Europe’s air traffic management airspace modernisation research arm, SESAR 3 Joint Undertaking, has released a multiannual work programme from 2022-2031. The document establishes the framework under which the operations of the Single European Sky Research SESAR 3 JU will be defined, planned and executed from 2021 to 2031. Two of the nine flagship technological solutions needed to achieve the modernisation and digitalisation of air traffic management in Europe in line with the European ATM Master Plan relate to U-space, UAM and associated technology.
According to the document: U-space provides an unparalleled opportunity to experiment, test and validate some of the key architectural principles and technology enablers of the future Digital European Sky before incorporating them into the broader ATM ecosystem. It can potentially help de-risk and accelerate the digital transformation of the European ATM system while opening the way to the safe integration of new vehicles into the airspace. UAM is expected to be the most challenging type of operations supported by U-space. UAM will enable on-demand highly automated operations of drones and larger eVTOL vehicles over urban areas, providing cargo, emergency and passenger transportation. Plans are afoot to deploy UAM in many European cities, with small-scale cargo operations already taking place and initial passenger services expected to launch by 2025. UAM will involve new types of vehicles with heterogeneous performances and high levels of autonomy, which will have to coexist with conventional manned traffic and will need to be accommodated by the U-space and ATM ecosystems.
The main research & innovation (R&I) challenges required to deploy U-space will include the following 12 R&I needs that have been identified in relation to this flagship topic:
Mature, validate and deploy across Europe the basic U-space services
The set of U-space services has been divided into four levels (U1–U4) of increasing sophistication and complexity: U1, which includes services such as registration, remote identification and geofencing; U2, which encompasses services such as flight planning, flight approval, tracking and the interface with conventional ATC; U3, with advanced services supporting more complex operations in dense areas, such as traffic prediction and capacity management, as well as assistance for conflict detection and resolution (automated DAA functionalities); and U4, with services still to be defined that will support high levels of autonomy and connectivity, as well as integration with manned aviation and ATM.
Although descriptions of many services exist at U1, U2 and even U3 levels, and a CONOPS shows how they can fit together, work is still needed on validation, cost–benefit analysis and standardisation. Although different U-space architectures have been proposed, work is still required to assess different options and identify those that meet the full range of requirements by the different types of operations and that guarantee safe and secure interoperability, thereby enabling a pan-European competitive environment for the provision of U-space services. One of 96 SESAR 3 JU MULTIANNUAL WORK PROGRAMME the challenges is to enable the simultaneous operations of multiple USSPs in the same airspace. In addition to the definition of potential U-space architectures, preliminary implementations of U1 and U2 services have already been demonstrated in the SESAR 2020 programme. Eurocontrol is collecting data from States to assess their progress towards deployment (as part of the EU network of U-space demonstrators’ initiative, led by the European Commission), which has so far been limited. Many questions still need to be answered before full-scale deployment is feasible, particularly in the areas of interoperability, certification and performance requirements, safety and security, fairness, contingency management, financing and liability.
Develop advanced U-space services
In parallel with the full validation, industrialisation and deployment of the basic U-space services, work needs to start on the definition, design and development of advanced services. The most advanced U-space services (U3/U4) will enable UAM missions in high-density and high-complexity areas. The required technologies to enable performance-based CNS services in U-space need to be identified and assessed in operational environments. For example, the use of mobile communication technology, such as 5G, and other emerging technologies for connectivity should be studied, as well as data-link solutions to enable electronic conspicuity and surveillance. Different solutions for separation management for all types of vehicles in all types of airspace (including airborne DAA, as well as ground-based and hybrid, solutions) should also be considered.
Enable urban Air Mobility (UAM)
The requirements of UAM operations are expected to be the most challenging for the U-space ecosystem. One of the key research questions is how to integrate the airspace autonomous operations over populated areas safely into complex and congested airspace environments, with operations involving vehicles interacting with U-space and conventional ATM services. Research should investigate how U-space can support the transition from piloted to autonomous operations (linked to EASA AI Regulatory Roadmap37). The evolution of U-space together with its associated regulatory framework and standards will need to be synchronised and coordinated with the development of the future UAM ConOps, its associated UAM services and the certification of UAM vehicles. Special consideration should be given to the operational limitations of these new vehicles and how U-space can contribute to operational safety by protecting their operation in contingency and non-nominal situations. In addition, mechanisms and protocols to enable Collaborative Decision Making in the context of UAM, involving ATM, U-space and city stakeholders, will need to be explored.
