The course that the airlines flies calls line of the traffic in sky, abbreviation course. The course of the plane decided the airlines flies to particular way, the beginning and the end is nodded and be nodded via stopping not only, and return the need according to air traffic control, set the width of course and flight height, in order to uphold order of the traffic in sky, make sure the flight is safe. Aircraft line is decided really besides safe element, depend on the size of economic benefits and social benefit. Usually, course arrangement is a center with big city, main line is built between big city, at the same time complementary with feeder line, come by big city radiate all round small town. The attributive and different cent that course nods by the beginning and the end is international course and domestic line. The course inside its China can be divided again for main line and feeder line. Main line is to show join Beijing and each provincial capital, municipality directly under the Central Government or municipal metropolis or each province, municipality place belongs to the course between the city, be like Beijing, Shanghai course, Shanghai, Nanjing course, Qingdao, Shenzhen course. Feeder line is to point to the course between each city in a province or municipality.
