow has assured residents under existing flight paths and those who would be affected by a new runway that they would continue to enjoy some respite from the noise.
But HACAN says the 'buried' information, contained in an appendix to a report Heathrow submitted to the Airports Commission, shows this will be considerably less than at present.
The Airports Commission , chaired by Sir Howard Davies, was set up by the Government to examine the need for increased aviation capacity in the UK.
It is due to make its recommendations on proposals including a third runway at Heathrow and a second at Gatwick next summer.
A Heathrow spokeswoman said: "It is wrong to suggest most residents would be subject to 13 hours of aircraft noise with a third runway.
"We submitted a number of options to the Airports Commission, one of which we identified as having clear advantages because of its ability to maintain long periods of respite, whilst reducing the total number of people exposed to noise compared to today.
"We understand that respite is important to residents and if a third runway is recommended, we plan to consult further with local communities on how it will be delivered."
How would you be affected by a third runway, according to HACAN?
Homes under the flight path of the southern runway, including those in Hounslow, Isleworth and Richmond
Planes landing for 12-13 hours a day
Homes under the flight path of the existing northern runway, including those in Cranford, Heston and Osterley
Planes landing for six to seven hours a day, but jets using the new runway would also be audible
Homes under the flight path of the proposed third runway to the north-west of the existing two, including Heston and Brentford
Planes landing for 12-13 hours a day
