Regulatory perspectives on emerging higher airspace users

Higher Airspace Users

Giovanni Di Antonio, High Altitude and Access to Space Operations Regulation Team Leader at the Italian Civil Aviation Authority (ENAC) and Chair of the EASA Higher Airspace Operations Task Force, looks at the innovative regulatory approaches underway to integrate a new community of high airspace users.

The last decade has seen an increase in emerging airspace users, boosted by technological innovation, looking to exploit new commercial opportunities from very low level to very high level.

This includes drones and air taxis for Urban/Advanced Air Mobility, High Altitude Platform Systems (HAPS) for communication, surveillance and Earth observation, commercial space and suborbital vehicles for air-launching, experimentation and space tourism. Other new entrants are expected in the coming years, such as intercontinental pointto- point supersonic, hypersonic and suborbital aircraft, and re-entry-from-orbit vehicles.

To support this development, regulators are being called upon to rethink traditional paradigms and approaches to find new solutions according to Better Regulation principles, to allow a safe accommodation and integration of these new operations into the airspace without disproportionately affecting the current and future aviation sector.

While drone regulation is well underway in Europe, regulation for high altitude operations is still in its nascent phase – which may be an opportunity indeed – even if some States, like the UK, and partly Italy, have developed their national regulation in this domain having benefitted from the FAA experience in the US.

Higher airspace operations

Higher Airspace Operations (HAO) include all those operations (HAPS, supersonic and hypersonic flights, suborbital flights, aero-launching and vertical launching into orbit, and re-entry from orbit) which are carried out in the higher airspace, namely above the flight levels where traditional aircraft are controlled today, but not yet in outer space. The higher airspace concept is currently under discussion: there is not a clear consensus at the moment on a definition, mainly because of the absence of a legal boundary between airspace, where states may exercise their sovereignty over their territory according to the Chicago Convention, and outer space that cannot be subject to national appropriation by claim of sovereignty according to the Outer Space Treaty.

To get around this obstacle in a pragmatic way, a functionalist approach to regulation may help by focusing on regulating the specific operation(s) rather than establishing different rules or legal regimes for different altitudes.

European initiatives: The ECHO project and EASA HAO task force

In 2020, in response to a European Commission request, EUROCONTROL started the ECHO project for developing the European HAO concept of operation, and EASA set up the HAO Task Force to carry out preparatory work for future HAO regulation. This regulation is expected to be based on the High-level Principles developed during the first European Higher Airspace Operations Symposium held in Brussels on 2 April 2019 taking into account Member States’ experience.

Remarkably, among others, the High-level Principles need to “ensure the safe and orderly implementation of higher airspace operations using risk- and performance-based approaches to innovation and regulation when establishing the appropriate requirements for safety, security, contingency and resilience of operations for all phases of flight.”

EASA HAO Task Force is composed of EASA, national aviation authorities of interested EASA Member States, and the European Defence Agency (EDA) to ensure civil-military coordination1. The participation of the ECHO Programme Manager from EUROCONTROL as observer, ensures coordination with the ECHO Project. Its work programme extends to 2024 and foresees the development of a set of regulatory principles and assumptions, vehicles and operations categorisation, regulatory structure options, and an impact assessment that will lead to final recommendations on how the regulatory framework might be shaped.

ECHO project

Interested to learn more about the European concept for higher airspace operation (ECHO) project?

Regulatory approaches: Operation-centric vs Full-certification

Different approaches are needed for different situations. The modern operation-centric, risk-based and performance-based approaches could be used as possible alternatives to the traditional full-certification when possible and deemed appropriate. Whatever the approach, regulation should cover the risks posed by the operations to third parties on ground, in the air, in space, to people onboard, and critical infrastructure, while protecting the European States’ defence and strategic interests.

Following an operation-centric approach, it would be possible to issue one single operational authorisation to carry out one or more flights under the same scenario, vehicle configuration, infrastructure, conditions and limitations without the need to authorise every single element separately. The authorisation may be based upon the results of a holistic risk assessment that identifies a balanced set of technical and operational mitigating measures – including flightworthiness design provisions, if needed – to control all foreseeable hazards related to design, production, maintenance, operational procedures, personnel licences and training, infrastructure,and so on, up to an acceptable low-risk level compliant with the level of safety set by the regulator. This approach would then be suitable for experimental or specific State or commercial operations.

By contrast, the traditional full-certification approach is based on a prescriptive regulation that allows operations only when the vehicle and any other element of the operation has obtained the relevant certification issued by a competent authority.

Performance-based approach to occupants’ safety

Irrespective of the approach followed, flightworthiness requirements are needed to ensure vehicles integrity and occupants’ safety for human operations. They could be developed either in a prescriptive manner or by using a performance-based approach which is common today in general and unmanned aviation.

