Image: Real time display of aircraft being spoofed courtesy SKAI Data Services
What’s new: Dr. Okuary Osechas and Dr. Gary McGraw continue to refine their December paper that examined navigation systems needed in aviation to complement GPS/GNSS in order to achieve Performance-Based Navigation (PBN), the aviation community’s goal to maximizes air traffic efficiency and safety
Why it’s important: This paper builds upon one released in December and was presented at ION’s International Technical Meeting in January. It:
- Adds discussion about Complementary PNT (CPNT) for Advanced Air Mobility (AAM).
- The recommendations for CPNT for AAM deviated somewhat from the recommendations made for conventional air transport in that eDME does not seem appropriate for AAM applications, primarily due spectrum compatibility issues. Also in terms of ground station siting and aircraft integration.
- Instead of eDME the paper suggests commercial pseudolites like Locata might have a role.
- Also, PNT from 5G might be viable.
What else to know: Our view (in case you had not already guessed) is that reinforcing aviation’s use of GPS with at one or more additional nav sources integrated aircraft systems is inevitable. The longer the aviation community takes to decide on and implement those systems, the longer the danger to life and property. And the greater the chance the changes will be made in a hurry, be more difficult, and more expensive.
Terrestrial Navigation Alternatives to Support PBN for Current and Future Aviation*
Okuary Osechas, Zurich University of Applied Sciences (ZHAW)
Gary McGraw, PNT Consultant–Genova Technologies
BIOGRAPHY
Dr. Okuary Osechas is a researcher at the Zurich University of Applied Sciences. He received a PhD from Tufts University, where he was sponsored by the FAA to develop new concepts for integrity monitoring in GBAS. He worked at the German Aerospace Center, where he led efforts to make air traffic more resilient to GNSS RFI. He leads the standardization Working Group 85 at EUROCAE, which together with RTCA Special Committee 227, maintains the RNP standards. He is an Associate Editor with IEEE Transactions on Aerospace and Electronic Systems.
Dr. Gary McGraw is a PNT consultant with Genova Technologies. He is retired from Collins Aerospace (formerly Rockwell Collins), where he was instrumental in the development of several significant PNT technologies for civil aviation and military applications. He is currently involved in research in Complementary PNT technologies and supporting development of DFMC GBAS. Dr. McGraw received his PhD from UCLA. He is a Fellow of the ION, Kepler Award recipient, and an Associate Editor for NAVIGATION.
ABSTRACT
This paper recommends technologies for aviation authorities to consider to make Performance Based Navigation (PBN) services more resilient to GNSS Radio Frequency Interference (RFI) and other threats. Combining toughened GNSS with terrestrial Complementary Positioning, Navigation and Timing (CPNT) will enable seamless PBN services during GNSS degradation or loss, yielding many benefits to efficiency and airspace utilization, and ultimately for safety. The analysis here considers diverse, viable PNT alternatives to GNSS for both Conventional Air Transport (CAT) and Advanced Air Mobility (AAM) aviation and proposes performance criteria by which to evaluate them. Applying these criteria to the systems under consideration results in a set of three technologies with the most promise for development and implementation for CAT: Enhanced Distance Measuring Equipment (eDME), Enhanced Long Range Navigation (eLORAN), and L-Band Digital Aviation Communication System- Navigation (LDACS-Nav). For AAM the analysis indicates a different mix: eLORAN, LDACS-Nav, and possible developments
in 5G Cellular, Commercial Pseudolites and new AAM/drone data links. This work can also inform national decision makers who must take a view broader than aviation and reinforce their PNT architectures to serve other modes of transportation, critical infrastructure, and essential applications.
Osechas, Okuary, McGraw, Gary, “Terrestrial Navigation Alternatives to Support PBN for Current and Future Aviation,” Proceedings of the 2025 International Technical Meeting of The Institute of Navigation, Long Beach, California, January 2025, pp. 253-267. https://doi.org/10.33012/2025.19970
