Assessment of GPS/EGNOS positioning integrity and accuracy at a small airfield using a local protection level model

Abstract

The article analysed the possibility of using the European Geostationary Navigation Overlay Service (EGNOS) system as an extension of GNSS systems in landing procedures at small airports and landing sites without classic ground infrastructure. The aim of the study was to assess the positioning accuracy and integrity protection levels (HPL and VPL) in selected Global Navigation Satellite System (GNSS) signal reception configurations, including autonomous GPS, multi-system systems (GPS/GLONASS, GPS/Galileo/BeiDou, Full GNSS) and Satellite-Based Augmentation System (SBAS) modes: EGNOS non-precision approach (NPA) and EGNOS precision approach (PA). The measurements were carried out using a Septentrio PolaRx5e GNSS surveying receiver located at the Gryźliny landing site (EPGR). The observational data were processed using the Septentrio PP-SDK software and then subjected to statistical and graphical analysis, taking into account positioning parameters, such as position error distribution over time, horizontal and vertical accuracy (HPE, VPE), geometric coefficients (PDOP), and confidence levels (HPL, VPL). In addition, the article includes an analysis of cumulative distribution functions (CDF), Stanford plots, relative rHPL and rVPL indicators, and the Local Protection Level Model (LPLM) developed as part of this work. The results obtained clearly show that the configurations supported by the EGNOS sys - tem significantly improve positioning accuracy and provide greater stability compared to autonomous modes. The EGNOS system is therefore a reliable and effective tool for implementing the GNSS-based approach procedures at small airports, in accordance with the ICAO standards for performance-based navigation.