This appendix provides an overview of the data sources, models and assumptions used to develop the information presented in Overview of Aviation Sector, Technology and Design, Airports and Market-Based Measures chapters. These modelling capabilities have been developed and used to support various European initiatives, as well as international policy assessments in ICAO.
Scope
The information in this report covers all flights from or to airports in the European Union (EU) and European Free Trade Association (EFTA). For consistency, regardless of the year, the EU here consists of the current 27 member States: Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain and Sweden. EFTA members are Iceland, Liechtenstein, Norway and Switzerland. Airports in overseas territories are not included, except those in Azores, Canary, Madeira and Faroe Islands. Statistics for UK are therefore not included, also for the years preceding the Brexit.
Data Sources
EUROCONTROL Flight Data
Historical 2005-2023 flight operations were extracted from the EUROCONTROL database of filed flight plans. This covers all instrument flight rules (IFR) flights in Europe. Flight data are enriched with and validated against, for example, radar updates, billing data from the Central Route Charges Office and an internal database of global aircraft. Each flight is categorised into one of the market segments: scheduled flights are divided into “low-cost” and “traditional scheduled” until 2018 and into “low-cost”, “regional” and “mainline” from 2019 onwards1; “business aviation” captures flights by jets, turboprops and piston aircraft typically used for business aviation (mostly under 20 seats nominal size); “all-cargo” captures dedicated freighter flights; etc. These market segments are defined in terms of aircraft operator, aircraft type, ICAO flight type or callsign, as appropriate. The detailed definitions are available on the EUROCONTROL website.
Eurostat
European States collect statistics on air transport from their airports and airlines and provide these to Eurostat, which makes them public, although airline details are treated as confidential. Statistics on total activity (total passengers, total tonnes shipped, etc.) are as complete as possible. More detailed statistics, such as passengers and available seats for individual airport pairs, are focused on major flows. For example, we use these data to indicate trends in load factors, but we cannot calculate total available seat-kilometres solely from them. The estimates of total passenger kilometres flown in the Overview of Aviation Sector chapter are based on Eurostat directly, on analysis of other Eurostat flows and on data from the EUROCONTROL data warehouse. The great circle (i.e. shortest) distance between airport pairs is used when reporting passenger kilometres and calculating the average fuel consumption per passenger kilometre. The fuel consumption reported is however based on the actual distance flown. Consequently, the effect of ATM horizontal inefficiency is captured in the fuel efficiency indicator.
EUROCONTROL Aviation Long-term Outlook 2050
The EUROCONTROL Aviation Long-term Outlook 2050 published in December 2024 provided the flights and emissions forecast over the period 2030-2050 used in this report. It has three scenarios: the ‘high’ has strong economic growth with intense investment in technology to support sustainability, leading to relatively high growth in demand; the most-likely, ‘base’ scenario has moderate economic growth following current trends; the ‘low’ has slower economic growth and higher energy prices, leading to fewer flights and lower investment. As is usual for STATFOR forecasts, airports provided their future capacity plans, and the forecast traffic respects the capacity constraints implied by these plans, although the Outlook notes that increasingly the primary constraint is sustainability rather than capacity.
BADA
BADA (Base of Aircraft Data) is an Aircraft Performance Model developed and maintained by EUROCONTROL, in cooperation with aircraft manufacturers and operating airlines. BADA is based on a kinetic approach to aircraft performance modelling, which enables to accurately predict aircraft trajectories and the associated fuel consumption. BADA includes both model specifications which provide the theoretical fundamentals to calculate aircraft performance parameters, and the datasets containing aircraft-specific coefficients required to calculate their trajectories. The BADA 3 family is today’s industry standard for aircraft performance modelling in the nominal part of the flight envelope and provides close to 100% coverage of operations in the European region. The latest BADA 4 family provides increased levels of precision in aircraft performance parameters over the nearly entire flight envelope and covers 73% of operations in the European region. This report uses BADA 4 (release 4.2), complemented by BADA 3 (release 3.16) for aircraft types not yet covered in BADA 4.
