Advancing U-space implementation through a collaborative approach to simulation

Patrick Amar & Miguel Vilaplana

Patrick Amar, Head of Drones programme at EUROCONTROL and Miguel Vilaplana, Head of UTM at AIRBUS

A joint Airbus/EUROCONTROL U-space simulation service prototype is giving States, regulators, standards bodies and industry a unique view of the risks and effectiveness of different procedures required for implementing U-space airspaces in Europe.

It has been over a year since the European Union’s U-space regulation EASA 2021/664 was published, allowing Member States to identify airspace areas where drones can fly increasingly complex, multiple operations – beyond visual line of sight, over people, autonomously and at night – supported by UAS traffic management (UTM) systems run by certified U-space service providers (USSPs). But by the start of 2024, no such U-space areas had been designated.

One of the main challenges has been for States to ensure that an entirely new type of digital air traffic management system will meet the required safety standards. As part of the regulation, States must conduct airspace assessments to prove that the U-space system will be able to manage increasingly complex drone operations within an acceptable level of air and ground risk.

For the past few years, EUROCONTROL has been supporting States in this work . More recently, the Agency has been working with Airbus to optimise this task by running realistic airspace simulations.

“Our work together started with a joint realisation that simulation is a key enabler of the development and deployment of U-space,” said Miguel Vilaplana, Head of UTM at Airbus. “We didn’t start with a blank sheet of paper; Airbus has been working with the Federal Aviation Administration and other partners on UTM in the USA for many years and we have been contributing to key U-space projects in SESAR.”

“We ran a pilot project in Riga and then continued to develop the programme with Spain and Switzerland,” said Patrick Amar, Head of Drones Programme at EUROCONTROL. “The programme is part of the Innovation Hub and one of our roles is to advise Member States on how to implement the regulation.”

The airspace simulator is an important tool in this process and provides a realistic representation of the U-space ecosystem. It allows the user to simulate drones and traditional aircraft traffic in overlapping airspace, based on assumptions of demand. It also allows users to simulate other U-space services such as strategic deconfliction and flight authorisation, and to validate standards and the interfaces between stakeholders.

The simulator has proved particularly useful in assessing the air risk – potential drone-to-drone and crewed aircraft-to-drone collisions – which is difficult to assess in any other way. It generates data to validate and verify concepts of operation and interoperability between different elements of the proposed system by simulating drone and traditional crewed aircraft traffic interactions, tracking the separation between vehicles.

“We run thousands of flight hours of data, with stochasticity injected in when and where the operations take place, as well as in the position of the actual vehicles during flight, impacting the conformance of each vehicle to its authorised operational intent,” said Miguel Vilaplana. “This data is then processed to identify the risk of collision and identify where constraints need to be implemented and the subsequent impact of those constraints.”

One of EUROCONTROL’s key roles in the partnership is to capture the needs of Member States in granular detail. “We gather this information and then interpret it in a way so it can be translated into formats useable by the simulator,” said Patrick Amar. “We have to stay close to the users to make sure we are providing them with the exact simulations they need, reflecting their operational constraints.”

The initial use cases of the simulation capability focused on quantifying the impact of strategic deconfliction on safety, but other functions have also been tested, including validating demand-capacity balancing and conformance monitoring services and exploring the impact of dynamic airspace reconfiguration to accommodate traditional crewed traffic in the vicinity of airports.

“This year we will also report back to the European Aviation Safety Agency (EASA) with a review of its implementation plans and some advice on how the regulations might be improved,” said Patrick Amar. “We are in a process of continual development – making sure the simulator has the most up-to-date and realistic data on the vehicles flying.”

While these simulations are specifically targeted at supporting regulators and Member States for airspace risk assessments, other stakeholders are also benefiting from the availability of the service. It has been used to validate requirements of existing standards, such as the ASTM standard for UTM Service Supplier Interoperability – where a 95% conformance to operational intent needs to be shown. Municipalities can start to understand the implications of airspace constraints on drone traffic density in their cities and how to position future infrastructure such as vertiports. Drone operators and U-space service providers can use this type of simulation to support validation and stress-testing of their systems and services, to confirm that they operate as expected under high-density scenarios.

EUROCONTROL identified that it is a challenge for U-space stakeholders who are not aviation experts to fully understand the impact of drone traffic: the simulator provides a way to quantify and visualise this impact that is easy to understand and to adapt (modify no-fly areas, etc.) facilitating collaboration between CAAs, ANSPs, municipalities and security forces.

And as lower airspace operations multiply with the addition of eVTOL (electric vertical take-off and landing) traffic, the simulator can be progressively enhanced to add new vehicle types and more complex operations. While eVTOL operations are likely to differ from drone operations – with more defined route networks and more interactions with traditional crewed traffic – the core airspace management technologies being validated with the simulator will remain relevant. The simulator has already been used in work with NASA on the Advanced Air Mobility National Campaign to validate concepts of operation around eVTOL operations.

The simulator will also be available to support SESAR and other research projects in areas such as separation management in U-space and its performance, design of flight rules, the implementation of demand capacity balancing, assessment of the performance and behaviour of federated U-space implementations and the value of safety nets, such as aircraft collision avoidance systems.

In the future, the simulator could be run with actual traffic data to verify the consistency of the U-space airspace design and deployed procedures, or to update them as required.

“We will support Member States by ensuring simulations remain as realistic as possible to meet their specific requirements,” said Patrick Amar.

“With these simulations, Airbus and EUROCONTROL can together help open the airspace to new entrants while protecting the growth and sustainability of traditional commercial air transport," said Miguel Vilaplana. “We have a shared vision.”

Some conclusions of the Riga U-space simulation exercise

There is a strong indication that strategic deconfliction, as applied in the U-space simulator work for Riga, could have significant benefits in terms of safety.

This is one of the conclusions of a study which specifically looked at different scenarios for airspace constraints in Riga, and their impact on future drone operations. While the nature of the different constraints is quite specific to the city, several conclusions can be drawn that extend beyond that one use case.

Three scenarios were simulated across a range of demand levels in the Riga work:

  • a baseline in which no airspace restrictions are in place;
  • a scenario in which a small number of airspace restrictions are in place associated with air risk, and
  • a scenario in which a larger number of airspace restrictions are in place associated with both air risk and ground risk.

“The results presented suggest that the probability of a mid-air collision (MAC) increases with increasingly complex airspace restrictions, but that the effectiveness of strategic deconfliction to reduce the probability of MAC remains approximately constant,” according to the research findings Simulating Safety and Efficiency Impacts of Airspace Constraints in U-Space Airspace .

“Hotspot maps show high traffic and loss of separation density around UAS demand origins and delivery locations for all unmitigated scenarios simulated. However, when airspace restrictions are added, traffic and loss of separation density increases significantly on the edges of some restrictions.”

The results show an approximately constant reduction in MAC per flight hour when applying strategic deconfliction – of 99.2%. This suggests that strategic deconfliction based on volumetric intent, as described by the ASTM UTM Standard, could be effective at reducing risk of collision in constrained airspace.

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