Hainan Airlines saw operating profit decline 36% to CNY150 million ($21.3 million) in the third quarter.
The Chinese carrier boosted revenue 11% to CNY21.4 billion, but total costs rose by a similar margin, reaching CNY21.8 billion.
Net profit fell 40% to CNY108 million.
Across the first nine months of the year, operating profit was down 7.2% at CNY850 million. Total revenue climbed 7.9% to CNY56.5 billion, while total costs were 8.4% up at CNY58 billion.
Nine-month net profit came in at CNY850 million, a decline of 7.2% from the previous year's equivalent figure.
Like other listed Chinese carriers, Hainan Airlines does not provide commentary on its financial results.