Aircraft Noise and Performance (ANP) Database
The Aircraft Noise and Performance (ANP) database is maintained by EASA and the US Department of Transportation. It provides the noise and performance characteristics for over 160 civil aircraft types, which are required to compute noise contours around civil airports using the calculation method described in Annex II of European Directive 2002/49/EC relating to assessment and management of environmental noise, ECAC Doc 29 and ICAO Doc 9911 guidance documents. ANP datasets are supplied by aircraft manufacturers for specific airframe-engine types, in accordance with specifications developed by the ICAO. EASA is responsible for collecting, verifying and publishing ANP data for aircraft which fall under the scope of Regulation (EU) 598/2014. This report uses the legacy ANP 2.3 version (which was previously hosted and maintained by EUROCONTROL and has been recently transferred to EASA), complemented by the ANP datasets verified and published by EASA before September 2024.
EASA Certification Noise Levels
EASA maintains a database of all aircraft noise certification levels which the Agency has approved. The database provides certified noise levels for over 35 000 aircraft variants, including jet, heavy and light propeller aircraft as well as helicopters. In this report, the certified noise levels are used to assess the Noise Energy Index, to attribute an ANP airframe-engine type to each aircraft type in the fleet using the ECAC Doc 29 4th Edition recommended substitution method, as well as to create the noise charts in the Technology and Design and Airport chapters.
ICAO Aircraft Engine Emissions Databank
The ICAO Aircraft Engine Emissions Databank (EEDB) hosted by EASA contains Landing and Take-Off (LTO) emissions data for NOX, HC, CO, smoke number and non-volatile PM for over 450 jet engine types. The EEDB emission indices are used by the IMPACT model to compute NOX , HC, CO and PM, and to create the NOX charts in the Technology and Design chapter.
FOI Turboprop Emissions Database
The Swedish Defence Research Agency (FOI) hosts a database of NOX, HC and CO emission indices for turboprop engine types. The data was supplied by the turboprop engine manufacturers, originally for the purposes of calculating emissions-related landing charges. It is used to complement the ICAO EEDB for the NOX, HC and CO estimates in this report.
FOCA Piston Emissions Database
The Swiss Federal Office of Civil Aviation (FOCA) hosts a database of NOX, HC, CO and aggregated non-volatile and volatile Particles Matters emission indices for piston engine types. The data was measured and calculated by the FOCA. It is used to complement the ICAO EEDB for the NOX, HC, CO and Total Particles Matters estimates in this report.
CODA Taxi Times Database
EUROCONTROL’s Central Office for Delay Analysis (CODA) collects flight-by-flight data from around 100 airlines including actual off-block and take-off times and delay causes. The post-ops data collection started in the early 2000’s on a voluntary basis in return for performance and benchmarking reports, but increasingly the data collection is based on the mandatory data feed under the EU performance regulations IR2019/317, see also EUROCONTROL Specification for Operational ANS Performance Monitoring - Air Transport Operator Data Flow. CODA publishes aggregated performance statistics, such as on punctuality and all-causes delays from these data. The detailed actual taxi times from this source were used to assess taxi fuel burn and emissions.
Population Data
The JRC Global Human Settlement population spatial raster was used to estimate the number of people exposed to aircraft noise around airports. This dataset provides census data with a spatial resolution of 100 x 100 m and is multi-temporal, with a resolution of 5 years (1975 to 2030). For the past years (2005-2023), the population raster versions used were respectively 2005, 2010, 2015 and 2020. For all the future years and scenarios, the population distribution was then assumed to be unchanged over time by using the 2020 raster version.
Models and methods
IMPACT
IMPACT is a web-based modelling platform developed and hosted by EUROCONTROL to assess the environmental impacts of aviation (noise and emissions). It allows to compute full-flight trajectories with associated fuel burn and CO2 emissions thanks to an advanced aircraft performance-based trajectory model using a combination of ANP and BADA reference data. Other gaseous emissions such as NOX, HC, CO and PM emissions are computed using the LTO emission indices from the ICAO EEDB, FOI Turboprop and FOCA Piston Emissions reference databases, combined with the Boeing Fuel Flow Method 2 (BFFM2). PM emission indices of jet engines are estimated using the First Order Approximation (FOA4) method,2 which is detailed in the ICAO Airport Air Quality Manual (Doc 9889 2nd edition 2020). En-route non-volatile PM emissions3 are calculated using the up-to-date implementation of the black carbon emissions methodology,4 detailed by the nvPM Mission Emissions Estimation Methodology (MEEM).5 The IMPACT calculation methods and reference data to assess fuel burn and emissions may differ from those used by Member States to report their emissions to UNFCCC or CLRTAP, hence the delta in estimates between these data sources.
