From the successful first flight in 2017 to the model certificate in 2022, the domestic large aircraft C919 has completed the most important "big test" before being put into market operation, to show that its safety and reliability fully meet the requirements of market operation, and then start a new journey of marketization and industrialization. In the past five years, C919 flew all over the world, withstanding the severe test of ice, snow, strong wind, high temperature and severe cold, and challenged the limit test flight of full aircraft static test, stall, flutter, maximum braking energy, minimum ground speed, etc., and handed over a complete "answer sheet"; In the past five years, the C919 overcame the complicated influence of the COVID-19, built a bridge through mountains and rivers, determined to innovate independently, open up and cooperate, and overcame all difficulties with full tenacity; In the past five years, C919 has driven the construction of scientific and technological innovation and high-end intelligent manufacturing industry ecology centering on the aviation industry from one product to one platform; In the past five years, the "big airplane people" gathered by C919 have brought the dream of "Chinese people must have their own big airplane" into reality. They are full of the ambition of aviation power, dare to climb the peak, dare to fight and dare to fight, and build the talent foundation of domestic big airplane industry. The successful "answer sheet" of the safety "big exam" "obtaining the model certificate, which is often referred to as the airworthiness certificate, is the end of the C919" graduation exam "and the prelude to opening the commercial operation." Jie Yuwen, deputy director of CAAC Shanghai Certification Center and head of C919 large passenger aircraft model review team, said. In September, the Civil Aviation Administration of China issued the model certificate to the large domestic aircraft C919, which marked that it had a qualification certificate for entering the market and obtained the "ticket" for commercial operation. What is the model certificate? Why should commercial aircraft be put on the market after successful certification? According to the Civil Aviation Law of the People's Republic of China and the Airworthiness Regulations of the People's Republic of China, civil aviation products must be airworthy before entering the market. The Civil Aviation Administration of China is responsible for the airworthiness certification of civil aviation products. It requires that all civil aircraft must obtain a type certificate before entering the market to show that an aircraft meets the requirements of relevant airworthiness regulations and is in a safe, reliable and airworthy state. Jieyuwen introduced that CAAC formulated and promulgated airworthiness regulations and standards to conduct airworthiness certification, supervision, inspection and management of civil aviation product design and manufacturing. China's airworthiness regulations, including systems, standards and procedures, are in line with international standards. How to comprehensively verify the safety and reliability of commercial aircraft? During the approval process, it is necessary to carry out a series of calculation and analysis, implement a series of equipment identification, pass a series of test flights, complete a series of technical reports, and comprehensively and fully prove that the aircraft can meet the requirements of safe and reliable operation. "Just like employees who want to complete the qualification examination and work with certificates, a commercial aircraft needs to have a 'work license' before it is put on the market, and the model certificate is the most important one." Jieyuwen said. C919 adopts the new generation of high bypass ratio engine, supercritical wing and other advanced aerodynamic design, fly by wire flight control, integrated avionics and other airborne systems. In the process of airworthiness certification, it is necessary to fully implement the application of these new technologies and functions