BEIJING, Jan 13 (AFP) - A Boeing Co (BA.N) 737 MAX made its first passenger flight in China in nearly four years on Friday, marking a major milestone in the U.S. planemaker's attempt to rebuild its business in the world's second-largest aviation market.

The China Southern Airlines Co Ltd (600029.SS) domestic flight from Guangzhou to Zhengzhou departed at 12:45 p.m. (0445 GMT) using a MAX plane, according to flight tracking website FlightRadar24.

The best-selling Boeing model was grounded in March 2019 after fatal crashes in Indonesia and Ethiopia, but returned to service around the world starting in late 2020 after modifications to the aircraft and pilot training.

China is the last major market to resume flying the MAX amid ongoing trade tensions with the United States, and the return comes as domestic travel demand rebounds after it abandoned zero-COVID policies.

Foreign airlines began flying the MAX to China in October 2022, in a sign the first country to ground the model after the crashes was loosening its policies.

China Southern had scheduled a return to commercial service for the 737 MAX in October 2022 but did not use it on the planned flights.

Boeing and China Southern did not immediately respond to a request for comment.

Chinese airlines had 97 of the narrowbody planes before the grounding, according to Cirium data in 2019. China Southern is the biggest Chinese customer for the model, with 50 on order, of which 34 have been delivered.