SysTem for AirPort noise Exposure Studies (STAPES)
STAPES is a multi-airport noise model jointly developed by the European Commission, EASA and EUROCONTROL. It consists of a software compliant with Annex II of Directive 2002/49/EC and the 4th Edition of the ECAC Doc 29 modelling methodology, combined with a database of over 100 airports with information on runway and route layout, as well as the distribution of aircraft movements over these runways and routes. The STAPES airport database also includes airport-specific aircraft vertical flight profiles and noise-power-distance (NPD) data, which reflect the average local atmospheric conditions at each airport in terms of temperature, pressure, wind speed and relative humidity.
Aircraft Assignment Tool (AAT)
AAT is a fleet and operations forecasting model jointly developed by the European Commission, EASA and EUROCONTROL. AAT converts a passenger and flight demand forecast into detailed operations by aircraft type and airport pair for a given future year and scenario, taking into account aircraft retirement and the introduction of new aircraft into the fleet. It is an integral part of the STATFOR long-term forecast methodology that was followed for the 2050 outlook. The forecast operations are processed through the IMPACT and STAPES models to assess the fuel burn, emissions and noise data for years 2030 to 2050 presented in the Overview of Aviation Sector chapter.
EASA AERO-MS
The AERO-MS is a tool developed specifically to support impact assessments for regulations to reduce greenhouse gas (GHG) emissions from aviation. The AERO-MS assesses the economic and environmental impacts of a wide range of policy options to reduce international and domestic aviation GHG emissions. Policy options that can be examined include the different taxation (including fuel and ticket taxation), emission trading schemes (such as the EU ETS) and offset schemes like CORSIA, the introduction of Sustainable Aviation Fuels (SAFs) and air traffic management (ATM) improvements. Such policy options, the model shows, can affect both the supply side and demand side of the air transport sector. The AERO-MS forecasts the impact on emission reductions of measures and policies but also the extent by which demand for air travel is reduced due to these higher prices. The AERO-MS has a global scope; the analysis is built on a Unified Database containing a detailed record of global aviation movements in the Base Year. As part of the latest AERO-MS update completed in 2024, the Base Year data in the AERO-MS relate to 2019. The Unified Database for 2019 records over 113 000 airport-pairs, covering a full network of all key airports, derived from the EUROCONTROL Database for European flights and Flightradar24 data for the rest of the world. Airline cost and fare data are based on relevant data from the International Air Transport Association (IATA) and the International Civil Aviation Organisation (ICAO). Aircraft type input data is based on the Cirium aircraft registration database and the ICAO aircraft engine emissions databank. For the specification of aircraft operational characteristics use is made of the EUROCONTROL BADA4 data
Assumptions
Fuel burn, emissions and noise assessment
For consistency with other international emission inventories, full-flight emissions presented in this report are for all flights departing from EU27 or EFTA, i.e. flights coming from outside EU27 or EFTA are not included. In contrast, noise indicators include all departures and all arrivals. Historical fuel burn and emission calculations are based on the actual flight plans from the EUROCONTROL Flight Data, including the actual flight distance and cruise altitude by airport pair. Default aircraft take-off weigts from the ANP database (defined as a function of trip length) are used when assessing noise, fuel burn and emissions for this report; these may not always reflect the load factors and take-off weights observed in real operations. Future year fuel burn and emissions are based on actual flight distances and cruise altitudes by airport pair in 2023. Future taxi times are assumed to be identical to the 2023 taxi times; where non available, ICAO default taxi times are applied. Helicopter operations are excluded from the assessment.
The calculation of the Lden, Lnight and N50 A70 noise indicators was performed with the STAPES model over 98 major EU27+EFTA airports6 (see below map) representing about 86% of the total landing and take-off noise energy emitted in the region during 2023.
The runway and route layouts of each airport were assumed to be constant over the full analysis period – i.e. only the fleet, the number and time of operations vary. The standard take-off and landing profiles in the ANP database were applied. For historical noise, the day/evening/night flight distribution was based on actual local departure and landing times assuming the Environmental Noise Directive default times for the three periods: day = 7:00 to 19:00, evening = 19:00 to 23:00, night = 23:00 to 7:00. For future years, the day/evening/night flight distribution at each airport was assumed to remain unchanged compared to 2023. For each year in the historic airport noise exposure reporting, the latest census year of the population spatial raster multitemporal dataset was used e.g., the 2005 dataset was used for years 2005 to 2009, the 2010 dataset was used for years 2010 to 2014, etc. Future airport noise exposure estimates were all based on the 2020 census dataset, i.e. the population density around airport was assumed to remain constant after 2020. The mapping of the fleet to the ANP aircraft follows the ECAC Doc 29 4th Edition recommended substitution method.
