Hawaiian Airlines ranked fifth in an annual quality survey of the nation’s nine largest airlines.

Academics at Wichita State University and Embry-Riddle Aeronautical University released their 29th annual study Monday. They used last year’s data from the U.S. Department of Transportation for the categories of on-time arrivals, mishandled baggage, bumping passengers and consumer complaints.

Delta Air Lines, JetBlue Airways, Southwest Airlines and Alaska Airlines finished ahead of Hawaiian, which dropped a notch after being ranked fourth last year. Behind Hawaiian in this latest survey were United Airlines, Spirit Airlines, American Airlines and Frontier Airlines. Alaska’s results include the performance of Virgin America, which Alaska completed its purchase of in April 2018.

Overall, the industry improved in three of the four categories in the study, including fewer passengers being involuntarily bumped from a flight. Airlines have been cutting that rate for several years by enticing more customers to take vouchers or other compensation in exchange for volunteering to get off oversold flights.

Separately, Hawaiian reported Monday that its passenger traffic slipped 2.5% in March to 993,548 from 1,018,741 in the year-earlier period. Its load factor, or the percentage of seats filled, dipped to 86.4% from 86.5%. Revenue passenger miles, or one paying passenger transported one mile, remained virtually flat at 1.44 billion while available seat miles, or one seat transported one mile, also held steady at 1.67 billion.

The state’s largest carrier also narrowed its first-quarter estimates for operating revenue per available seat mile to down 3% to down 5%, a slight improvement from its earlier estimate of down 3% to down 6%. Hawaiian also lowered its estimates for operating costs per available seat mile, excluding fuel, primarily due to lower-than- expected expenses related to its neighbor island freighter operations. Hawaiian projected its cost per available seat mile for the first quarter to be up 0.5% to up 2.5%. That is lower than its previous estimate of up 1% to up 4%.