The U.S. Department of Transportation says Dallas-based Southwest Airlines sat at the bottom of December on-time rankings.
Southwest only had 57.7 percent of their flights arrive on time, according to the federal rankings.
Fort Worth-based American Airlines did better, with 70.5 percent flights arriving on time, but both Southwest and American were in the bottom half of the rankings.
Hawaiian Airlines stayed on top of the list with 92.4 percent of their flights arriving on time.
Here are the federal government's ranking of U.S. airlines, by what percentage of their flights arrived on time during December: