The DOT filed a lawsuit against Southwest Airlines, citing a pattern of chronic delays, as the government pushes for stricter accountability.

The DOT's moves come weeks after issuing a multi-million dollar fine against JetBlue.

Southwest Airlines is being sued and Frontier Airlines fined over chronic flight delays by the Department of Transportation, the DOT announced Wednesday. Why it matters: Wednesday's announcement by the outgoing Biden administration's Transportation Secretary,

The lawsuit alleges Southwest illegally operated chronically delayed flights and disrupted passengers' travel plans.

Southwest Airlines was sued in federal court by the Department of Transportation, while Frontier was hit with a $650,000 fine.

While the initial fine was $325,000, the DOT warned that if Frontier Airlines continues to chronically delay flights, the penalty will double.

Frontier Airlines recently announced new benefits for members of its loyalty program, including a fast-track offer that helps travelers achieve Elite Platinum status with as little as 20,000 points.

(ABC 6 News) — The U.S. Department of Transportation says it is prepared to take airlines to court over flight delays. The agency has filed a lawsuit against Southwest, accusing the airline of illegally operating chronically delayed flights and disrupting passengers’ travel plans.

According to Sharon Petersen, the CEO of AirlineRatings.com, while Air New Zealand came in first place for the world’s safest full-service airline, it was a pretty close race. There was only a 1.5-point difference between that airline and Qantas, which both “uphold the highest safety standards and pilot training,” as noted by Petersen.

Southwest Airlines stock fell Thursday after the Department of Transportation sued the airline over a pair of "chronically delayed flights."

The lawsuit filed in California alleges that Southwest illegally operated chronically delayed flights and disrupted passengers’ travel plans.

The U.S. Transportation Department is suing Southwest Airlines and has fined Frontier Airlines over "chronically" delayed flights, disrupting passengers' travel and plans.