Project results are expected to contribute to the following expected outcomes.

• Environment: the proposed solutions are expected to contribute to the achievement of the objectives of a 55 % reduction in greenhouse gas emissions by 2030 and net-zero greenhouse gas emissions by 2050, from a gate-to-gate perspective, by introducing new concepts enabling proper modelling of non-CO₂ emissions and their impact on optimum green trajectories, taking into account the expected interoperability with new entrants (i.e. U-space flights). The objective is not only limited to foster greenhouse gases reduction but also to reduce noise and air pollution;
• Capacity: the proposed solutions are expected to rely on high automation to reduce controller workload to improve capacity, which will then allow optimal and environmentally-friendly flight trajectories;
• Cost-efficiency: saving fuel for airspace users will reduce CO₂ emissions and related costs for emission allowances.

The European Green Deal has set the objective of net-zero greenhouse gas emissions by 2050, in line with the EU’s commitment to global climate action under the Paris Agreement. To achieve this objective it is required to accelerate the shift to smarter and more sustainable mobility. The challenge is to achieve zero inefficiencies due to ATM by 2040: this means not only eliminating inefficiencies in the current system but also in the design and execution of the future ATM and U-space architecture. Proposals shall define and develop innovative solutions that could cover a wide variety of aspects e.g., operational measures that could be put in place to improve the fuel efficiency of flights, speeding up the modernisation of the air infrastructure to offer more capability and capacity and therefore offering more efficient trajectories, adapting the charging scheme to incentivise environmentally friendly operations, etc. The scope covers as well innovative ideas to accelerate decarbonisation of ATM and reduce the CO₂ and non-CO₂ emissions, through the integration of energy, transport and digitalisation platforms that are at the base of the green transition.

The SESAR 3 JU has identified the following innovative research elements that could be used to meet the challenge described above and achieve the expected outcomes. The list is not intended to be prescriptive; proposals for work on areas other than those listed below are welcome, provided they include adequate background and justification to ensure clear traceability with the R&I needs set out in the SRIA for the aviation Green Deal flagship.

• Atmospheric physics for aviation (non-CO₂) emissions, noise and air quality pollutants. Further understanding of non-CO₂ effects (climate metrics) and associated uncertainties is needed. This element covers research to increase the body of knowledge on the physics of the atmosphere, to better understand the impact on global warming of non-CO₂ emissions (NO_x, SO_x, H₂O, particulate matter, etc.), including contrails and aviation-induced cloudiness. The non- CO₂ climate impact of aviation exhibits large uncertainties. Among others, they include the uncertainty in the meteorological forecast, the uncertainty associated to the calculation of climate effects and impact, the selection of the emission model, or the model parameterisations required for development of efficient MET services. Research should aim in particular to reduce the uncertainty associated with the radiative forcing effects of aviation emissions identified in the 2020 European Commission report on the non-CO₂ impacts of aviation (https://www.easa.europa.eu/document-library/research-reports/report-commission-european-parliament-and-council). Investigate the relationship between atmospheric conditions at time of emission and subsequent non- CO₂ climate effects. Close coordination with EASA is expected, to ensure complementarity and consistency with EASA activities. Research may include:
  • The definition of an adequate physical climate metric which is able to assess (quantify) climate effects of future emissions;
  • The comparison in terms of quality of current meteorological forecasts, as well as of individual approaches presented so far by previous research initiatives e.g., FlyATM4E in order to provide a quantitative measure of the climate effects of aviation emissions, comprising contrail (cirrus) effects, NOx-induced effects, direct effects of water vapour emissions and aerosol induced effects;
  • The evaluation of radiative transfer modelling, which determines climate effects of aviation emissions;
  • The assessment of models of contrail life cycle and comprehensive chemistry-climate modelling involving representation of reactive species and aerosols, which influence radiative transfer in the atmosphere;
  • Improve and systematically evaluate the quality of the weather forecast to represent those key meteorological fields, which are relevant for climate effects of aircraft emissions (e.g., upper tropospheric humidity, ice water content or representation of ISSR) as well as background concentration of reactive species;
  • The quantification of impacts on non-CO2 effects from different blending ratios of different types of sustainable aviation fuel (SAF) (e.g., HEFA, FT-SPK, etc.);
  • Explore possible options to evaluate and validate contrail formation and atmospheric conditions, by e.g., satellite products. This will allow gaining confidence in radiative effects induced, but also identify success of alternative routing strategies, which aim e.g., to avoid warming contrails as could be explored during live trials.

