Performance evaluation of Category III precision landing using airport pseudolites

Further improvements are needed to fulfill the growing demand requirements for a Category III precision landing system architecture, which is completely contained on the airport property. The integrity of an on-airport local area augmentation system can be seriously threatened by failures of the DGPS systems even for a very short time. A pair of airport pseudolites (APLs) will be unable to maintain phase lock and provide navigation solution, if a satellite failure occurs during the navigation solution process. An autonomous system of five airport pseudolites can be used to perform Category III precision landing. The differential carrier phase among them can provide four pairs of independent observable measurements, which are sufficient to solve for integer ambiguity and thus they are able to provide a navigation solution. To insure integrity with a probability of misdetection of 0.001 a system of six airport pseudolites is analyzed and simulated in this paper.