Travel buyers take note: the average service performance of the 16 U.S. airlines hit a new low in 2007 according to a recent study and the outlook is for more stormy skies.

According to the 18th annual national Airline Quality Ratings (AQR) study conducted by researchers at the University of Nebraska-Omaha and Wichita State University, only four of the airlines tracked improved their rating this year, which is based on several different metrics including on-time performance, denied boardings, mishandled baggage and host of customer complaints.

Overall, on-time performance for the 16 airlines tracked in 2007 was 73%, down from 75% in 2006 and the fifth straight year of decline. More than one-quarter of all flights were late, according to the survey. The rates of bags lost, stolen or damaged also jumped in 2007. AirTran had the best baggage handling rate, at 4.06 mishandled bags per 1,000 passengers while American Eagle ranked last in baggage handling with 13.55 mishandled bags per 1,000 passengers.

Researchers said as higher fuel prices force airlines to cut corners in other areas, their service levels have plummeted. Airlines declined in all areas of performance, and researcher Dean Headley, associate professor and chair of marketing at Wichita State University said “I don't expect to see better airline performance in the near future. There's no incentive,” Headley said. “The airlines are losing money. Fuel prices are high. They're cutting back on services. They're cutting back on people. Everything it takes to run an airline is more expensive, and the airlines want less of that expense.”