Prescriptive regulation contains detailed provisions and quantitative safety targets. Nevertheless, because the sector is in its nascent phase and there are very few reliability and occurrence data available, it might be not easy to set effective detailed requirements for different types of vehicles in a proportionate manner. Alternatively by developing performance-based requirements the regulator only sets qualitative safety objectives to be complied with by consensus standards developed by industry or standardisation bodies and approved by the authority that may better tailor to specific architectures, allowing innovative solutions.

Regulatory structures

We do not expect the same type of vehicle to adhere to different sets of rules for similar scenarios in different parts of Europe; rather, it might be desirable to have a unique risk-based regulation with common objective requirements to be met in different situations by using different technical and operational mitigating measures. This type of regulation could be built on two levels.

The first level might contain a common set of rules valid for all types of operation, such as Higher Airspace Traffic Management (HATM), air navigation services, air and space collision avoidance, interface with space traffic management(STM), organisations and safety management, occurrence reporting and investigation, etc.

The second level could be modular. Specific rules for different categories of vehicles and operations might cover aspects such as design, production, maintenance, operational procedures and personnel, and related supporting infrastructure on ground – such as spaceports – in the air and in space, with the aim to protect people on ground and occupants onboard.

In this framework, human and non-human operations which do not imply point-to-point passengers or goods’ transportation (HAPS, regional suborbital flight, aero-launching, vertical launching, re-entry), and experimental operations could follow a risk-based operation-centric approach as opposed to intercontinental point-to-point suborbital and hypersonic flights which could be regulated by a full-certification approach in the long term. These kind of options are going to be discussed by the EASA HAO Task Force in the coming months.

Main challenges

There are a number of challenges to be dealt within the HAO domain, namely: how to coordinate air law and space law; how to share responsibility between the EU and Member States; how to integrate the future HAO regulation with existing and under development drone regulation; how to regulate new services in the higher airspace and up to which altitude; how to set new rules of the air suitable for different vehicles’ performances; how to assure a fair and equitable access to higher airspace; how to set an appropriate level of safety for different vehicles and operations categories takinginto account the technology’s state-of-the-art, and how to set effective interfaces and coordination between ATM and STM, which is important to avoid collision with active space objects and space debris. Environmental issues shall have to be carefully considered as well by evaluating the impact both at the surface (e.g. at take-off and landing sites) and for the atmosphere (troposphere, mesosphere and thermosphere).

Special attention will have to be paid to those traditional space operations such as vertical launching and re-entry that fall in principle under national space laws. These operations are expected to be regulated for their transiting into the airspace and for sharing aviation infrastructure. One issue for HAO will be the degree of integration into the airspace in the medium and long term, in contrast to today’s segregation practice. Another will be whether the new HAO regulations should also deal with the safety of spaceflight occupants (e.g. in a re-entry flight), or if this aspect will remain under the remit of the States. In this respect, the clarification of the vehicle’s legal status (along with registration requirements) in the different phases of its operational life will be of particular importance, especially when it does not always behave as an aircraft or when it can be considered a space object, such as the Space Rider Re-entry Module.

Finally, to unlock operations, we will also have to tackle the issue of third-party liability and insurance, considering the potentially higher risk of HAO compared with traditional aviation, and their similarity with space operations; in this domain a conciliation between the aviation regime, that makes the operator liable, and space regime, that makes launching States liable, will be necessary.

All these challenges will require a coordinated and collaborative approach between aviation and space institutions, research bodies and industry in the coming years.

Moving forward

To ensure the future European HAO regulation is built on a solid foundation it will be of paramount importance to gather specific use-case information from States based on HAO experiences taking place in their territories in the near- and mid-term. At the same time, it will be essential to complete the European HAO concept of operations by the ECHO Project and the preparatory work for regulation by the EASA Task Force in order to eventually allow the formal EU legislative procedure to start within the next years. Moreover, the inherently global nature of HAO requires cooperation at international level, in particular with ICAO, to hopefully move – bottom-up – towards an increasingly consistent international framework able to support the necessary degree of interoperability.

Emerging users are emerging. An effective and flexible HAO regulation able to ensure a level playing field in terms of safety, security, equitable access to airspace and capability to accommodate or integrate present and future entrants without disproportionately affecting current aviation is then unavoidable. Unlocking HAO starting from today will foster innovation and support the growth of a new aerospace economy, allowing authorities to gain experience to continually improve the regulatory framework. To this end it will be essential that the European Union and national aviation authorities work together with space institutions and industry stakeholders in an increasingly coordinated manner, to exploit these opportunities in the coming years.


The opinions expressed in this article are those of the author and do not necessarily reflect the view of the EASA HAO Task Force or that of its members.

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