science

Quota Count system

Quota Count system is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Quota Count system rather than just read about it. In short: Quota Count is a system used in the UK by London's Heathrow, Gatwick, Stansted and Birmingham airports to limit the amount of noise 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.

Key takeaways

Quota Count system belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Quota Count system to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Quota Count system from memory before moving on to harder problems.

Reference excerpt

Quota Count is a system used in the UK by London's Heathrow, Gatwick, Stansted and Birmingham airports to limit the amount of noise 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 1.75 EPNdB added for Chapter 2 aircraft. Landing quota count values are based on the certificated approach noise level at maximum landing weight minus 9.0 EPNdB. Aircraft were originally divided into six QC bands from 0.5 to 16, but following a review by the Department for Transport 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 logarithmic 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 is classed as QC/2 on landing and QC/4 on takeoff, while the larger yet quieter Airbus A380 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.

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 reduced periodically in order to achieve long-term reductions in the impact of night-time aircraft noise, the last such reduction having been in the Summer 2019 season. London Heathrow Airport prohibits aircraft noisier than QC/2 to operate at night. As this is more stringent than the ICAO's Chapter 4 limits, QC/2 has become a de facto aircraft noise standard. The Quota Count system has been adapted for use in Madrid, Brussels and Aberdeen.

Notes and references

External links London Heathrow, London Gatwick and London Stansted Airports Noise Restrictions Notice 2014

Worked examples

Example 1 — a first encounter with Quota Count system

Start with the simplest possible case. Write down what Quota Count system claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Quota Count system before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Quota Count system ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Quota Count system

In research: Quota Count system appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Quota Count system in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Quota Count system is common in secondary-school and first-year university syllabi. It links to neighbouring topics Environmental law, Heathrow Airport, Night flying, so understanding it makes those chapters shorter.
In everyday life: Look for Quota Count system outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Quota Count system in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Quota Count system means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Quota Count system out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Quota Count system in simple terms?

Quota Count is a system used in the UK by London's Heathrow, Gatwick, Stansted and Birmingham airports to limit the amount of noise 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 a…

Why does Quota Count system matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Quota Count system?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Quota Count system.