Consumers might be complaining more, but airline quality made improvements.

The 2013 Airline Quality Rating report found consumer complaints climbed 22% last year, but quality remained mostly unchanged from 2011.

The report, compiled from researchers at Purdue University and Wichita State University, measures consumers’ gripes, time performance of airlines, “denied boardings” and baggage issues.

The overall industry quality rating score showed that the on-time arrival percentage was better at 81.8% in 2012 compared to 80.0% in 2011. Mishandled baggage rates also improved to 3.07% per 1,000 passengers in 2012 to 3.35% per 1,000 passengers in 2011.

Involuntary denied boardings climbed to 0.97% per 10,000 passengers in 2012 from 0.78% in 2011.

Complaints and quality are both up because of increased traffic, according to Roger Block, president of Travel Leaders Franchise Group. Many of the major airlines had either gone through mergers or bankruptcies, which has proven challenging.

“The United (NYSE: UAL) merger [with Continental Airlines] has created some challenges and upset loyal customers,” Block says. “They are working diligently to correct it, but it has skewed the number of complaints.”

Also, airlines are carrying at full capacity- meaning planes are more crowded and make the travel experience overall less pleasant.

“With more people in the aircraft, that means all middle seats are filled and the actual experience, depending on how full the plane is, creates an environment that will foster unhappiness,” Block says.

The on-time factor and lost baggage factors have both improved, meaning the fundamentals of good service have gotten better, he says. And, consumers speaking up is only helping the trend, he says.

Here are the top 10 airline rankings from this year’s survey:

1. Virgin America

2. JetBlue (NASDAQ: JBLU)

3. Air Tran

4. Delta (DAL)

5. Hawaiian (HA)

6. Alaska (ALK)

7. Frontier

8. Southwest (LUV)

9. US Airways (LCC)

10. American (AMR)

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