Southwest Airlines' load factor increased by 0.6 percentage point to 75.8% in February compared with a year earlier.
The carrier reports an about 2% increase in passenger revenue per available seat mile (PRASM) during the month.
Passenger traffic declined 2.3% during the month while capacity fell 3.1%. Southwest's revenue passenger numbers fell 4.4% to 7.63 million passengers.
There was one less day in February compared to 2012 due to leap year.