Abstract The RAIM(receiver autonomous integrity monitoring) availability effect in the Asian-Pacific region at non-precision approach(NPA) caused by each GEO satellite is counted using the RAIM availability adjustment method. Results show that the maximum availability differences affected by GEO satellites are 07∶00~08∶00 and 15∶00~16∶00, but the influence of each GEO is different. The orbit control periods of 14∶00~23∶00 for GEO C04 and 00∶00~05∶00 for GEO C05 make system availability lower than 99.9%, mainly caused by the designated position of the two GEO satellites and the regression cycle of MEO satellites. In addition, in order to reveal the availability improved by the new C13, which is an initial operational capability IGSO satellite, availability before and after having the BDS C13 satellite are obtained. It can be seen that the average RAIM availability reaches 99.99% after enabling the C13 satellite.
