Three years into the new decade, America’s most successful airline of all time was no longer—by its own lofty standards, anyway—so successful. In 2012, for the second straight year, Southwest had underperformed the U.S. industry average with mid-single-digit operating margins, conjuring uncomfortable worries that its future might never be as bright as its past. Then things started to improve, and by 2015, Southwest was producing profits that even its old self would have envied.
