Analysis of GBAS Integrity Requirements Based on Single Frequency Beidou Supporting CAT III

GNSS ground-based augmentation systems (GBAS) can be capable of supporting precision approach and landing operations for A/C. The existing GBAS system supports CAT I operation and the GBAS system supporting CAT III operations has been developed. The GBAS requirements for supporting CAT III are more stringent than those for supporting CAT I, especially for integrity. The allocation and derivation of integrity requirements of GBAS system supporting CAT III is difficult to follow the approach of CAT I. The international standard for GBAS systems based on GPS single frequency supporting CAT III has been established. The GBAS supporting CAT III is being actively researched in China, and GBAS technical standard based on Beidou supporting CAT III is in dispute, which makes the development, testing and application of related equipment lack the necessary basis. Therefore, it is necessary to study the allocation and derivation of GBAS system integrity, and carry out top level requirements research on the integrity of Beidou based GBAS system. This paper analyses the integrity requirements of GBAS system based on the single frequency Beidou system supporting CAT III. The integrity requirements of GBAS system supporting CAT III originate from aircraft’s automatic landing requirements. The requirements analysis starts from the landing performance requirements, focusing on the navigation system error (NSE) closely related to GBAS system. Combined with necessary hypothesis, integrity requirements of GBAS system under limit case and malfunction case required by the landing safety are deduced, the ground monitoring probability of missed detection of a ranging domain error due to a ranging source fault is obtained, and a preliminary discussion of airborne guarantee method for integrity is made. This paper provides a valuable reference to establishing top-level requirements of GBAS system based on Beidou system supporting CAT III.