In addition to the noise contours at the 98 airports modelled in STAPES, the noise generated by aircraft take-offs and landings at all airports in the EU27 and EFTA area was estimated via the Noise Energy Index, by applying the following formula:
where
Ndep and Narr are the numbers of departures and arrivals by aircraft type weighted for aircraft substitution;
LAT, FO and APP are the certified noise levels in EPNdB at the three certification points (lateral, flyover, approach) for each aircraft type.7
Noise dose-response curves
To estimate the total population highly annoyed (HA) and highly sleep disturbed (HSD) by aircraft noise, the following
dose-response regression curves recommended by WHO for the European region were used:
Share of population highly annoyed (%HA) = -50.9693 + 1.0168 * Lden + 0.0072 * Lden2
Share of population highly sleep disturbed (%HSD) = 16.79 - 0.9293 * Lnight + 0.0198 * Lnight2
The total population at the 98 major airports in STAPES was assessed for Lden threshold values between 45 and 75 dB and for Lnight values between 40 and 70 dB with one decibel increment, and then multiplied by the corresponding %HA and %HSD values. As the Lden and Lnight values represent outdoor noise levels the annoyance and sleep disturbance estimates may not take into account the effect of local sound insulation campaigns for houses and buildings around airports.
Map of the 98 airports included in the EAER noise contour calculations
Future fleet technology scenarios
Future noise and emissions presented in the Overview of Aviation Sector chapter were assessed for different technology scenarios.
The most conservative ‘frozen technology’ scenario assumes that the technology of new aircraft deliveries between 2023 and 2050 remains as it was in 2023. Under this scenario, the 2023 in-service fleet is progressively replaced with aircraft available for purchase in 2023. This includes the A320neo, B737 MAX, Airbus A220 (or Bombardier CSeries), Embraer E-Jet E2, etc.
On top of the fleet renewal, technology improvements for fuel burn (CO2), NOX and noise are applied on a year-by-year basis to all new aircraft deliveries from 2023 onwards following an average technology scenario. This technology scenario was derived from analyses performed by a group of independent experts for the ICAO CAEP and is meant to represent the nominal noise and emission reductions that can be expected from conventional aircraft and engine technology by 2050.
For noise, the technology scenario used for this report assumes a reduction of 0.1 EPNdB per annum at each noise certification point for new aircraft deliveries. For fuel burn and CO2, the technology scenario assumes a 1.16% reduction per annum for new aircraft deliveries. For NOX, the scenario assumes a 50% achievement of the CAEP/7 NOX Goals by 2036 and that improvements continue at the same rate after, i.e. that NOX emissions of new aircraft deliveries reduce by 0.5% per annum until 2050. No technology improvement was applied when estimating future HC, CO and PM emissions.
The above technology scenarios represent improvements in conventional aircraft designs, i.e. they do not take into account potential future designs like supersonic aircraft, electric/hydrogen aircraft or UAVs. For the forecast of net CO2 emissions, electric/hydrogen aircraft were assumed to enter the fleet in 2035 and bring an additional emissions reduction gradually ramping up to 5% in 2050.
Future ATM improvements
The European ATM Master Plan, managed by SESAR 3, defines a common vision and roadmap for ATM stakeholders to modernise and harmonise European ATM systems, including an aspirational goal to reduce average CO2 emission per flight by 5-10% (0.8-1.6 tonnes) by 2035 through enhanced cooperation. Improvements in ATM system efficiency beyond 2023 were assumed to bring reductions in full-flight emissions gradually ramping up to 5% in 2035 and 10% in 2050. These reductions are applied on top of those coming from aircraft/engine technology improvements.
