The higher airspace (airspace approximately 60,000 ft) is no longer exclusive to space rockets and military planes, but hosts an expanding range of vehicles, including long-endurance balloons, high altitude platform stations (HAPS), supersonic and hypersonic aircraft. With missions varying from connectivity and surveillance to passenger transport and satellite services, these vehicles with vastly different operating characteristics present a new airspace management challenge. In this article, Henk Hof, Eurocontrol and project coordinator of the SESAR 3 JU ECHO project, explains how the project partners are developing a concept of operations for the higher airspace.

The genesis came with the European Commission tasking the European Union Aviation Safety Agency (EASA) with preparing a regulatory framework and with partners coming together to set out some high-level principles during a Higher Airspace Operations Symposium organised by Eurocontrol in 2019. In November 2020, the two-year ECHO project was launched within the framework of the SESAR JU and Horizon 2020 to develop higher airspace ConOps. ECHO is supported by an advisory group, including EASA, the European Space Agency (ESA) and the European Defence Agency (EDA) that facilitates consistency between the regulatory framework and ConOps development.

ECHO is on track to deliver a comprehensive demand analysis and ConOps to allow safe, efficient and scalable operations. A key objective is to address operations of vehicles today as well as of vehicles and activities still to be developed, hence the project identifies short-, medium- and long-term timeframes and is expected to feed into ICAO efforts to develop global guidance material. ECHO project coordinator, Henk Hof, says the higher airspace provides an enormous opportunity for the airspace management industry generally. “We have a chance from the start to take a pan-European approach rather than a state or national perspective. Additionally, the absence of legacy technology presents a unique proving ground for innovation. It allows information sharing, collaborative processes, system-wide information management (SWIM), trajectory-based operations and other ICAO concepts to take a giant step forward.” Once they have been shown to work, these new concepts can then be made available for use in the airspace below.

First steps

Among ECHO’s first actions, the project released a series of principles and assumptions regarding higher airspace in early 2021. This sets out the safety objectives, airspace access, security and defence, civil-military coordination and interfaces with other airspace and air traffic management. This was discussed at the first of three workshops involving the whole stakeholder community in mid-2021 to find out more about user requirements and obtain feedback. A second workshop in January 2022 will review the first ConOps document, followed by a third in July 2022 to provide final input. “We need to get a picture of the demand,” explains Henk Hof. “There are clear developments in the commercial space category – for example states building spaceports and planning launches such as the UK, Italy and Sweden. It is also possible to estimate super and hypersonic user requirements based on US developments like boom supersonic. The category where there is most uncertainty is high altitude platform systems (HAPS) which features all kinds of platforms with the ability to stay aloft for weeks or even months at a time.” ECHO has embarked on a series of interviews targeting specific companies to find out more about the performance characteristics of these airspace users.


The airspace boundary is another area of discussion, with some industry observers calling for an upper boundary as high as the Kármán line used to delineate the edge of space 100km above the ground. As passenger-carrying hypersonic aircraft are planned to operate in sub-orbital airspace, it is important they are included within the scope of higher airspace ConOps. The lower boundary meanwhile is part of a wider debate about the role of the EUROCONTROL Network Manager (NM) – currently responsible for traffic flow management below FL600 – and higher airspace management services. For example, NM manages the allocation of transponder codes and radio frequencies on behalf of all airspace users and collaborates with military interests to support flexible use of airspace. Henk Hof says adopting a pan-European approach to higher airspace traffic management is central to Europe’s ATM architecture and will allow people to gravitate towards the kind of structure that has made NM a success story.


Both NATO and EDA provide regular input into ECHO as part of efforts to define military requirements. Civil-military collaboration is a precondition for safe and efficient flight operations and this is likely to be supported by information sharing and collaborative decision-making processes. New entrants such as high-altitude platforms add to this complexity by performing both civil and military missions, while experience gained during the Google Loon trials shows these slow-moving craft can operate as low as FL550 depending on meteorological conditions. While still higher than most commercial traffic, this overlaps with some business jets and military craft. “We want to see the airspace as a continuum, unsegregated vertically as well as horizontally, with equal access for all users,” says Henk Hof. 

All aboard

Involving the HAPS community is central to the process of defining airspace requirements and HAPS developers Airbus and Thales Alenia Space are among ECHO industry partners providing input to the project. Under current procedures, airspace is reserved on a temporary basis to enable new operators to access controlled airspace while safeguarding existing users. “For the short term, we see no big changes,” says Hof. “Some new entrants can collaborate together in reserved airspace, for example taking advantage of unmanned traffic management (UTM) technology and working together to avoid collisions. The reserved airspace can also move according to demand.” Other ECHO consortium partners include air navigation service providers (ANSPs), regulators and research agencies.


In the medium- and long-term, large-scale automation of the exchange of data between all actors is necessary to reach the integration phase of higher airspace operations. This anticipates the embedded use of Artificial Intelligence (AI) within a data-rich and cyber-secure connected ecosystem. Establishing an initial ConOps will encourage future airspace users to begin testing some of these systems and start defining the technologies they can deploy on their platforms. “We can see higher airspace acting as an incubator for early implementation of concepts still under development. There are ideas we are working on in ICAO that are hard to introduce with older generation aircraft,” says Henk Hof. “We first need to establish a European view on how we want to organise high airspace, documented by ECHO. This time next year we will be much more informed, and we can take this to ICAO and use it to help define what is needed from ICAO.” With the current procedures likely to remain in place for at least the next five years, the industry has some time to adapt and develop the solutions necessary for future growth.

(SOURCE: Eurocontrol Skyways magazine)

This project has received funding from the SESAR Joint Undertaking under the European Union's Horizon 2020 research and innovation programme under grant agreement No 892928.

ECHO Partners: Airbus UTM (Airbus Operations SL), CIRA, DASSAULT AVIATION, the DLR, the DSNA, ENAC (Italian NAA), ENAV, EUROCONTROL, ONERA and THALES Alenia Space.