What does BUBBLES intend to do?

BUBBLES is a project targeting the formulation and validation of a concept of separation management for UAS in the U-space.

How are we going to get it?

BUBBLES will develop Artificial Intelligence (AI) based algorithms to compute the collision risk of UAS leading to separation minima and methods so that a Target Level of Safety (TLS) stated in terms of overall probability of collision can be defined and maintained.

These algorithms will be applied to a set of generic ConOps for UAS operations defined by BUBBLES, detailed enough to cover most of the envisaged applications, but generic enough not to be linked to any particular one. They will be classified in terms of risk using the SORA methodology.

These separation minima and methods will be assigned to the ConOps using AI techniques, leading to the definition of a set of generic OSEDs from which safety and performance requirements for the CNS systems will be derived applying a performance based approach.


Towards greater safety and efficiency

Formulate and validate a concept for “Separation Management” in the U-space, defining the basic blocks from which this service will be built and describing how they must be assembled and operated.


  • Formulate and refine a concept of a U-space Separation Management service.
  • Identify and classify on a risk basis a set of generic ConOps for UAS operations.
  • Develop and validate separation minima and methods for UAS.
  • Define a set of generic OSEDs and a procedure to assign one of them to a given ConOps.


  • Draft RxP for CNS , covering operational performance, dependability and security.
  • Draft guidelines and SPR for the AI based systems issuing separation instructions.
  • Develop and validate methods for assessing the compliance with the previous requirements.
  • Draft/update SPR and INTEROP for the U-space services needed by BUBBLES.


  • Contribute to promote the public embracement of UAS and their applications by making the stakeholders and general public aware of the safety levels attained through the Separation Management Service.


BUBBLES will define U-space services enabling the safe and efficient operation of large numbers of drones without adversely affecting manned aviation.

The development of the technology, procedures and training have led to a very low rate of accidents in manned aviation (below 3 per million departures), as well as those of incidents. The concept of Performance Based CNS, first introduced by the ICAO for PBN in 1998, has significantly contributed to transform aviation in the safest massive transport system while supporting an exponential increment in the number of flights.
On the contrary, the contribution of the UAS equipment to events where safety is compromised is, by large, bigger. This difference is due to the fact that Air Traffic Services (ATS) and the systems they rely on are very mature and safe (indeed, EASA reported in 2019 a Separation Minima Infringement Rate below 30/100,000 flight hours). However, U-space services, specially the advanced (U3) ones, are still being defined. Therefore, the improvent of UAS operation safety and efficiency by introducing new advanced U-space services is a must, especially taking into account the expected number of UAS flying in the Very Low Level (VLL) within the Single European Sky – SES (more than 450,000 according to the SESAR drone Outlook).
BUBBLES represents a step forward in the definition of the U-space. BUBBLES combines new blocks along with others already defined by the U-space to assemble a concept for a U-space Separation Management service contributing to increase the safety and efficiency in the VLL. BUBBLES explicitly copes with the effect of the operation of UAS on the safety of manned aviation.

  • BUBBLES will formulate and validate the concept of a new U3 (advanced) U-space Separation Management service providing and maintaining separation minima between UAS and between them and manned aircrafts and fixed obstacles.

  • BUBBLES will extend the concept of Performance Based Navigation, Communication and Surveillance to the UAS, thus allowing them to fly closer even over high risk areas and within VLL volumes shared with manned aircrafts by adopting appropriate mitigation measures.

  • BUBBLES will show to the general public and authorities how the concept of the U-Space Separation Management service leads to operational safety levels comparable to those achieved by the manned aviation, thus contributing to the public acceptance of UAS.