Complaints about airline service to the Department of Transportation rose 28 percent last year, according to an annual study of airline quality. How the 16 largest U.S. airlines stacked up, based on the number of complaints per 100,000 passengers:

_Delta Airlines, 2

_United, 1.64

_US Airways, 1.53

_Continental, 1.48

_American, 1.44

_Frontier, 1.23

_Comair, 1.25

_JetBlue, 1.25

_Hawaiian, 1.16

_American Eagle, 1.03

_AirTran, 0.90

_Skywest, 0.61

_Atlantic Southeast, 0.54

_Mesa, 0.53

_Alaska, 0.44

_Southwest, 0.27