WASHINGTON --- Airlines did a lot right last year.
They were better at arriving on time and not overbooking planes so people got bumped less often from flights. Their rate for losing or damaging bags was the lowest in 20 years.
But don't tell that to passengers, who made it clear that not all was friendly in the skies in 2010.
Complaints to the Department of Transportation about airline performance went up a whopping 28 percent from the year before, according to an annual study of airline quality being released today.
It's hard to nail down a precise reason for that spike in consumer disenchantment, but it's most likely because of changes in the way airlines are doing business, said Dean Headley, a co-author of the report that's based on department data.
The number of air travelers is increasing, but there are fewer flights and fewer seats available. So, flights are more crowded and it's tougher to rebook when a flight is canceled.
"They are trying to match supply and demand -- the number of seats available to the number of people demanding seats -- a lot closer so they don't fly empty seats, which is expensive for the airlines," said Headley, an associate professor of marketing at Wichita State University.
That increases chances that some passengers are going to be unhappy because mismatches between passengers and seats available usually are managed to the airline's advantage, he said.
"Even though airlines are vocal about saying they want to please the customer, when it comes right down to it, they're going to make money first," Headley said.
There were 1.22 complaints per 100,000 passengers last year, compared with less than one per 100,000 in 2009.
An overall ranking of the nation's 16 largest airlines based on their combined performance in four categories -- on-time arrivals, mishandled baggage, denied boardings, complaints -- comes out at 9:30 a.m. today.
Southwest Airlines maintained its ranking as the airline with the lowest consumer complaint rate, 0.27 per 100,000 passengers in 2010. Delta had the worst rate again, two per 100,000 passengers.
Four of every five domestic flights arrived on time last year, a slight increase from 2009. Over the past 20 years, on-time performance has ranged from a high of 82.5 percent in 1991 to a low of 72.6 percent in 2000.
Eight airlines had an on-time arrival percentage over 80 percent. Hawaiian Airlines was the best, at 92 percent. Comair, a regional airline, was last at 73 percent.
AirTran had the best baggage handling rate, 1.6 mishandled bags per 1,000 passengers; American Eagle had the worst, 7.15.
American Eagle had the best rate of involuntary denied boardings, at four per 10,000 passengers. JetBlue, which has a policy against overbooking, had the lowest, 0.01.