Recently, the flight test team of the Civil Aviation Administration of China (CAAC) Shanghai Certification Center has successfully carried out multiple RNP AR certification flight tests for the C909 aircraft at various test sites. These flight tests were systematically conducted in three distinct phases: plain, plateau, and high-plateau environments. This was done to comprehensively verify the C909's core performance in high-precision navigation and its operational capabilities in complex terrain. RNP AR represents a cutting-edge precision navigation technology in civil aviation that operates independently of ground-based navigation aids. It enables aircraft to execute precision approaches, effectively circumvent obstacles at high-altitude airports, and significantly reduce flight delays and diversions. The C909, originally designated as the ARJ21, is a domestically developed 90-seat short-to-medium-range turboprop regional jet. By June 2026, a total of 186 C909 aircraft have been delivered, representing 70% of the domestic regional jet fleet. This flight test offers vital support for the C909's subsequent airworthiness certification and the expansion of its operational routes.