Quota Count is a system used in the UK by London's

Heathrow Heathrow Airport (), called ''London Airport'' until 1966 and now known as London Heathrow , is a major international airport in London, England. It is the largest of the six international airports in the London airport system (the others bei ...

Gatwick Gatwick Airport (), also known as London Gatwick , is a major international airport near Crawley, West Sussex, England, south of Central London. In 2021, Gatwick was the third-busiest airport by total passenger traffic in the UK, after H ...

, and

Stansted London Stansted Airport is a tertiary international airport serving London, England, United Kingdom. It is located near Stansted Mountfitchet, Essex, England, northeast of Central London. London Stansted serves over 160 destinations acro ...

airports to limit the amount of

noise Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arise ...

generated by aircraft movements at night time (23:30–06:00).

Description

From 1962 until 1993, operations at Heathrow were subject to a simple limit on the number of aircraft movements that were allowed to take place during the night period. In 1993 a new Quota Count system was introduced based on aircraft noise certification data. Each aircraft type is classified and awarded a quota count (QC) value depending on the amount of noise it generated under controlled certification conditions. The quieter the aircraft the smaller the QC value. Aircraft are classified separately for landing and take-off. Take-off quota count values are based on the average of the certificated flyover and sideline noise levels at maximum take-off weight, with 1.75EPNdB added for Chapter 2 aircraft. Landing quota count values are based on the certificated approach noise level at maximum landing weight minus 9.0EPNdB. Aircraft were originally divided into six QC bands from 0.5 to 16, but following a review by the

Department for Transport The Department for Transport (DfT) is a department of His Majesty's Government responsible for the English transport network and a limited number of transport matters in Scotland, Wales and Northern Ireland that have not been devolved. The d ...

a seventh category – Quota Count 0.25 – was added in March 2007 and an eighth category – Quota Count 0.125 – in September 2018. The quota count doubles with each increase of 3 dB which corresponds to an approximate doubling of noise power. However, due to the

logarithm In mathematics, the logarithm is the inverse function to exponentiation. That means the logarithm of a number to the base is the exponent to which must be raised, to produce . For example, since , the ''logarithm base'' 10 o ...

ic nature of human aural perception, this 3 dB change is perceived as only a small change in the noise level. Airports operating the system have a fixed quota for each of the summer and winter seasons. As each night-time aircraft movement takes place, an amount of this quota is used depending on the classification of the aircraft. For example, the

Boeing 747-400 The Boeing 747-400 is a large, long-range wide-body airliner produced by Boeing Commercial Airplanes, an advanced variant of the initial Boeing 747. The "Advanced Series 300" was announced at the September 1984 Farnborough Airshow, targeting ...

is classed as QC/2 on landing and QC/4 on takeoff, while the larger yet quieter

Airbus A380 The Airbus A380 is a large wide-body airliner that was developed and produced by Airbus. It is the world's largest passenger airliner and only full-length double-deck jet airliner. Airbus studies started in 1988, and the project was annou ...

is rated QC/0.5 on landing and QC/2 on takeoff. Each A380 therefore uses approximately 42% of the quota of a 747, while potentially carrying more passengers, thus providing airlines with an incentive to operate quieter types of aircraft. Field measurements suggest the approach quota allocation for the A380 may be overly generous compared to the older Boeing 747. Rolls-Royce is supporting CAA in understanding the relatively high A380/Trent 900 monitored noise levels.https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/66837/consultation-document.pdf

Some QC examples

Subject to some limited carry-over provisions, when the airport's quota has been fully used up, no more night-time movements are allowed to take place. In practice, the airport spreads the quota so that it is used evenly across the season. The quotas allocated to each airport operating the system are gradually reduced year-on-year in order to achieve long-term reductions in the impact of night-time aircraft noise. (e.g

!--http://www.gatwickairport.com/noise/definition/around-airport/night/ does about future-->)

London Heathrow Airport Heathrow Airport (), called ''London Airport'' until 1966 and now known as London Heathrow , is a major international airport in London, England. It is the largest of the six international airports in the Airports of London, London airport sys ...

prohibits aircraft noisier than QC/2 to operate at night. As this is more stringent than the

ICAO The International Civil Aviation Organization (ICAO, ) is a specialized agency of the United Nations that coordinates the principles and techniques of international air navigation, and fosters the planning and development of international a ...

's Chapter 4 limits, QC/2 has become a

de facto ''De facto'' ( ; , "in fact") describes practices that exist in reality, whether or not they are officially recognized by laws or other formal norms. It is commonly used to refer to what happens in practice, in contrast with ''de jure'' ("by la ...

aircraft noise standard. The Quota Count system has been adapted for use in

Madrid Madrid ( , ) is the capital and most populous city of Spain. The city has almost 3.4 million inhabitants and a metropolitan area population of approximately 6.7 million. It is the second-largest city in the European Union (EU), and ...

Brussels Brussels (french: Bruxelles or ; nl, Brussel ), officially the Brussels-Capital Region (All text and all but one graphic show the English name as Brussels-Capital Region.) (french: link=no, Région de Bruxelles-Capitale; nl, link=no, Bruss ...

and Aberdeen.

Notes and references

External links

London Heathrow, London Gatwick and London Stansted Airports Noise Restrictions Notice 2014
{dead link, date=November 2015 Environmental law Heathrow Airport Night flying Noise pollution Quotas