Juneyao Airlines' (SHA:603885) available seat kilometers, which measure passenger capacity, slipped 0.3% year on year to 4.74 billion in May, according to a Shanghai bourse filing on Tuesday.
Passenger traffic, measured as revenue passenger kilometers, rose 1.2% year on year to 4.14 billion.
Cargo and mail volume jumped 11% to 15,310.54 tons from a year earlier.
The Chinese airline company's shares fell 2% during the afternoon trade.