Applying Space Weather Information to GBAS: A Concept for Improved Availability

Kurzfassung

This paper proposes a novel concept to improve Ground-Based Augmentation System (GBAS) availability by integrating near-real-time Space Weather information from the Ionosphere Monitoring and Prediction Center (IMPC) into the GBAS Approach Service Types (GAST) C and E (GAST-C and GAST-E) as part of the In2Action project from the German Aerospace Center (DLR). The methodology uses IMPC products, including the Rate of TEC Index (ROTI), the Disturbance Ionospheric Index Spatial Gradients (DIXSG), a Wave Front Detector (WFD), and a near-real-time sigma_vig estimate to classify the ionospheric state. For GAST C, the concept replaces static, worst-case sigma_vig inflation with near-real-time estimates when quiet conditions are verified. For GAST-E, external information is used to adaptively adjust the prior probability of anomalous gradients in the airborne dual-frequency monitor. The concept was tested using flight data from a DLR campaign in Germany. Results for GAST-C show that near-real-time sigma_vig integration avoids the excessive protection level inflation required by regional ionospheric threat models like CONUS or Brazil, while exhibiting smaller differences for the German threat model. For GAST-E, the approach achieved a 20% reduction in the ionospheric monitor test statistic under nominal conditions, directly increasing the margin against false alerts. While issues such as non-ionospheric data contamination and certification remain, this work demonstrates that a synergy between Space Weather monitoring and GBAS can significantly reduce operational conservatism without compromising civil aviation integrity requirements.