China's independently-developed ARJ21 regional jetliner has been verified capable of operating in all high-plateau airports, its developer announced Thursday after due testings.

An ARJ21 airplane returned to Shanghai on Thursday after completing a half-month flight test, which thoroughly examined the aircraft's operation capacity in a high-plateau airport environment, said the Shanghai-based Commercial Aircraft Corporation of China (COMAC).

The ARJ21 aircraft completed the expanded tests on its performance on the maximum take-off and landing altitude at Daocheng Yading Airport located in Ganzi Tibetan Autonomous Prefecture in southwest China's Sichuan Province.

Located 4,411 meters above sea level, it is the world's highest-altitude civilian airport.

The tests verified that ARJ21 is capable of operating in all high-plateau airports, and paved the way for airlines to use the aircraft to open more high-altitude routes, said the COMAC.

The ARJ21 is China's first turbo-fan regional passenger jetliner model and is designed with 78 to 90 seats and a range of 3,700 km. It can fly in alpine and plateau regions and is adaptive to various airport conditions.

Plateau airports refer to those airports with an altitude of more than 1,500 meters above sea level. They include high plateau airports that are more than 2,438 meters above sea level.

China has the world's largest number of plateau airports, of which 19 are high plateau airports. Most of these airports are located in the western regions.

According to the Chinese commercial aircraft maker, the COMAC values high demands from the Chinese civil aviation market, especially those in the western regions.

The plateau operation attaches high requirements on the aircraft to maintain safety in high-altitude environment with thin air, complex terrains and changeable weather.

The ARJ21 development team took the high-altitude performance and operation capacity as key design targets of the regional jetliner model, said the COMAC.

In 2013 and 2017, the ARJ21 aircraft carried out flight tests at two Chinese airports, respectively, at altitudes of 2,842 meters and 2,905 meters.

The latest test flights in Daocheng expanded the aircraft's maximum take-off and landing altitude, and further verified its reliability and plateau performance, the COMAC added.

As a pioneer of Chinese commercial airplanes, the ARJ21 aircraft was put into commercial service in June 2016 by Chengdu Airlines.

As of July 22, the COMAC delivered a total of 33 ARJ21 airplanes to its customers. They are serving on air routes linking 56 cities, according to the COMAC.