The scheduled flight was carrying 124 customers and a crew of five from Chicago Midway to Branson, Southwest said. Instead it landed at the Taney County airport, also in Branson.
The runway at Taney County is only about half the length of the one at the intended airport -- 1,139 meters compared 7,140 -- which could have posed a problem for the Boeing 737.
But with immediate, heavy breaking, the pilot was able to stop the plane about 500 feet before the end of the runway with no injuries, emergency and airport officials told CNN.
And a day later, officials were still scratching their heads.
More From This Section
"We continue to look into the circumstances which led the pilot in command of flight 4013 from Chicago Midway to land ... Several miles from the Branson Airport we serve," the airline said.
"We are cooperating with authorities in this investigation."
"We have since reached out to each customer directly to apologize, refund their tickets, and provide future travel credit as a gesture of goodwill for the inconvenience," it pledged.
A different plane had been brought to the Branson airport to pick up the passengers continuing to the flight's final destination in Dallas last day.