A technician examines the appearance of an airplane in Harbin, northeast China's Heilongjiang Province, Feb. 10, 2018. About 50 technicians of Heilongjiang branch of China Southern Airlines are responsible for checking and maintaining airplanes to better cope with the upcoming Spring Festival travel rush. (Xinhua/Wang Kai)

A technician examines the engine of an airplane in Harbin, northeast China's Heilongjiang Province, Feb. 10, 2018. About 50 technicians of Heilongjiang branch of China Southern Airlines are responsible for checking and maintaining airplanes to better cope with the upcoming Spring Festival travel rush. (Xinhua/Wang Kai)

A technician examines the appearance of an airplane in Harbin, northeast China's Heilongjiang Province, Feb. 10, 2018. About 50 technicians of Heilongjiang branch of China Southern Airlines are responsible for checking and maintaining airplanes to better cope with the upcoming Spring Festival travel rush. (Xinhua/Wang Kai)

Technicians examine and maintain the engine of an airplane in Harbin, northeast China's Heilongjiang Province, Feb. 10, 2018. About 50 technicians of Heilongjiang branch of China Southern Airlines are responsible for checking and maintaining airplanes to better cope with the upcoming Spring Festival travel rush. (Xinhua/Wang Kai)