Development of a Ground Subsystem Prototype for Ground-Based Augmentation System (GBAS) Approach Service Type D (GAST-D) and the Evaluation of Its Performance in a Low Magnetic Latitude Region

A ground-based augmentation system (GBAS) is a navigation system using global navigation satellite system (GNSS) that enables precision approaches and landing for aircraft. In May 2010, the International Civil Aviation Organization (ICAO) Navigation Systems Panel (NSP) working group completed development baseline standards and recommended practices (SARPs) for GBAS ground subsystems to support GBAS approach service type D (GAST-D), which refers to Category III precision approach services using the single-frequency L1-C/A signal. The Electronic Navigation Research Institute (ENRI) developed a prototype of the GAST-D ground subsystem to operationally validate the development baseline SARPs. Owing to the fact that ionospheric delays with large spatial gradients represent one of the most significant risks to the integrity of the GAST-D operation, the system was installed in a low magnetic latitude region where plasma bubble causes steep spatial gradients in the ionospheric delay. Preliminary results were reported to the NSP working group before the development baseline SARPs were approved in December 2016 with an expectation that they would go into effect in 2018. Here, we report the development of a prototype for a GAST-D ground subsystem to validate the development baseline SARPs and preliminarily evaluate the system’s performance.