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Noise FAQs

Below are answers to some of the most frequently asked questions we receive. They cover the main areas of night flights and early morning arrivals; flight numbers; Heathrow’s flight paths.  If you have questions that are not answered here, please give us a call on 0800 344 844.

We publish a range of data on a daily basis – this includes information on the total number of flights using Heathrow; a breakdown of the number of flights between 23:00-06:00; the direction of operation (westerly/easterly); total flights out of alternation and the number of complaints received.  The information can be found at www.heathrowoperationaldata.com


How does the wind direction change how I am affected  by noise from aircraft using Heathrow?

Heathrow has two runways – the northern and southern. The direction that aircraft fly at Heathrow depends on the wind direction – this is because aircraft have to take-off and land into the wind.   The prevailing wind direction around London is from the west. Because aircraft must land into the wind, the majority of aircraft arrive from the east (over London) and take off towards the west (over Berkshire/Surrey).  We call this westerly operations.  

When the wind is coming from the east, aircraft will arrive from the west (over Windsor) and depart towards London.  This is called easterly operations.  

The direction of the wind is assessed at the airport at ground level and at 1,000ft and 2,000ft by Air Traffic Control (ATC) and also with reference to reports from aircrew. It is important to note that the wind on the ground at the airfield can vary from that even locally.

On average, the airport is on westerly operations for 70% of the year and easterly operations for the remaining 30% of the year.  The percentage of westerlies and easterlies varies from week to week and month to month.    

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What is runway alternation?

In order to provide relief from noise for residents living under the final approach 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 06:00-15:00.  Arrivals then switch to the other runway from 15:00 to the last departure.  The pattern alternates on a weekly basis.  

So for example one week, flights will land on the southern runway in the morning and the northern runway in the afternoon.  The following week flights will land on the northern runway in the morning and the southern runway in the afternoon.  There is also a runway alternation pattern for flights during the night.

The runway alternation pattern only applies when we are on westerly operations.  We don’t currently alternate the runways when we are on easterly operations although we hope to introduce this in late 2014, once the necessary taxiway works have been undertaken at the airport.  Some of the works required will be subject to a planning application in 2013.

We publish an annual alternation schedule in the ‘What we do about it’ section on this website.

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I live under one of the final approach paths into Heathrow and occasionally notice aircraft landing out of the published alternation pattern.  Why is this?

Whilst every effort is made to adhere to the alternation programme, there are occasions when circumstances mean that changes need to be made at short notice. For example, occasionally for safety reasons it is necessary for aircraft to land on the runway not scheduled for landings. Additionally, if there is a build-up of traffic in the holding stacks, or within UK and neighbouring airspace, air traffic controllers may need to use both runways for arrivals for a short period. This is known as Tactically Enhanced Arrivals Mode (TEAM).  

Because of the large number of arriving flights at the beginning of the day, both runways are used most days for landings between 6-7am.   

The percentage of aircraft that stick to the published alternation schedule is reported to the independent committee, the Heathrow Airport Consultative Committee (www.hacc.org.uk).  We also report this in the Flight Performance quarterly reports published in the reports section on this website.

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I live under one of the holding stacks/path from stacks – how am I affected by aircraft noise?

During busy periods, aircraft will circle in the holding stacks waiting to land at Heathrow.  There are no set routes from the holding stacks to the final approach paths into Heathrow and therefore the number of aircraft you hear will vary from day to day.

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Flights appear to be flying lower – why is this?

Arriving aircraft at Heathrow have no set routes or heights, unlike departing aircraft.  However, heights have remained pretty constant since aircraft cannot lose too much altitude as they need to be at a certain height when they join the final approach into Heathrow.

Aircraft coming into land at Heathrow use what is known as the Instrument Landing System or ILS.  The ILS is a beam which is aligned with the runway centreline in order to guide aircraft in a straight line approach to the runway threshold for landing.

The angle at which aircraft land is set at 3°, which is the angle recommended by the International Civil Aviation Organisation (ICAO). As a result of the set 3° approach angle, aircraft using the ILS will be at a set height for distance from the runway. Aircraft joining the ILS at Heathrow will be within a couple of hundred feet.  This has not changed.

In addition, there are rules laid down in the Airport’s AIP (Aeronautical Information Publication)  which states that the minimum height at which aircraft can join the ILS during the day (between 7am and 11pm) is 2,500ft at 7.5 nautical miles from Heathrow. At night they must be no lower than 3,000ft at 10 nautical miles from Heathrow.  

