Complaints Soar, But Airlines' Quality Rating Stays High : The Two-Way Customers are more unhappy, but the carriers continue to improve their on-time performances and they're losing fewer bags. Those are among the reasons the quality of the airlines' work remains high, according to a respected study. Virgin Atlantic gets the best score. United gets the lowest.

Complaints Soar, But Airlines' Quality Rating Stays High

In what would seem to be a contradiction, a respected study says that the quality of service provided by U.S. airlines remained near an all-time high last year even as passengers' complaints soared 22 percent.

The 2013 Airline Quality Rating Report from researchers at Purdue University and Wichita State University shows almost no change from 2011, which according to the schools' formula was the best year U.S. airlines have had, in terms of quality. This is the 23rd year the report has been compiled.

The researchers look at not just customer complaints, but also on-time performance, "denied boardings" and baggage problems. Complaints are up, Wichita State business professor Dean Headley tells The Associated Press, because airlines continue to pack planes, shrink seats, add charges and take other steps to boost revenue.

But on-time performance improved. An estimated 81.8 percent of flights were on time in 2012 versus 80 percent the year before.

Also on the plus side, there were fewer mishandled bags in 2012: 3.07 per 1,000 passengers versus 3.35 in 2011.

Still, along with the number of complaints, the other bad news was that the number of "involuntary denied boardings" went up — to 0.97 per 10,000 passengers last year from 0.78 in 2011.

As for the airlines and where they rank in terms of quality, here's the latest list:

1. Virgin America

2. JetBlue

3. Air Tran

4. Delta

5. Hawaiian

6. Alaska

7. Frontier

8. Southwest

9. US Airways

10. American

11. American Eagle

12. SkyWest

13. ExpressJet

14. United