Southwest Airline Co. (NYSE:LUV) turned lower in premarket action on Thursday as investors digested the lawsuit filed by the Department of Transportation over violating rules establishing realistic flight schedules and disrupting the travel plans of passengers.

The Department of Transportation is suing Southwest Airlines, accusing it of operating two “chronically delayed flights” in 2022 that resulted in 180 flight disruptions.

The Transportation Department said in a lawsuit that two of the airline’s routes were consistently delayed in violation of federal rules.

The Department of Transportation on Wednesday sued Southwest Airlines, alleging the carrier operated chronically delayed flights, and fined Frontier Airlines for late-arriving flights.

This "sends a message to all airlines" that DOT will go to court in order "to enforce passenger protections," Pete Buttigieg said.

A lawsuit filed against Southwest alleges the airline operated multiple “chronically delayed” flights affecting thousands of passengers.

A Southwest Airlines pilot has been arrested by airport police, accused of driving under the influence before a scheduled flight. The airline confirmed the pilot has been removed from duty. This incident comes as the Department of Transportation sues Southwest over persistent flight delays.

The Transportation Department is stepping up enforcement of persistent flight delays with a lawsuit against Southwest Airlines and a fine against Frontier Airlines.