(CNN) -- Discount airline AirTran Airways ranked first overall among 16 large U.S. carriers in 2010, according to an airline quality report released Monday.
AirTran improved in three of the four categories used to determine rankings in the Airline Quality Rating, an annual study based on analysis of Department of Transportation figures.
The airline improved in on-time performance, rate of consumer complaints and mishandled bags. AirTran's denied boarding performance was the only area where performance in 2010 was worse than 2009 (0.24 per 10,000 passengers in 2009 compared to 0.39 in 2010).
The report, co-authored by Brent Bowen of Purdue University and Wichita State's Dean Headley, shows overall airline improvement in 2010 over 2009. On-time arrival, the rate of mishandled baggage and involuntary denied boardings improved.
Despite indications of improvement overall, the rate of consumer complaints rose from .97 per 100,000 passengers in 2009 to 1.22 complaints per 100,000 passengers in 2010. The number of complaints rose from 7,120 in 2009 to 9,119 in 2010. Southwest Airlines maintained its standing as the airline with the lowest complaint rate with 0.27 per 100,000 passengers in 2010.
"With a mixed bag of gains and losses across the 16 carriers rated, the slight gain in AQR score for the industry is a positive sign. The improvement trend in AQR scores since 2007 speaks well of the industry efforts in difficult times," the report said.
The top scorer, AirTran, bumped 2009's No. 1 ranked Hawaiian out of the top spot. Hawaiian ranks second in 2010, followed by JetBlue, Alaska and Southwest.
Regional airline American Eagle ranked last among the 16 airlines. Also in the bottom five were Atlantic Southeast (ranked 15th), Comair (14th), Mesa (13th) and United (12th).