Aviation contributes to global warming mainly through the release of carbon dioxide (CO₂) when burning jet fuel. It also produces other gases and particles at high altitudes, which can have additional warming effects. The Climate Change Committee's 7th Carbon Budget report warns that, as other sectors decarbonise, aviation’s share of emissions is expected to grow unless new technologies and fuels are adopted. The UK Government has set a legally binding target to reach net zero by 2050. The CAA supports this goal by regulating safely the introduction of new aircraft designs and fuels, providing impartial data, and advising on policies that can deliver meaningful reductions in emissions.
Aviation is one of the hardest sectors to decarbonise, but every efficiency gained – whether from cleaner fuels, smarter flight paths, or better technology – reduces emissions and helps the UK meet its climate commitments. The aviation industry is exploring different ways to reduce emissions from aircraft through more efficient operations to reduce the amount of fuel they use and through the development of new fuel technologies. Some of these, such as Sustainable Aviation Fuels (SAF), are available now and are already in use. Others, such as hydrogen or electric powered aircraft are still in development, and it will be several years before they can be used for commercial flights.
We work with government and industry to cut aviation’s carbon footprint, helping to ensure that growth in air travel is compatible with the UK’s net zero goals. Our role includes:
- Co-leading, with the Department for Transport, the modernisation of the UK’s airspace;
- Responsibility for deciding whether to approve an airspace change proposal to the notified airspace design for which the UK is responsible.
- Setting and enforcing standards so that new technology and fuels are introduced safely and effectively.
Encouraging innovation by working with industry on the development of sustainable aviation fuels, hydrogen, electric flight, and more efficient operations. - Sharing clear, trustworthy information with passengers and the public about aviation’s environmental impact, so choices and policies can be informed by evidence.
By combining regulation, technical expertise, and transparent communication, we aim to support innovation while safeguarding people, the environment, and the integrity of the UK’s aviation system.
Airspace Change
Information on how the environment is taken into account in the airspace change process can be found in CAP 1616 and on the following pages
Airspace Modernisation Strategy
Airspace modernisation - The vision of the Airspace Modernisation Strategy 2023–2040 (AMS) is to deliver quicker, quieter and cleaner journeys and more capacity for the benefit of those who use and are affected by UK airspace. A key strategic objective of the AMS is that environmental sustainability will be an overarching principle applied through all airspace modernisation activities. Airspace modernisation should deliver the Government’s key environmental objectives with respect to air navigation as set out in the Government’s Air Navigation Guidance and, in doing so, will take account of the interests of all stakeholders affected by the use of airspace.
Information on how the environment is taken into account in the Airspace Modernisation Strategy and in the airspace change process can be found in CAP 1616 and on the Airspace modernisation pages.
Air Navigation Services
In carrying out our duties around the economic regulation of air traffic services, we have a primary duty to maintain a high standard of safety and a secondary duty to take account of any guidance on environmental objectives given to us by the Secretary of State (among other secondary duties). The regulated UK air navigation services provider NATS (en route) Plc (NERL) must demonstrate that the costs of investments in sustainability initiatives are efficient.
Information on how the environment is taken into account in the economic regulation of NERL can be found on the NERL pages.
Information on environmental considerations in relation to air navigation services can be found on the following Air navigation services pages.
Airports
n carrying out our duties around the economic regulation of airports, we have a primary duty to further the interests of consumers and a secondary duty to have regard to the need to secure that the operators of Heathrow and Gatwick Airports are able to take reasonable measures to manage environmental impacts (among other secondary duties).
Information on how the environment is taken into account in the economic regulation of Heathrow and Gatwick Airports can be found on the Economic Regulation and Competition Policy pages.
Consumer Environmental Information
Many consumers want to have environmental information that they can trust about the impact of their flights. This was made clear in the consumer research we carried out in 2021.
We are working on standardising and improving the environmental information that could be provided to consumers when they are looking for and booking flights. This includes the method of calculating the CO2 emissions caused by aviation and how that information could be presented to consumers in a way that is accurate, understandable, standardised, comparable, accessible, and useful.
