Under the flight path… reducing noise


By Heathrow

Published 3rd April 2014

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Here at yourHeathrow we’re dissecting the noise debate with a look at the issues, under the flight path, and what Heathrow is doing to reduce the impact of noise.

A noisy issue…

It’s important to acknowledge the impact aircraft noise has on the surrounding community and how noise effects people differently. While the health impacts of noise are unclear, we know noise can cause distraction, sleep disturbance, speech interference and general annoyance for residents.

The direction that aircraft fly at Heathrow depends on the wind direction, as aircraft must take-off and land into the wind. Wind direction around London is mainly from the west. Most aircraft arrive over London from the east and take off towards the west; we call this westerly operations which occurs on average 70% of the year. During easterly operations, aircraft will arrive from the west over Windsor and this occurs on the remaining 30% of the year (see also – Wind Direction…how and why it affects Heathrow operations).

Aircraft coming into land at Heathrow use what is known as the Instrument Landing System or ILS. The ILS is a beam that is aligned with the runway centreline to guide aircraft in a straight line approach to the runway for landing. Any area beneath the ILS will be overflown by arriving aircraft. Additionally any areas to the sides of the ILS can be overflown by aircraft being directed to the ILS. Aircraft arriving at Heathrow airport join the ILS from both the north and south.

Heathrow is currently in the process of replacing each of the ILS antennae at the end of each runway with more advanced technology to allow for more flight movements during low visibility (more information is available here).

The number of flights using Heathrow has not changed significantly for over 10 years. During busy periods, arriving aircraft perform a fixed circling pattern known as stacks while waiting to land at Heathrow. All airports have a number of stacks of which Heathrow has four: Bovingdon; Lambourne; Ockham and Biggin. The stacks have been in the same location since the 1960s, which is set by Government policy. Unlike departing aircraft that have fixed directions, there are no set routes for aircraft moving from the holding stacks to the final approach (landing) and this is why residents hear aircraft on some days and not others.

Want to see where aircraft are flying in relation to where you live or work? Check out our online tracking tool.

Turning down the volume on noise

Despite double the number of aircraft since 1974, the noise level has actually reduced for residents living under Heathrow’s flight paths. With some of the toughest noise restrictions in the world, noise is at the forefront of Heathrow’s agenda with a number of approaches taken to make operations quieter.

Airlines are incentivised to use quieter aircraft through the imposition of fines for noisy aircraft and reduced charges for quieter aircraft. Later in the year we’ll be taking this one step further by ranking airlines noise performance.

In order to provide relief from noise for residents living under the path into Heathrow, we operate a runway alternation programme when we are on westerly operations. This means one runway is used by landing aircraft between certain timeframes and halfway through the day arrivals then switch to the other runway until the last departure. The pattern alternates on a weekly basis with flights landing on the southern runway in the morning and the northern runway in the afternoon and vice versa.

An arrivals procedure known as ‘Continuous Descent Approaches’ has been in operation at Heathrow for many years. This procedure involves aircraft maintaining a steady angle of approach when landing at the airport, as opposed to approaches which involve prolonged periods of level flight. The intention of a CDA is to keep aircraft higher for longer, thereby reducing arrival noise.

Additionally, we’ve also launched the Fly Quiet Programme which records and ranks airlines against each other in terms of sustainability measures, including noise.

Heathrow also provides noise insulation for homes (40,000 in total) and schools around the airport and offers financial assistance for the relocation to quieter areas.

There’s also more information available on the Heathrow noise website – www.heathrow.com/noise.


By Heathrow

Published 3rd April 2014