Americans Complained About Airlines A Lot Less In 2013

Southwest AirlinesSouthwest Airlines registered the fewest passenger complaints in 2013.

The U.S. Department of Transportation received 13,168 complaints about airline service in 2013, a 14.1% drop compared to the 15,338 it fielded in 2012.

But while the year was good overall, things weren't so nice once winter set in.

According to new numbers from the DOT, December complaints jumped 23.5% over December 2012, and 47.5% over November 2013.

That's not surprising, considering that, according to FlightStats, only 71.78% of North American flights were on-time in December 2013, compared to 84.16% in November 2013.

Complaints sent to the DOT cover flight delays and cancellations, mishandled baggage, oversales, fare increases, misleading advertising, poor treatment of animals, and discrimination.

Among U.S. airlines, Frontier was the subject of the highest rate of complaints - 3.09 per 100,000 passengers. Southwest came out on top, with just .34 complaints per 100,000 passengers.