The overall aims of the project are:
- To provide consumers with environmental information to inform their travel choices; and
- To encourage industry to invest in reducing aviation emissions.
Consumers can currently find several different calculations of how much CO2 a flight might produce (and their individual share of that total), with little or no explanation of why a flight on one airline appears to have a significantly different amount of CO2 than another on the same route. There is also little explanation of what the information means in practice.
This work links to wider work by the UK government through its Jet Zero Strategy and is a key action in our Sustainability Strategy.
Project update
We published a Call for Evidence in early 2023 and we received over 120 responses from organisations and individuals. Following this consultation, we published a summary of responses.
In July 2024, we published a consultation on draft principles for aviation consumer environmental information.
Jet Zero Task-force
The Government has set up a taskforce with members from across the aviation industry, academia, environmental groups and other key stakeholders to coordinate and drive forward the actions needed to enable the aviation sector to meet its net zero targets.
More information on Government’s plans can be found in our UK Aviation Environmental Review
Sustainable Aviation Fuels (SAF)
Sustainable Aviation Fuel (SAF) is an alternative to conventional jet fuel, made from renewable sources like used cooking oil, agricultural residue, or waste materials, or through processes like "power-to-liquid" using captured carbon and renewable energy. SAF significantly reduces greenhouse gas emissions over its lifecycle compared to fossil jet fuel and can be blended with traditional fuel for use in existing aircraft without engine modification. While burning SAF still releases CO2, the carbon comes from sources that have already absorbed it from the atmosphere, leading to a significant reduction in net greenhouse gas emissions over the fuel's lifecycle compared to fossil fuels.
The UK Government published a SAF Mandate requiring the increasing use of SAF in the UK aviation fuel supply. Sustainable Aviation Fuel (SAF) Mandate - GOV.UK
The CAA’s main role in relation to SAF is in granting permission for test flights using blends of SAF that are greater than the permitted blend ratio.
The guidance listed below is explains what is needed to carry out trial flights using SAF blends that do not meet the current standards.
The CAA runs a short course on SAF: https://caainternational.com/course/introduction-to-sustainable-aviation-fuels/
Aircraft certification
The guidance listed below is available if you are designing a new aircraft, a new part, modifying an existing aircraft or maintaining one.
Where to find Data
Greenhouse Gas Emissions
Airlines and airports are not required to publish their emissions, but a growing number choose to do so voluntarily. There are therefore no official reporting standards, but most choose to report data as CO2e (CO2 equivalent, which includes other greenhouse gases).
Sources of information include:
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The CAA’s UK Aviation Environmental Review includes information and data on aviation emissions.
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Data published by specific airports or airlines can be found on their respective websites
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Some companies participate in the Carbon Disclosure Project, a global self-disclosure system.
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Sustainable Aviation, an industry body, reports annually on its members' performance, showing absolute CO2 emissions and efficiency.
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The Climate Change Committee has published several reports that provide information on aviation in relation to the Government’s Net Zero 2050 target.
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Aviation emissions are also reported as part of the Department for Energy Security and Net Zero’s UK Greenhouse Gas Emissions Statistics.
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Flight operators in the European Economic Area are required to submit data under the EU Emissions Trading System. The European Commission publishes annual lists of emissions for those participating in the scheme.
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The UK National Atmospheric Emissions Inventory (NAEI) run by the Department of Energy Security and Net Zero (DESNZ), includes some data on carbon emissions from aviation.
Interpreting the data
Emissions calculations often use assumptions due to the absence of complete data. Some factors to be aware of when studying and comparing emissions data include:
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Differences in calculation methods: when comparing emissions data, it is important to ensure that the calculation method used is the same. Different organisations use varying methodologies. For example, the UK Government uses airline fuel sale figures with a conversion factor, while airlines typically use fuel burn data with a conversion factor.
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Risk of double counting: different organisations may report the same emissions.
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Different forecasts also use varying assumptions and methodologies which should be taken into account when analysing such data.