The Joining Point data is collected and monitored daily and any trends in terms of aircraft joining lower are highlighted to air traffic provider, NATS and investigated.  There have been no fluctuations recently. Adherence to the Joining Point Rules is reported quarterly in our Flight Performance reports.

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Who sets departure routes at Heathrow?

At Heathrow there are approximately 650 departures every day. Most of these happen between 06:00 and 23:00 hours local every night.

All aircraft leaving Heathrow Airport should follow flight paths known as Noise Preferential Routes (NPRs) up to an altitude of 4000ft. NPRs were set by the Department for Transport (DfT) in the 1960s and were designed to avoid overflight of built-up areas where possible, these have not changed since.

If you live near or beneath a departure route you will see aircraft taking off and may hear noise when that route is being used. How often any particular route is used will vary, and is an operational decision for ATC. They have to take account of the final destination of each flight and factors such as the overall air traffic and weather conditions, both locally and along intended routes. There are no requirements in terms of the number of aircraft which may be directed down each departure route.

Track keeping at Heathrow is very good. In 2012 over 93% of all departures from Heathrow were on-track. Any flight leaving a departure route below 4,000ft (called a track deviation) is automatically tagged by the Noise and Track Keeping System at Heathrow. Details of all track deviations are analysed to check the reasons for this.

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I am disturbed by arriving aircraft flying very early in the morning. I thought there was a ban on flights at night?

There is not a ban on flights at night however Heathrow is heavily restricted by the Government in terms of the numbers and types of aircraft that are allowed to operate between 23:00 and 06:00.

Generally speaking the majority of flights during the night time period are early morning arrivals.  On average there are 14-16 arrivals between 04:30 - 06:00. The first scheduled arrival is 04:50 although aircraft can and do sometimes arrive earlier for example aircraft flying into the UK from North America, frequently encounter tail winds that make their time of arrival unpredictable. All the flights arriving before 06:00 count towards the night flights movement and quota limits set by the Government.

To address residents’ concerns, the Government consults on night flights every five years and determines how many aircraft are allowed between 11.30pm and 6am at Heathrow, Gatwick and Stansted. It also determines how quiet these aircraft need to be. At Heathrow, the current limits allow 5800 movements per year. These are consulted on and set every 5 years.  

In November 2013, the Government announced a second consultation on night flights at Heathrow, Gatwick and Stansted which sets out the Government’s proposals for the next regime.  Robert Goodwill made a written statement about this and the full details and the results of the first consultation have been published at https://www.gov.uk/government/consultations/night-flights

The Government are proposing to set a three year regime which lasts until October 2017, retaining the main features of the current regime, as they do not think it is sensible to make any significant changes to the current regime until the Airports Commission reports in 2015.  
The consultation will run until 31st January 2014 and DfT will announce their decisions for the next regime by Spring 2014.   

To tackle late-running departures, we are focused on working with our airline customers and air traffic control to reduce delays at the airport and to reduce the numbers of aircraft that leave late at the end of the day.

We are seeking a voluntary ban of the noisiest aircraft operating at Heathrow (known as Marginally Compliant Aircraft). Working with the airlines our ambition is to stop the operation of these by 2015.

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Why do I sometimes get disturbed by flights after 23:00?

There are no scheduled flight departures between 23:00 and 06:00.  However, aircraft sometimes operate after 23:00 due to delays that may be caused by bad weather, for example snow, or technical problems or they may be small  quieter aircraft which are exempt from the restrictions.

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Did you know…

…we charge more for noisier planes to land?

Heathrow’s landing charges vary according to how noisy aircraft are.  This is to encourage airlines to use their quietest fleets.  For example, the noisiest types of aircraft operating at Heathrow pay four times more than the quietest aircraft.  This charging structure has influenced the airlines choice of aircraft fleet used at Heathrow over the years.

…we fine airlines that break the noise limits on departure?

There are set noise limits for aircraft departing from Heathrow. The Government set these limits.  Departures are continually monitored and if an aircraft creates more noise than is allowed, the airline is fined up to £1,000. This money is distributed to a range of local community projects.  If you would like to find out more about the grants available, see  www.heathrowairport.com/communitymatters.

Still got questions? There’s lots more information on our website www.heathrowairport.com/noise.

Alternatively please call us on Freephone 0800 344844 during office hours or email noise_complaints@heathrow.com

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