Abstract—The unpredictable ionospheric delay error remains the primary constraint on Ground-Based Augmentation System (GBAS) availability for Category II/III (CAT-II/III) approaches, posing a dominant challenge to safety and precision. This review evaluates GBAS Approach Service Type D/E (GAST-D/E) achievability, equivalent to CAT-II-III), by mitigating ionospheric errors, drawing on recent R&D advancements. Three key findings emerge: (1) Real-time ionospheric prediction enhances GAST-D availability by up to 30% in mid-latitude regions but proves inadequate near the equator due to severe gradient variability. (2) Dual-frequency multi-constellation methods (GPS L1/L5 + Galileo E1/E5) reduce residual ionospheric errors by 70–90%, demonstrating GAST-E compliance in simulation studies. (3) AI-driven models show potential for storm forecasting but require operational validation in GBAS environments. While current single-frequency GBAS meets GAST-C standards globally, achieving higher performances necessitates hybrid strategies integrating real-time monitoring, multi-frequency signals, and region-specific threat models. The paper further identifies regulatory gaps in certifying these advanced methods and calls for industry-aviation authority collaboration to standardize solutions.

Keywords—Global Navigation Satellite Systems (GNSS), GPS, Galileo, Ground-Based Augmentation System (GBAS), GBAS Landing System (GLS), GAST-D/F

Cite: Ahmad Alhosban and Tibor Farkas, “Analyzing Ionosphere Delay Error in GBAS Landing System (GLS) Type D/F−Systematic and Comprehensive Review," Journal of Communications, vol. 20, no. 5, pp. 515-522, 2025.


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