A stewardess guides a returning worker to board a chartered airplane of Shenzhen Airlines at Xi'an Xianyang International Airport in Xianyang, northwest China's Shaanxi Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Shao Rui)

Returning workers board a chartered airplane of Shenzhen Airlines at Xi'an Xianyang International Airport in Xianyang, northwest China's Shaanxi Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Shao Rui)

Stewardesses hold posters to welcome returning workers in a chartered airplane of Shenzhen Airlines at Xi'an Xianyang International Airport in Xianyang, northwest China's Shaanxi Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Shao Rui)

A stewardess pastes a poster to welcome returning workers in a chartered airplane of Shenzhen Airlines at Xi'an Xianyang International Airport in Xianyang, northwest China's Shaanxi Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Shao Rui)

Returning workers take a chartered airplane of Shenzhen Airlines heading for Zhejiang Province at Xi'an Xianyang International Airport in Xianyang, northwest China's Shaanxi Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Shao Rui)

A staff member conducts a chartered airplane of Shenzhen Airlines from Sichuan Province at Shenzhen Airport in Shenzhen, south China's Guangdong Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Mao Siqian)

Returning workers get off a chartered airplane of Shenzhen Airlines from Sichuan Province at Shenzhen Airport in Shenzhen, south China's Guangdong Province, Feb. 27, 2020, Five chartered airplanes of Shenzhen Airlines carried returning workers back to work Thursday. (Xinhua/Mao Siqian)