The performance of the runway and corresponding facilities determines what level of aircraft can use this airport. Airports are classified according to this ability, which is called flight zone level. The flight zone level is represented by a two-part code. The first part is a number, which indicates the runway performance and obstacle limit corresponding to the aircraft performance. The second part is letters, indicating the width of runway and taxiway required by the size of the aircraft. Therefore, for the runway, the first number of the height layer of the flight area indicates the required flight field length, and the second letter indicates the maximum span and the maximum track width of the corresponding aircraft. Their corresponding data are as follows:

The first number

Digital flight field length

1- less than 800 meters

2-800m to1200m

3-1200m to1800m

4- 1800 meters above

The second letter

Letter span wheel spacing

Less than 5 meters and less than 4.5 meters

B-5m to 24m-4.5m to 6m

C-24m to 36m-6m to 9m

D-36 to 52m-9m to 14m

East -52m to 60m-9m to 14m.

At present, the flight zones of most open airports in China are above 4D, and the flight zones of Gao Qi in Xiamen, Changle in Fuzhou, Beijing Capital, Taoxian in Shenyang, Zhoushuizi in Dalian, Hongqiao in Shanghai, Pudong in Shanghai, Lukou in Nanjing, Xiaoshan in Hangzhou, Baiyun in Guangzhou, Baoan in Shenzhen, Tianhe in Wuhan, Phoenix in Sanya, Jiangbei in Chongqing, Shuangliu in Chengdu, Wujiaba in Kunming, Gongga in Lhasa, Xianyang in Xi 'an and Diwobao in Urumqi are currently graded.