Analysis of GNSS Disruptions in European Airspace
Michael Felux, Benoit Figuet, Manuel Waltert, Patric Fol, Zurich University of Applied Sciences; Martin Strohmeier, Armasuisse; Xavier Olive, ONERA – DTIS, Université de Toulouse
Location: Seaview Ballroom (1st Floor)
Date/Time: Wednesday, Jan. 25, 4:00 p.m.
Air traffic today is mainly relying on Global Navigation Satellite Systems (GNSS) for accurate and reliable positioning and guidance in most phases of flight, including for departure, cruise flight and during arrivals. For approach and landing, space-based and ground-based augmentation systems (SBAS / GBAS) provide corrections for the GNSS signals yielding improved accuracy. With the additionally provided integrity parameters, residual navigation errors can be safely bounded, and the augmented GNSS position information can be used for precision approach guidance. Currently, SBAS supports instrument approaches down to the category CAT-I minimum, i.e., down to 200 ft above ground, while GBAS can be used to the CAT-II minimum, i.e., down to 100 ft above ground, and will soon be able to also provide guidance under CAT-III conditions, i.e., without visibility restrictions. As GNSS is currently the only means in aeronautical navigation to provide integrity along with the position solution, it is the only navigation system supporting procedures with a Required Navigation Performance (RNP). Furthermore, GNSS feeds a variety of other aircraft systems, such as for example Terrain Awareness Warning Systems (TAWS) and surveillance functions of the aircraft. The Automatic Dependent Surveillance Broadcast (ADS-B) transmits aircraft position information along with integrity parameters regarding the estimated position uncertainty (EPU) and position source integrity level (SIL). These parameters decrease when GNSS-based navigation is disturbed or interrupted and are thus good indicators for regions where aircraft are subject to Radio Frequency Interference (RFI).
Since the beginning of the Ukraine conflict in early 2022, there were numerous reports and documented instances where air traffic over Europe was experiencing GNSS disruptions. These incidents were mainly observed over Finland, the Baltic states, the Russian exclave Kaliningrad, Romania and Bulgaria. While air traffic being subject to RFI is not a new phenomenon, the extent of disturbances observed over the past months deserves a more detailed analysis. Most large commercial aircraft do not solely rely on GNSS as their only navigation system, but are equipped with high-grade inertial reference systems, other radio navigation equipment, or a combination thereof. But even for those aircraft loss of GNSS still causes nuisance warnings in the flight deck and thus increases the workload of pilots. It furthermore prevents all navigation procedures requiring GNSS from being used. Besides that, the impact of RFI on GNSS on smaller and less-well equipped aircraft may be more severe.
In this paper we identify the RFI hotspots in Europe, their timely evolution over the months January to September 2022, and assess their impact on air traffic. For the analysis, we base the identification of RFI on the ADS-B parameters. The ADS-B data used was obtained from the OpenSky Network, a crowd-sourced network of ADS-B receivers with good coverage across Europe. We analyze the number and share of affected aircraft of the total amount of the civil air traffic passing through the regions. Together with a distribution of aircraft types and equipage information, this study allows for more detailed impact assessments on air traffic, regarding for instance the potential need of ATC support of aircraft and impact on collision risks.
Finally, the paper discusses the potential impact of these jamming events on global and regional air navigation strategies for the evolution of aeronautical navigation systems. It further assesses the required ground and/or space-based navigation infrastructure needs in order to support safe and efficient air traffic operations in the future.