NGARI/CHENGDU, May 28 (Xinhua) -- An Airbus A319 passenger plane completed a test flight Friday by landing at Gunsa Airport in southwest China's Tibet Autonomous Region, a month before the airport, the fourth civilian-use airport on the "Roof of the World," begins operations.

The Air China plane took off from Shuangliu Airport in Chengdu, capital of neighboring Sichuan Province, at 5:30 a.m. and landed at Gunsa Airport less than four hours later, Air China's Southwest Branch said in a press release.

The pilot used the advanced Required Navigation Performance (RNP) precision-approach technology to land the aircraft, the first such attempt at a plateau airport, the release said.

RNP allows an aircraft to fly a designated path between two 3-dimensionally defined points in space.

After the test flight, the crew invited a group of Tibetan farmers and herdsman aboard the plane for a brief flight over their hometown.

Air China's Southwest Branch mainly operates routes to southwestern China's Sichuan, Yunnan and Guizhou provinces, Tibet, and Chongqing Municipality.

Once the new airport becomes operational, the company will launch a new air route from Chengdu to Ngari via Lhasa on June 28, vice general manager Li Yunchuan said.

Gunsa Airport in Ngari sits more than 4,200 meters above sea level and has a 4,500-meter-long runway. Its annual throughput capacity is expected to reach 120,000 passengers by 2020.

Construction of the airport began in May 2007 and it cost an estimated 1.647 billion yuan (241.22 million U.S. dollars).

It will be the fourth operational civilian-use airport in Tibet after Gonggar Airport in Lhasa, Bamda Airport in Qamdo Prefecture and Nyingchi Airport.

A fifth airport, Peace Airport in Xigaze, is expected to begin operations in October.