Research shall take into consideration the output of SESAR projects FlyATM4E, SINOPTICA and ALARM, and other non-SESAR projects, which outcomes are fully relevant on this research element e.g., ACACIA (research on transport patterns of nitrogen oxides NO_x) and ClimOP. In addition, research shall ensure coordination with project CICONIA funded under call HORIZON-SESAR-2022-DES-ER1.

Research also aims at increasing the body of knowledge on the impact of ATM on areas such as noise and air quality pollutants (nitrogen oxides (NO_X), particulate matter (PM), volatile organic compounds (VOCs), sulphur dioxide (SO₂), carbon monoxide (CO) and unburnt hydrocarbons (HC)). Research aims at better understanding the ATM environmental impacts beyond greenhouse emissions (CO₂ and non-CO₂ aviation emissions). In particular considering that in the near future there will be new types of aircraft propulsions, new aircraft configurations and new propulsion fuels (e.g., hydrogen), whose impact on noise and air quality need to be researched (R&I need: non-CO₂ impacts of aviation).

• Noise and air quality pollutants. Research aims at increasing the body of knowledge on the impact of ATM on areas such as noise and air quality pollutants (nitrogen oxides (NO_X), particulate matter (PM), volatile organic compounds (VOCs), sulphur dioxide (SO₂), carbon monoxide (CO) and unburnt hydrocarbons (HC)). Research aims at better understanding the ATM environmental impacts beyond greenhouse emissions (CO2 and non-CO2 aviation emissions). In particular considering that in the near future there will be new types of aircraft propulsions, new aircraft configurations and new propulsion fuels (e.g., hydrogen), whose impact on noise and air quality need to be researched (R&I need: non-CO₂ impacts of aviation).
• Comparative study on potential metrics to be adopted in the ATM domain to aggregate non-CO₂ and CO₂ impacts on climate change. The study should cover, for example, global warming potentials (GWP) 100, average temperature response (ATR) 20, ATR 50, ATR 100, radiative forcing index (RFI) and alternative metrics, taking as a starting point the options outlined in the 2020 European Commission report on the non-CO₂ impacts of aviation. Proposals should include an initial task to review the state of the art of environmental metrics and engage with all relevant stakeholders in order to provide insights into the pros and cons of each potential metric, with the aim of formulating informed recommendations for the way forward, including the identification of additional research needs if applicable. This research should consider how metrics can be used in different contexts, for example for operational decision-making in the pre-tactical and tactical phases of ATFM, operational decision-making in real time by ATC, post-operations analysis and environmental performance monitoring at network level. Close coordination with EASA is expected, to ensure complementarity and consistency with EASA activities. In addition, the proposed climate metrics should be able to assess (quantify) climate effects of future emissions (and not only of historic emissions e.g., as done in the radiative forcing concept) by e.g., evaluating atmospheric response (temperature change) after a dedicated time horizon (e.g., 20, 50, and 100 years). Research shall take into account the output of project FlyATM4E (R&I need: non-CO₂ impacts of aviation).
• Atmospheric physics for aviation (extreme weather events). This element focuses on climate resilience and adaptation, as it aims at increasing the body of knowledge on the physics of the atmosphere, to make it possible to better predict extreme weather events that may impact aircraft operations, and in particular cause airport closures or significant reductions in airport capacity (with knock-on effects on the network). The research should in particular consider the challenges for accurate prediction that may result from changes to weather patterns arising from global warming in the short to medium-term. Research may also address the knowledge gaps in the understanding of the links between long-term climate change and risks to the aviation sector required to achieve a coherent strategy and short-term decision-making. These gaps have been reported in the “ICAO CAEP aviation and climate change factsheet” and the "European aviation environmental report 2022”. It is important to address these long-term links to allow ATM become more resilient, and assure that ATM short term induced decision will not jeopardise long-term ATM resilience and sustainability (R&I need: accelerating decarbonisation through operational and business incentivisation).
