Last year was one of the worst for U.S. airline service in the past five years, according to FlightStats Inc., which tracked more than eight million trips.

Overall, airline reliability ranked second worst of the past five years when considering on-time flights (2011 was the worst), and last year was the worst when considering delays over 45 minutes.

Airlines canceled and delayed more flights in 2013 than in 2012, even though airports were less crowded as carriers offered fewer flights. About 78 percent of flights arrived on time last year, compared to 80 percent in 2012. Flights delayed by 45 minutes or longer jumped 13 percent in 2013 from 2012, and flight cancellations jumped 15 percent, the Wall Street Journal reported on Wednesday.

On-time flights influence other key areas of service, including baggage handling. Not surprisingly then, more luggage was lost or delayed last year. Southwest Airlines (NYSE:LUV), the only carrier still offering two free checked bags to customers, is primarily to blame for the luggage woes. Southwest erred with more bags last year than United, which is operated by United Continental Holdings Inc: (NYSE:UAL), and Delta Air Lines, Inc. (NYSE: DAL) combined, according to the U.S. Transportation Department.

Some of the delays, such as at Southwest, arose because airlines wrote schedules based on better weather. In good weather, the flights arrived slightly earlier than scheduled, but in worse than expected weather, planes took longer to load and unload, creating more delays.

Southwest’s Chief Operating Officer Mike Van de Ven told the Wall Street Journal that the airline’s schedules are being rewritten and will take effect in the second half of this year. He also said Southwest’s baggage handling reflects the heavy volume from not charging baggage fees and accepting bags late. Southwest will upgrade baggage sorters and other equipment at major airports.

Delta boasts the lowest rate of canceled flights in the industry, at 0.34 percent of its schedule, FlightStats said. The industry’s average in 2013 was 1.65 percent.

United and American Airlines Group, Inc. (Nasdaq:AAL) have ranked at the bottom of that list the past three years. American ranked the worst last year, canceling nearly 2 percent of its flights.

A spokeswoman for American told the Wall Street Journal that the airline is focusing on its merger with US Airways and improving reliability next year.