Internal memo: Southwest flew 56 flights with no passengers earlier this week

Even though Dallas-based Southwest Airlines continues to slash capacity, the carrier is struggling to fill planes.

Southwest Airlines Co. (NYSE: LUV), the second-busiest carrier in Houston, operated 56 flights with zero passengers on board March 30, according to an internal memo sent to some employees and viewed by the Dallas Business Journal. A Southwest spokesperson said the company does not confirm information that may have been shared internally.

The situation in the memo underscores the new…