Editing Heathrow Airport (section)

===Flight movements===
Aircraft destined for Heathrow are usually routed to one of [[Heathrow arrival stacks|four holding points]]. [[Air traffic controller]]s at Heathrow Approach Control (based in [[Swanwick, Hampshire]]) then guide the aircraft to their final approach, merging aircraft from the four holds into a single stream of traffic, sometimes as close as {{convert|2.5|NM}} apart. Considerable use is made of [[continuous descent approach]] techniques to minimise the environmental effects of incoming aircraft, particularly at night.<ref name="Heathrow2004">{{cite report|publisher=BAA Heathrow|title=Flight Evaluation Report 2004/05|date=2004–2005|url=http://www.heathrowairport.com/assets//B2CPortal/Static%20Files/New2005Booklet.pdf|access-date=2 November 2007|archive-url=https://web.archive.org/web/20051126064156/http://www.heathrowairport.com/assets//B2CPortal/Static%20Files/New2005Booklet.pdf|archive-date=26 November 2005|url-status=dead}}</ref> Once an aircraft is established on its final approach, control is handed over to Heathrow Tower.

When runway alternation was introduced, aircraft generated significantly more noise on departure than when landing, so a preference for westerly operations during daylight was introduced, which continues to this day.<ref name="Ref_o">During periods of westerly operation, aircraft continue to fly in a westerly direction with an easterly tailwind component of up to {{convert|5|kn|km/h mph}}, if the runway is dry and there is no significant crosswind.</ref> In this mode, aircraft take off towards the west and land from the east over London, thereby minimising the impact of noise on the most densely populated areas. Heathrow's two runways generally operate in segregated mode, whereby landings are allocated to one runway and takeoffs to the other. To further reduce noise nuisance, the use of runways 27R and 27L is swapped at 15:00 each day if the wind is from the west. When landings are easterly there is no alternation; 09L remains the landing runway and 09R the takeoff runway due to the legacy of the now rescinded [[Cranford Agreement]], pending taxiway works to allow the roles to be reversed. Occasionally, landings are allowed on the nominated departure runway, to help reduce airborne delays and to position landing aircraft closer to their terminal, reducing taxi times.

Night-time flights at Heathrow are subject to [[Night flying restrictions|restrictions]]. Between 23:00 and 04:00, the noisiest aircraft (rated [[Quota Count system|QC]]/8 and QC/16) cannot be scheduled for operation. Also, during the night quota period (23:30–06:00) there are four limits:
* A limit on the number of flights allowed.
* A [[Quota Count system]] which limits the total amount of noise permitted, but allows operators to choose to operate fewer noisy aircraft or a greater number of quieter planes.<ref name="Ref_p">{{cite web|title=Noise limits|url=http://www.heathrowairport.com/noise/what-we-do-about-it/measures-already-in-place/noise-limits|publisher=Heathrow Airport|access-date=27 January 2013|archive-url=https://web.archive.org/web/20121225040213/http://www.heathrowairport.com/noise/what-we-do-about-it/measures-already-in-place/noise-limits|archive-date=25 December 2012|url-status=live}}</ref>
* QC/4 aircraft cannot be scheduled for operation.
* A voluntary agreement with the airlines that no early-morning arrivals will be scheduled to land before 04:30.

A trial of "noise-relief zones" ran from December 2012 to March 2013, which concentrated approach flight paths into defined areas compared with the existing paths which were spread out. The zones used alternated weekly, meaning residents in the "no-fly" areas received respite from aircraft noise for set periods.<ref>{{cite news|title=Heathrow begins trial of noise relief zones|url=https://www.bbc.co.uk/news/uk-england-london-20591037|work=BBC News|date=4 December 2012|access-date=23 March 2018|archive-url=https://web.archive.org/web/20181118151208/https://www.bbc.co.uk/news/uk-england-london-20591037|archive-date=18 November 2018|url-status=live}}</ref> However, it was concluded that some residents in other areas experienced more noise as a consequence of the trial and that it should therefore not be taken forward in its current form. Heathrow received more than 25,000 noise complaints in just three months over the summer of 2016, but around half were made by the same ten people.<ref>{{cite news|url=https://www.telegraph.co.uk/travel/news/half-of-heathrow-noise-complaints-made-by-just-10-people/|title=Half of Heathrow's 25,000 noise complaints made by the same 10 people|date=1 November 2016|access-date=23 March 2018|work=The Telegraph|author=Hugh Morris|archive-url=https://web.archive.org/web/20180324162311/https://www.telegraph.co.uk/travel/news/half-of-heathrow-noise-complaints-made-by-just-10-people/|archive-date=24 March 2018|url-status=live}}</ref>

