Daocheng Yading Airport in Daocheng County, Ganzi Tibetan Autonomous Prefecture, Sichuan Province is on a plateau with an altitude of 4,411 meters and a temperature of 10°C only.

　　"The helicopter is in good condition. Can it take off?" At 9 o'clock on September 27, the high-altitude scientific flight test of AVIC Helicopter Design and Research Institute was formally started at Daocheng Yading Airport. Zeng Guogui, chief designer of AR-500C, issued a takeoff instruction. Then, the unmanned helicopter took off from the ground and hovered steadily at 10 meters above the ground. It successively completed the tests of hovering rotation and flight in every direction.

　　Flight of a helicopter relies on the reverse thrust from the air below the rotor, and the lifting force produced by the rotor in a plateau area is greatly reduced. At an altitude of 4000 meters, the air density is about 60 to 70% of that at the sea level, and the power of a helicopter drops by about 40%.

　　At the same time, the engine also needs air for combustion, and lower density of air means the need for higher air intake. Therefore, the speed of both the air intake fan and the rotor needs to be increased, or more blades need to be installed.

　　After the unmanned helicopter AR-500C flew for 15 minutes, it landed steadily. The data showed that the unmanned helicopter was in good condition, indicating a good plateau flight performance. AVIC Helicopter Design and Research Institute has set a new record of take-off and landing altitude of home made unmanned helicopters.