Using the Mayor of London’s preferred 55 dB Lden measure for noise around 200,000 people, and potentially as many as 325,950 will be taken out of Heathrow’s noise footprint, according to the CAA forecast.
The airport claims that the data confirms that between 34,450 and 49,550 fewer people could be affected by aircraft noise with a third runway in 2040 than today, based on the government’s preferred 57dB LAeq measure of noise.
A combination of a new runway location, steeper landing approaches and new aircraft technology make the noise decline possible, says the airport.
The data forms part of a series of technical annexes that Heathrow is submitting to the Airports Commission and publishing on its website today.
The technical submission on noise provides indicative flight path maps which Heathrow alleges confirm that a reduction in noise and periods of noise respite for local communities are achievable with a third runway.
The flight paths show that by 2040 there will be at least 15% fewer people exposed to 57dB LAeq compared with today.
According to the gateway, using 55dB Lden measure, the London Mayor’s preferred approach, shows at least a 28% reduction in population exposed to noise.
It points out that it is not proposing any extra night flights and the plans could reduce the number of night flights on existing flight paths.
Indeed, it says that residents under existing flight paths could have night flights only every third week rather than every other week today.
It notes that the indicative flight paths detailed in the document show that Heathrow would be able to provide periods of respite from noise for all local communities with a third runway.
Heathrow insists that the public consultation that it held at the start of 2014 showed a strong preference from local communities for runway alternation and noise respite to be maintained.
A further consultation on proposed noise mitigation and compensation for local communities will be launched in a few weeks’ time.
Matt Gorman, Heathrow's sustainability sirector said: “The CAA’s modelling shows that Heathrow can reduce aircraft noise while delivering the long-haul flights that Britain needs to prosper in a global economy.
“As we have seen recently with the significant opposition to the changes to flight paths at Gatwick, any decision on the location of new flight paths will be difficult. While some people could experience more noise, others who are under existing flight paths in places like Richmond could experience less noise than today.
"The flight paths that we are publishing are indicative only and will be the subject of extensive debate and consultation if government approves a third runway.”