Ryosuke Shibasaki, Center for Spatial Information Science, The University of Tokyo, Japan

摘要

Standards are being developed to specify the performance of fault monitors needed to ensure the integrity of LAAS when used for CAT Illb autoland operations. This paperderives fault monitor Pm(} limits based on three concepts: 1) integrity of vertical NSE (VPL concept), 2) risk of unsafe landing for the "limit case" of faulted NSE and 3) risk of unsafe landing for "rare faulted" NSE, The first concept applies only to vertical NSE, while the second and third concepts consider the safety of the longitudinal touchdown point including the aircraft FTE, Performance of fault monitors depends on the type of fault (and tosome extent so do the Pm(j limits). Therefore, the paper addresses faults due to either a single reference receiveror a single satellite. For each type of fault the Pmcj limits are compared to provide insight regarding which requirements concept gives the most restrictive limit. Forsingle reference receiver faults, the Pm(j limits based on VPL and the limit case are found to be comparable.However, for single satellite faults, the VPL-based Pm(i limit is significantly more restrictive. For either type offault, the Pmd limit based on rare faulted NSE is not restrictive in comparison to the other two limits. Compliance with these Pmci limits is illustrated for representative fault monitor performance. Such monitor performance meets the less restrictive Pmcj limit based on the limit case concept with margin for both types of faults. However, detailed performance assessment of specific LAAS monitors for CAT Illb (especiallyconsidering the short time-to-alert of 2 s) remains to be completed