In 2017, Heathrow introduced "Fly Quiet & Green", a quarterly published league table (suspended in 2020 due to the Covid pandemic) that awards points to the 50 busiest airlines at the airport, ostensibly based on their performance relative to each other across a range of seven environmental benchmarks, such as {{NOx}} emissions.<ref>{{cite web|url=https://www.heathrowflyquieterandgreener.com/|title=Heathrow Fly Quiet and Green|publisher=Heathrow Airport|access-date=28 October 2021|archive-date=19 November 2024|archive-url=https://web.archive.org/web/20241119210735/https://heathrowflyquieterandgreener.com/|url-status=live}}</ref> Heathrow has acknowledged, but not attempted to refute, criticism over discrepancies and a lack of transparency over the way in which the figures are calculated.<ref>{{cite web|url=https://www.heathrow.com/content/dam/heathrow/web/common/documents/company/local-community/noise/making-heathrow-quiter/noise-action-plan/Noise_Action_Plan_2019-2023_Supporting_Annexes.pdf|title=Heathrow Noise Action Plan 2019–2023 Supporting Annexes|publisher=Heathrow Airport|access-date=28 October 2021|archive-date=28 October 2021|archive-url=https://web.archive.org/web/20211028102456/https://www.heathrow.com/content/dam/heathrow/web/common/documents/company/local-community/noise/making-heathrow-quiter/noise-action-plan/Noise_Action_Plan_2019-2023_Supporting_Annexes.pdf|url-status=live}}</ref> The airport has always refused to publish a breakdown showing how many "Fly Quiet points" each performance benchmark has contributed towards the total score it awards to an airline, thereby putting obstacles in the way of any independent auditing of the published results.<ref>{{cite web|url=https://www.airportwatch.org.uk/wp-content/uploads/2019/03/Fly-Quiet-Green-Forensics-V1.3.pdf|title=Fly Quiet & Green Forensics|publisher=AirportWatch|author=AvGen Ltd|date=March 2019|access-date=6 November 2021|archive-date=6 November 2021|archive-url=https://web.archive.org/web/20211106083121/https://www.airportwatch.org.uk/wp-content/uploads/2019/03/Fly-Quiet-Green-Forensics-V1.3.pdf|url-status=live}}</ref> Among other criticisms of the league table are the unexplained omission of some of the poorer performers among the 50 busiest airlines<ref>{{cite web|url=https://www.heathrowflyquieterandgreener.com/q2-2019/|title=Q2 2019 Fly Quiet 'Top 50' Airlines, wrongly omitting Korean Air|date=20 August 2019|publisher=Heathrow Airport|access-date=21 December 2021|archive-url=https://web.archive.org/web/20200123094959/https://www.heathrowflyquietandgreen.com/q2-2019/|archive-date=23 January 2020}}</ref> and the emphasis on relative rather than absolute performance,<ref>{{cite web|url=https://www.heathrowflyquieterandgreener.com/how-we-calculate/|title = Heathrow Fly Quiet and Green – How We Calculate|date = 10 May 2016|publisher=Heathrow Airport|access-date=28 October 2021}}</ref> so an airline could well improve its "Fly Quiet" score quarter-on-quarter even if its environmental performance had in fact worsened over the period. In October 2024, Heathrow finally reinstated the programme, rebadged as “Fly Quieter & Greener”. Two more environmental benchmarks were added to the previous seven, but in all other respects the aforementioned deficiencies of the original scheme remain.<ref>{{cite web|url=https://mediacentre.heathrow.com/pressrelease/detail/21065/|title=Heathrow relaunches airlines' sustainability performance league table|date=22 October 2024|publisher=Heathrow Airport|access-date=2 November 2024|archive-date=15 December 2024|archive-url=https://web.archive.org/web/20241215165017/https://mediacentre.heathrow.com/pressrelease/detail/21065/|url-status=live}}</ref>

Due to the [[COVID-19 pandemic]] Heathrow has seen a large increase in cargo-only flights, not only by already established carriers at the airport operating cargo-only flights using passenger aircraft but also by several cargo-only airlines.<ref>[https://www.heathrow.com/latest-news/heathrow-equips-uk-data-revealed – Heathrow News] retrieved 20 January 2021</ref>