Air corridor, it is passageway of the flight in the air that there is 4-5 kilometer breadth each in the two side that connected a line at 2 o'clock, the flight between dot and dot is carried out inside corridor for aerostat. Set the goal of air corridor, it is to make aerostat undertakes strictly flying according to corridor, avoid aerostat to enter the limitative area besides corridor. The big city such as Beijing, Shanghai, Guangzhou, Chengdu, Xi'an, Shenyang sets air corridor. The plane goes to the airport of these big cities, in the sky cannot fly across a city to go to the airport directly at will, must fly to designation place first (namely corridor mouth) , next along air corridor, fly to the airport to descend again.