Session B2b: Autonomous Navigation and Safety-Critical Applications

Improving Navigation Resilience for Civil Aviation
Okuary Osechas, ZHAW; and Gary McGraw, Genova Tech
Location: Beacon B

INTRODUCTION
The landscape of Radio Frequency Interference (RFI) on Global Navigation Satellite Systems (GNSS) is changing rapidly. By some accounts (OPSGROUP, 2024), characteristics of both jammers and spoofers change as frequently as every six weeks; by comparison, the update of an aviation standard can take between five and ten years from initial proposal to final publication.
Neither jamming nor spoofing should, under normal circumstances, unacceptably impact aviation safety. Aircraft systems are designed with redundancy in mind and operations provide ample margin for in normal operations. However, the effects of jamming and spoofing typically result in increased workload for crews, which has a consequence of reducing safety margins, particularly when other difficult conditions occur, such poor weather or heavy traffic. Jamming and spoofing may also result in a loss of airspace capacity.
BACKGROUND
The two phenomena of jamming and spoofing are often conflated as “interference”. There are, however, significant differences in how they impact aviation users. Jamming is often portrayed as being simpler, suggesting that potential solutions may be easier to deploy. At the same time, wide- spread spoofing is relatively new and is seen as mysterious and more threatening. A recent safety bulletin by the European Union Aviation Safety Agency (EASA) details the risks and threats to civilian aircraft, stemming from “GNSS Outages and Alterations” (EASA, 2024).
One potential approach to mitigating the impact of RFI is to complement GNSS sensors with other terrestrial capabilities. A wide range of technological options can potentially provide sufficient navigation performance to adequately complement GNSS in Performance Based Navigation (PBN) operations, but they all have different benefits and drawbacks. A thorough review of these alternatives includes not only a fairly comprehensive list of viable systems, but also a methodology for evaluating their performance.
Another viable approach is to harden on-board GNSS receivers on civilian aircraft. Here the evaluation metrics may be more straight-forward: navigation performance and implementation cost/complexity, but the technological avenues are different from the proposals above. GNSS receivers can be strengthened at various places in the processing chain, from the antenna, through the radio front end, all the way to monitoring navigation observables. Some of these methods require changes in software, while others require tweaks in the hardware, all the way to fundamentally new architectures, wiring and antenna layouts; note that these latter methods could end up being prohibitively expensive in the current business environment, but are still worthwhile writing down for future reference.
IMPACT ON OPERATIONS
The paper describes the impact of jamming and spoofing on conventional, mainline aircraft. In addition, it explores potential solutions that would augment or complement GNSS, as well as protecting airborne receivers from the effects of RFI. Keeping in mind that such efforts need to be coordinated with a broader effort of protecting spectrum, toughening receivers and augmenting services (PTA). The notion being that if these PTA measures are strong enough, the incentive to jam or spoof GNSS will decrease over time.
CALL FOR ACTION
The paper closes with a call to action, addressing the various stakeholders involved in keeping
aviation safe and efficient, with integrative thinking across different stakeholders a key component to solve the challenge. The call to action includes recommendations for the near, medium and long term. It is important to note that perfect resilience will yield little to no benefits in efficiency, if any measures are taken in isolation: the benefits of an improved navigation system will only translate into reduced separation if reliable collision risk and wake-encounter models exist.
REFERENCES
EASA (2024), “Safety Information Bulletin 2022-02R3: Global Navigation Satellite System Outage and Alterations Leading to Communication / Navigation / Surveillance Degradation”.
OPSGROUP (2024), “GPS Spoofing, Final Report of the GPS Spoofing WorkGroup”, https://ops.group/blog/gps-spoofing-final-report/.