Terrestrial Navigation Alternatives to Support PBN for Current and Future Aviation

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.