Virgin America, JetBlue and Hawaiian Airlines emerged Monday as the best-performing US air carriers in 2013, a year that generally saw improvements in air travel. Overall, airline performance "was the highest since 1991," according to the 24th annual Airline Quality Rating, compiled by Embry-Riddle Aeronautical University and Wichita State University. There were fewer involuntary denied boardings and customer complaints compared to 2012, although performance dipped somewhat in terms of on-time arrivals and baggage handling, the study suggested. "When you look at the past 14 years, you find that the airline industry performs most efficiently when the system isn't stressed by high passenger volume and the number of airplanes in the air," said study co-author Dean Headley, an associate professor of marketing at Wichita State. "The challenge is whether airline performance quality improvements at this level can be maintained as more people choose to fly. Or does the infrastructure and air traffic control technology limit what the airlines can actually do?" Virgin America and JetBlue took first and second place, as they did in the 2012 ranking, while Hawaiian moved up two places to number three, followed by Delta and Alaska. Newcomer Endeavor, formerly Pinnacle, came sixth, followed by US Airways, Southwest, American, AirTran, Frontier, United, ExpressJet, SkyWest and American Eagle, respectively. Hawaiian clocked the best on-time performance at 93.3 percent, and American Eagle, a commuter carrier, the worst at 72.1 percent. Southwest drew the fewest customer complaints, and Frontier the most. Using data from the Department of Transportation, the Airline Quality Rating employs weighted averages to take stock of airline performance -- a method deemed more objective than infrequent and subjective passenger surveys. The latest edition, released in Washington, is posted at airlinequalityrating.com.