[EN-030] Using SBAS to Enhance GBAS User Availability: Results and Extensions to Enhance Air Traffic Management

This paper describes the application of Space Based Augmentation System (SBAS) corrections and error bounds to improve the availability of Ground Based Augmentation Systems (GBAS). GBAS installations within good SBAS coverage can use the SBAS UDRE and GIVE error bounds to mitigate the most severe integrity threats to GBAS. GBAS systems are limited by their inability to detect severe ionospheric gradients with the required missed-detection probability. A method for using GIVE values to insure the absence of these gradients is described here, and the use of UDRE to mitigate ephemeris and signal-deformation failures is also discussed. Because the techniques used in SBAS monitoring are well known, GBAS installations outside of SBAS coverage can apply the same techniques based upon data from other GNSS reference networks that may already exist or can be built or expanded to serve GBAS. An expansion of an existing network in Australia is proposed here to demonstrate the potential of this approach. Concerns regarding the cost, safety, and certifiability of systems that use external networks that are not themselves certified are addressed.