A project funded by the European Defence Agency (EDA) has shown that unmanned aircraft can navigate reliably over land without satellite signals, a step towards drones operating safely when satellite signals are disrupted, jammed or denied.
The trials took place within the Unmanned Aircraft Systems
Single European Sky eXperimental Integration (USESXI) project, during the 2026 edition of the Robotic Experimentation and Prototyping using Maritime Unmanned Systems (REPMUS) exercise. Held in September in the Troia area of Portugal, South of Lisbon, they were part of the search for a resilient positioning, navigation and timing (PNT) solution for
unmanned aircraft systems (UAS) when Global Navigation Satellite Systems (GNSS) are unavailable, degraded or subject to interference.
USESXI is a €1.2 million project running for four years until 2028, carried out by Spain’s
GMV and
Indra. Its navigation system, AIRSENSE, uses sensors and artificial intelligence to understand the environment and maintain positioning without relying on satellites.
The exercise tested how well the system captures images, sends data and keeps its sensors in sync, and whether it could support flights beyond and communications visual line of sight. The aircraft flew more than 100 kilometres from the ground control station and reached an altitude of 2,100 metres. A key achievement was running the image-based navigation software on board the aircraft in real time, rather than processing the data after the flight or on the ground station, which would be data-link dependant, and hence a fragility in today’s demanding frontline scenarios.
Commercially available drone used
The system performed well over land, staying close to the aircraft’s true position without satellite signals and showing that combining several navigation sources with advanced algorithms can provide a reliable position even when satellite navigation cannot be trusted or is unavailable.
Over the sea, however, the system was less effective because the sensor-based software had too few landmarks to recognise. EDA will now focus on land operations, in line with lessons learned from current conflicts, so this limitation does not affect the project’s priorities.
The system was tested in realistic operational conditions on a commercially available drone already in service with the Spanish Army. The next step is to develop it into a complete system that meets the required standards and is ready for operational use.
By funding projects such as USESXI, EDA contributes to more resilient autonomous systems, which are increasingly relevant for surveillance, infrastructure protection and emergency response.
These results show that, with EDA support, European industry can develop advanced navigation technologies that are approaching practical use. Such technologies could also help strengthen the resilience of military operations. EDA has co-organised REPMUS since 2024, and the system will be tested again at the 2027 exercise.