An Aircraft landing system using Differential GPS (Global Positioning System), such as GBAS (Ground Based Augmentation System), requires high reliability and integrity. It is well known that a satellite failure like the case of 19th satellite problem in 1993 produces large positioning error on GBAS users. Therefore, it is necessary to detect such failures and to alert within the time of TTA (time-to-alert) in order to secure the integrity of GBAS.

This paper describes that the method of the GPS Satellite failure detection in the SQM (Signal Quality Monitor) which we propose to use for GBAS. We also refer to how to determine a threshold and MDE (Minimum Detectable Error) by false detection probability and miss detection probability based on the result of a hardware simulation. Finally, we apply the method to the real signal. As results, it is successfully demonstrated that the MDE calculated by the proposal technique satisfies the acceptable value of the pseudo-range error of a ranging source monitor demanded by the high category GBAS examined now.