Integrated DME/INS Alternative PNT System for RNP 1

Birendra Kujur, Samer Khanafseh, Boris Pervan, Valeriu Vitan, Gerhard Berz, Okuary Osechas

Peer Reviewed

Abstract:	This paper proposes an alternative Position, Navigation, and Timing (APNT) system that integrates a tightly coupled Distance Measuring Equipment (DME)/Inertial Navigation System (INS) within a Kalman Filter (KF) architecture. This configuration satisfies the Required Navigation Performance (RNP) 1 criteria for straight-and-level flight across European airspace. While RNP has traditionally been supported by Global Navigation Satellite Systems (GNSS), its expansion into airspaces with tighter requirements continues globally (RTCA SC-227 (2025a), RTCA SC-227 (2025b)). RNP’s standardized framework and benefits—such as increased airspace capacity and precise route guidance—make it an appealing candidate for continued adoption. However, the growing incidence of GNSS jamming and spoofing (Kerns et al. (2014), Kujur et al. (2024)) threatens its reliability. Currently, no standards exist for complete GNSS failure scenarios. As a result, aviation stakeholders are actively exploring resilient APNT solutions as potential GNSS backups (Berz et al. (2013), Vitan et al. (2015), Osechas et al. (2022)). Among terrestrial navigation aids, DME presents a promising foundation for APNT architectures due to its legacy infrastructure and operational robustness (Berz and Saini (2022), Lo et al. (2013),Lo et al. (2013),Lo and Enge (2012b),Vitan and Theißen (2016)). The performance of the multi-DME KF system is first evaluated in a representative scenario. Subsequently, the integrated DME/INS KF system is assessed, including its inertial coasting capability during complete DME signal outages. Results demonstrate that this architecture can achieve position errors with a standard deviation of less than 50 meters. To enhance system integrity, solution separation–based fault detection, identification, and exclusion (FDE) is implemented by running a bank of KFs (Gunning et al. (2019); Tanil et al. (2019)). Protection level results are presented for the integrated DME/INS system, indicating its potential to satisfy RNP 1 integrity requirements. The analysis also considers various grades of Inertial Measurement Units (IMUs) to evaluate the system’s suitability for general aviation.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	1624 - 1646
Cite this article:	Kujur, Birendra, Khanafseh, Samer, Pervan, Boris, Vitan, Valeriu, Berz, Gerhard, Osechas, Okuary, "Integrated DME/INS Alternative PNT System for RNP 1," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 1624-1646. https://doi.org/10.33012/2025.20277
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