On August 12, Air China operated the first regular international passenger flight of the COMAC C919, linking Beijing Capital International Airport with Ulaanbaatar, Mongolia. The daily service, numbered CA723/CA724, marks a symbolic breakthrough for China's aviation industry: the single-aisle jet, which entered commercial service with China Eastern in May 2023, had previously flown only on domestic routes. The choice of Ulaanbaatar is strategic—a short, two-hour hop that minimizes operational risk while demonstrating the aircraft's ability to cross borders in routine service, not just in demonstration or ferry flights. On paper, the C919 sits squarely in the heart of the global narrowbody market, competing with the Airbus A320neo and Boeing 737 MAX. With a capacity of 158–192 seats and a range of 4,075–5,555 km depending on version, it is designed for high-density Asian routes. However, the industrial reality lags far behind the ambition. COMAC delivered only 15 C919s in 2025, a fraction of the 75-unit target, and just three in the first quarter of 2026. The order book exceeds 1,000 units, but production ramp-up remains constrained by supply chain issues. Analysts like Rob Morris of Ascend by Cirium note that COMAC's development and production pace is simply too slow to challenge Airbus and Boeing in the near term, and that the manufacturer must also provide 24/7 support to match the dispatch reliability of established types. Beyond production, the C919's dependence on Western suppliers—notably CFM International LEAP-1C engines and avionics—exposes the program to geopolitical and supply chain risks. Certification is another hurdle: the aircraft holds a Chinese type certificate from the CAAC but lacks EASA and FAA validation. EASA has conducted test flights in Shanghai, but its executive director estimated in 2025 that European certification could take three to six years. For aviation students, this case study illustrates the gap between a successful first flight and a mature, globally competitive aircraft program—a lesson in the complexities of certification, supply chains, and after-sales support that define the real world of commercial aviation.