Southwest Airlines Co., the third-busiest carrier at Denver International Airport, keeps losing money. For a second consecutive quarter, the Dallas-based airline posted losses--this time $56 million, or 8 cents per share--according to the Denver Business Journal, which notes that the airline saw $111 million in gains just one year ago. The reason for the struggle is the airline's bad betting on fuel prices, a problem that has also struck DIA's largest carrier, United Airlines. Earlier this week, United announced a $1.3 billion loss for the fourth quarter, adding 1,000 workers to its rising number of layoffs, according to The Associated Press. It is unclear how the layoffs will play out in Denver. While United expects reduced demand, officials for AeroMexico are hopeful a new flight between Denver and Mexico City, which starts February 1, will draw customers, according to The Denver Post.