Call it a three-peat. Virgin America, which has evolved from a niche West Coast player into a carrier making its mark nationwide, was named the top airline in the annual Airline Quality Rating for the third-straight year. Tweet this It was followed by Hawaiian Airlines in second, and then Delta, which was named the most improved airline in this year's AQR report. "Delta is an excellent example of a merger that declined in performance and systematically has clawed its way back to a new high level of quality performance," said Brent Bowen, dean of the College of Aviation at Embry-Riddle Aeronautical University in Prescott, Arizona. Read MoreOfficial airline of the PGA loses golfer's clubs

On the flip side the Envoy/American Eagle, a regional airline, finished last, just behind ExpressJet and SkyWest.

Embry-Riddle Aeronautical University and Wichita State University have been measuring airlines' performance in the AQR for 25 years.

Oktay Ortakcioglu | Vetta | Getty Images

In what seems like a broken record, the quality of airline service deteriorated last year as carriers continued to squeeze passengers in numerous ways.

"As a group they generally did worse," said Dean Headley of Wichita State University. "We track four elements that we think are consumer relevant, on-time, baggage handling, complaints and things like that, and literally all four of those got worse for the industry this year." This latest study found airline service suffered as they packed more people onto planes and landed fewer flights on time. Read More

Perhaps the most telling indication of how frustrated passengers have become is the number of complaints about airlines filed last year with the Department of Transportation.

"They (complaints) are up 20 to 25 percent this year over last year and they were up before that so they (customers) are complaining more about a system that just is not working," said Headley. Overall, the quality of service has dropped to its lowest level since 2008. In addition to a spike in complaints about airline service, the AQR also found: On-time arrivals dropped 2 percent;

A slight increase in the percentage of passengers bumped from flights;

Mishandled baggage climbed 11 percent. The slumping performance of airlines confirms what many critics feared would happen when major carriers started merging six years ago. Since 2008, there have been four mergers among the eight largest U.S. airlines.

The best US airline is... Ranking Airline Last year's ranking 1 Virgin America 1 2 Hawaiian 3 3 Delta 4 4 JetBlue 2 5 Alaska 5 6 Southwest (includes AirTran) 8 7 American (includes US Airways) 9 8 Frontier 11 9 United (includes Continental) 12 10 SkyWest 14 11 ExpressJet 13 12 Envoy/American Eagle 15