Air China Ltd. and China Eastern Airlines Corp., China's biggest and third-largest carriers by market value, both reported record quarterly profit growth on the back of robust growth in domestic air travel and a strong yuan.

Air China said late Thursday its third quarter net profit rose more than fourfold to 5.17 billion yuan (749 million U.S. dollars). China Eastern, boosted by the Shanghai Expo, said profit jumped more than 130-fold to 3.16 billion yuan in the third quarter.

China Southern Airlines Company Limited, the nation's largest carrier by transport capacity, said early Thursday its third quarter net profit grew 970.77 percent to 3.04 billion yuan.

Domestic air traffic demand surged with the average percentage of seats used surpassing 80 percent in the third quarter. During the week-long National Day holiday, passenger numbers rose 24 percent year on year to 5.75 million while the number of flights increased by merely 5.3 percent.

Domestic air carriers are buying new planes to cope with the increasing demand. Air China has ordered four Boeing 777-300ER aircraft and its affiliated Shenzhen Airlines has purchased 10 Airbus A320. Xiamen Airlines, 60-percent-owned by China Southern, also ordered 10 Boeing aircraft.

The airlines also have benefited from the yuan's appreciation.

Huang Jinxiang, an analyst at Sinolink Securities, said air traffic demand would drop in the fourth quarter but the performance of the carriers would be significantly better than the same period of last year.