Airline passengers filed 11,445 complaints with the Transportation Department last year, an increase of more than one-fifth from 2011.
The rate of complaints per 100,000 passengers also rose, from 1.19 in 2011 to 1.43 last year.
A breakdown of that rate for the 14 largest U.S. carriers from a report being released Monday on airline quality by researchers at Purdue University and Wichita State University. The first rate is for 2012; the second for 2011.
,Air Tran: 0.91; 0.72