DALLAS — More flights are arriving on time and airlines are losing fewer bags, yet more consumers are complaining about air travel.

Traveler complaints jumped 34 percent last year, to the highest level since 2000. The top frustration is problem flights including cancelations and delays, which is unchanged in 16 years.

“Everything is getting better, but they are still unhappy about the same things,” says Dean Headley, a marketing professor at Wichita State and co-author of an annual report on airline quality. He thinks passengers resent the growth in extra fees for things like checked baggage and changing or canceling a reservation, and that makes them quicker to complain when something goes wrong with their trip.

The report by Headley and Brent Bowen, dean of the aviation school at Embry-Riddle Aeronautical University, is being released Monday. The researchers use publicly available information from the U.S. Department of Transportation to rate the airlines for on-time performance, baggage handling, bumping passengers because of oversold flights, and complaints filed with the government.