Future SAF scenario
The sustainable aviation fuels (SAF) assumptions used in the base traffic scenario forecast of net CO2 emissions (
) are based on the ReFuelEU Aviation Regulation and the Renewable Energy Directive (RED) as adopted by the European Commission in October 2023. This assumes that SAF supply gradually increases to 20% of total fuel supply in 2035 and 70% in 2050. The lifecycle CO2 emissions reductions, compared to fossil-based fuel, were assumed to be 65% and 70% for biofuels and RFNBOs respectively, which is in line with the minimum required reduction as defined in the RED sustainability criteria. These assumptions are different to those taken within the ReFuelEU Aviation Impact Assessment from 2021 and will be constantly reviewed in future EAERs, taking into account the annual reports published by EASA from 2025 under ReFuelEU Aviation on the evolving SAF market. It is also assumed that the use of SAF will not have any impact on NOX emissions.Future MBM scenario
The net CO2 reductions generated by market-based measures (EU ETS and ICAO CORSIA) in the period 2024-2026 were estimated using the AERO-MS model that was upgraded in 2024. The scope and timeframe of the modelling in
reflects the revised EU ETS Directive, i.e., flights within and between countries in the European Economic Area, as well as departing flights to Switzerland and to the United Kingdom, are covered by EU ETS, while CORSIA is applied for flights to and from third countries. EU ETS has also been applied for flights between countries in the European Economic Area and the outermost regions, as well as between the outermost regions, unless they connect to the respective Member State’s mainland. EU ETS also applies to flights from the outermost regions to Switzerland and the United Kingdom. Modelling also includes the gradual phase-out of the free ETS allocation to airlines as follows: 25% in 2024; 50% in 2025; and 100% from 2026, as well as applying an annual linear reduction factor of 4.3% to the EU Allowances issued for aviation from 2024 onwards.Regarding the modelled impact of Swiss ETS, the Swiss ETS covers domestic flights in Switzerland and flights from Switzerland to the EEA or the UK. CO2 emissions and allowances data of the Swiss ETS for the years 2020-2023 are taken from the website of the Swiss Federal Office for the Environment (FOEN). Modelled impacts of Swiss ETS are based on the proxy Mid Growth CAEP/13 scenario implemented in the AERO-MS. From 2024 onwards, flights from Switzerland to the outermost regions of the EU are no longer exempted from the Swiss ETS. The cap is reduced by 4.3% annually from 2024 onwards (linear reduction factor). Assumptions on free allocation for the period 2024-2026 are based on what is agreed for the EU ETS (i.e. 25% reduction in 2024; 50% reduction in 2025 and 100% reduction in 2026). It is also assumed that installations and aircraft operators in both the EEA and Switzerland can use both EUAs and CHUs to meet compliance obligations.
Estimated CORSIA offsetting requirements for departing flights from Europe in
covers departing traffic for all airlines from EEA countries to third countries that participate in CORSIA offsetting, except for flights to Switzerland and the United Kingdom, which are covered by EU ETS. Assumption on States’ participation to CORSIA offsetting in the CORSIA first phase is based on the list of CORSIA States for Chapter 3 State Pairs, published by ICAO,8 and the assumption on States’ participation in the second phase is based on maintaining the level of volunteering States in year 2025 plus the States that are required to join the second phase as per ICAO Assembly resolution A41-22.1 The “regional” segment includes commercial flights by a list of regional aircraft types (19-120 seats); the “mainline” one includes other scheduled flights.
2 Due to the lack of smoke number data for turboprop engines, PM estimates currently exclude this category. As an indication, turboprop aircraft represented approximately 1% of the total fleet fuel burn in 2023.
3 Non-volatile particulate matter (nvPM) refers to particles measured at the engine exit and is the basis for the regulation of engine emissions certification as defined in ICAO Annex 16 Volume II, emitted particles that exist at a gas turbine engine exhaust nozzle plane, that do not volatilize when heated to a temperature of 350°C.
4 Stettler, Marc E. J.; Boies, Adam M.; Petzold, Andreas; R. H. Barrett, Steven (2016): Global Civil Aviation Black Carbon Emissions. ACS Publications. Collection. https://doi.org/10.1021/es401356v
5 Ahrens, Denise & Méry, Yoann & Guénard, Adrien & Miake-Lye, Richard. (2022). A New Approach to Estimate Particulate Matter Emissions From Ground Certification Data: The nvPM Mission Emissions Estimation Methodology (MEEM). 10.1115/GT2022-81277.
6 From 2021 onwards, the number of airports is 97 due to the closure of Berlin Tegel airport in 2020 and the reallocation of its traffic to Berlin Brandenburg airport.
7 For Chapter 6 and 10 aircraft (light propeller), the unique overflight or take-off level is used for the three values.
8 CORSIA States for Chapter 3 State Pairs (icao.int)
