The on-time performance of Southwest Airlines, the nation's largest domestic carrier, improved slightly in August but continues to lag behind nearly every other major carrier, according to data released Thursday.
The Dallas-based carrier acknowledged in July that its on-time performance had dropped in the last year because the airline scheduled too many flights during the most popular takeoff times.
Southwest executives said they began adding more "cushion" time between flights several months ago to address mechanical glitches or other problems that could trigger takeoff delays.
Still, airline data for August show that Southwest flights arrived on time 75.8% of the time, below the 77.7% average for all major airlines in the U.S., according to the Department of Transportation.
Southwest's on-time performance was 70% in June.
Hawaiian Airlines ranked at the top, with an on-time performance of 94%, according to the federal report.
Southwest Airlines ranked at the top in another ignoble category: The most chronically late flights.
In August, 2.9% of all of Southwest Airline's regularly scheduled flights for the month were late 70% of the time, while the industry average was less than 1%, according to the Department of Transportation.
Southwest said it expects its performance to improve throughout the year.
"We will continue monitoring our performance metrics closely so that we can make any additional investments necessary to meet customers' expectations for our legendary Southwest hospitality," the airline said in a statement.