• Environmental impact assessment methodology and new metrics. It is necessary to develop further the methodology used in SESAR 2020 not only to cover the research phase, but also the deployment and implementation phases. As part of this methodology, the use of big data analysis and machine learning should be extended to the development of new environmental metrics that will be used to monitor environmental impacts and incentivise actors to promote compliance with environmental targets and regulations. These metrics will also be integrated into the environmental dashboard, and into the environment impact assessments toolset. Research shall consider as well the European Aviation Environmental Report. Research shall take into consideration the SESAR environmental performance assessment methodology (R&I need: accelerating decarbonisation through operational and business incentivisation).
• Development of the environmental performance-monitoring toolkit to include new entrants. There is a need to develop further the set of European environmental impact assessment tools, in order to analyse, inter alia, the integration of new entrants into the future ATM system and the overall environmental benefits and impacts they will have. This element covers the expansion of the ATM aircraft performance models (on emissions and noise) to include new entrants and new aircraft types/fuels. It involves research into the impact on the environment of new fuels and/or new aircraft types (hydrogen, electric, sustainable aviation fuels, new hyper-/supersonic aircraft (with consideration of sonic booms)), including the development of new models to assess the impact that ATM operational changes may have when these aircraft are introduced into the traffic mix. It should also include the development of methodologies to assess the environmental and societal impact of U-space-enabled drone operations, including in particular the identification of all potential impacts (e.g., visual pollution, noise over populated areas, intrusion into privacy, risks to wildlife (migrating birds, nesting areas, etc.)). Due to the complexity and diversity of environmental impacts, particular attention needs to be paid to the analysis of trade-offs, between environmental impacts, but also possibly with other performance areas (R&I need: impact of new entrants).
• Impact of zero-emission aircraft on ATM. The advances in the development of electric and hydrogen-powered propulsive systems support the future vision of air transport without any direct carbon emissions, thereby contributing to the Green Deal goal. It is anticipated that hydrogen and electric-powered flights will carry lower payload and may have requirements for longer turn-around times. Their performance will also be different from that of conventionally powered aircraft. Their introduction will fundamentally change the traffic demand that will have to be managed by the ATM system. There is a need to define scenarios of future fleet composition, model the resulting air traffic demand, evaluate the reduction of the environmental footprint enabled in each of the scenarios (considering direct and indirect emissions), analyse the implications of these changes on the airspace structure and the ATM system, and outline potential solutions for their adaptation. It is also relevant to explore the implications for airline operations that may impact ATM processes e.g., longer turnaround/airline scheduling, new flight planning/flight plan acceptance processes. New network management processes and changes to airport capacity also need to be considered. The research shall be tightly focused on the ATM dimension; impact of ATM on other relevant domains, or impact of ATM constraints on other domains may be addressed, but this should not be the core objective of the project. Integration of the new aircraft models into ATM models is in scope, but development of aircraft/propulsive systems and/or aircraft/propulsive system models is out of scope (the research should use aircraft/propulsive system models developed prior to the start of the project). The goal of this research is to inform policymakers, industry leaders, and researchers about the potential R&D needs to allow the safe integration of zero emission aircraft in the ATM system (R&I need: impact of new entrants).
• New forms of air traffic management. Research aims at exploring new forms of air traffic management to support the integration of highly automated vehicles and autonomous aircraft e.g., high altitude platform systems (HAPS), aircraft with new propulsion systems (electric/hydrogen), unmanned aircraft systems, recreational flying vehicles and other new entrant operators while minimising their environmental impact, in terms of greenhouse gases emissions, noise and air pollutants. Research shall take into consideration the variety of vehicle performances and their impact on traffic management (R&I need: impact of new entrants).