ATM/U-space integration
U-space services should enable safe and efficient operations of unmanned aircraft without negatively impacting the operations of other airspace users. The seamless integration of U-space and ATM services is expected to contribute to the fairness, safety, efficiency and environmental impact of the overall air traffic system. The capacity benefits and flexibility of an airspace without segregation requires the full integration of U-space and ATM. For U-space and ATM environments to be integrated, it does not necessarily mean they operate in the same way. They could be very different indeed, but with suitable interfaces to allow safe and effective coexistence. Standard operating procedures will need to be defined (e.g. rules of the air and airspace management) to allow manned and unmanned aircraft to share the same airspace safely, as well as the simultaneous provision of U-space and ATM services). The safety, security, certification and regulatory challenges arising from the provision of U-space services to manned aircraft should be studied. Information exchange will be critical to enable a safe convergence of U-space and ATM. Challenges include cybersecurity, data compatibility and the reconciliation of different standards and certification requirements. Another critical aspect of the integration will be the role of the human, particularly regarding the high level of automation that will be delivered by U-space services and the automation disparity between ATM and U-space.
In addition to the key challenges described above, the following transversal research areas will be critical to the successful development and deployment of U-space.
Financial and legal aspects
Research needs to be conducted on potential U-space and drone operator business models, focusing on the mechanisms required to create a fair and competitive U-space market across Europe. The available alternatives for the financing of a sustainable 37 Artificial Intelligence Roadmap, A human-centric approach to AI in aviation”, version 1.0, European Union Aviation Safety Agency, February 2020 97 ANNEXES U-space ecosystem should be analysed, including how to optimise public and private investments and the implications for the financial model of European ANSPs. The insurance models required for U-space should also be analysed.
Social acceptance
Work is required to ensure that the new operations enabled by U-space are acceptable to the public. Specific areas of concern will be UAM noise, visual pollution, privacy, etc. In addition, a consensus must be reached on the acceptable target level of safety of the different types of operations under U-space. The impact on general and leisure aviation should also be considered.
CNS and separation minima
Work is required on the definition and validation of performancedriven CNS requirements for operations under U-space, together with the applicable separation minima. The separation minima will be related to the CNS performance, available separation management services and other relevant criteria – ground risk, vehicle performance, etc. The validation of CNS technologies against the performance criteria will be required.
Support the development of the U-space regulatory framework and required standards
Leverage extensive modelling, simulation and experimentation to assess the maturity and interoperability of U-space services, assess different deployment options and support their industrialisation and deployment. Create U-space test centres offering an environment for stakeholders to conduct reproducible and interoperable tests in conditions comparable to live operational scenarios, with the objective of validating standards and regulations in representative environments. Such centres can also support the certification of new USSPs, services or technologies, making it possible to increase flexibility for rapid and agile increments of the U-space ecosystem.
Transfer of U-space automation technology to ATM
Explore whether U-space can be an accelerator of the ATM innovation life cycle, facilitating faster, lower-risk adoption of new technologies or approaches (automation, AI, cloud, etc.).
U-space performance framework
A performance framework for U-space needs to be defined in concordance with the overall SES performance framework, so as to assess and guide the deployment process based on objective and quantifiable performance measurements.
Safety assurance
New safety modelling and assessment methodologies applicable to U-space are needed. Tools are required to analyse and quantify the level of safety of U-space operations involving high levels of automation and autonomy, where multiple actors automatically make complex, interrelated decisions under uncertainty (e.g. weather-related uncertainty). Research is needed to ensure that the distributed decision-making protocols implemented in U-space achieve the required level of safety while catering for differing levels of experience of participants. Examples of approaches that could be leveraged for this purpose include greater use of simulation and machine learning applications such as stress-testing.
Applications above VLL airspace
Explore potential applications and extensions of U-space concepts beyond VLL airspace, for example to support manned traffic in uncontrolled airspace or to enable high-altitude operations.
Over the next 10 years, the implementation of this SRIA aims to unlock the potential of the drone economy and enable UAM on a wide scale. To that end, a new ATM concept for low altitude operations needs to be put in place to cater safely for the unprecedented complexity and high volume of the operations that are expected. This concept, referred to as U-space, will include new digital services and operational procedures and its development has already started within the SESAR 2020 programme. U-space is expected to provide the means to manage, safely and efficiently, high-density traffic at low altitudes involving heterogeneous vehicles (small UAVs, eVTOL aircraft and conventional manned aircraft), including operations over populated areas and within controlled airspace. U-space will have to integrate seamlessly with the ATM system to ensure safe and fair access to airspace for all airspace users, including UAM flights departing from airports. The development of U-space will have to overcome extraordinary challenges. A new regulatory framework, supported by a comprehensive set of standards, has to be established to provide a solid framework for safety and interoperability without hindering innovation. U-space will have to integrate seamlessly with the ATM system to ensure safe and fair access to airspace for all airspace users. This integration will not be straightforward since the requirements on U-space services may not be compatible with those imposed on ATM. To cater for the anticipated volume of operations, U-space will need to rely heavily on automation and to take advantage effectively of emerging onboard capabilities and advanced digital technologies on the ground. In addition, U-space is expected to have a profound socioeconomic impact, enabling the creation of a new marketplace for U-space service provision and accelerating the advent of the drone and UAM economy. Ultimately, the development and deployment of U-space will help position Europe as the global leader in UAM and drone-based services, accelerating the development and adoption of new technologies (AI, cloud, digital services, big data) and fostering the creation of high-quality jobs.
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