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

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

Yesterday, the United States and U.S. Department of Transportation (DOT) disclosed a lawsuit against Southwest Airlines, accusing the airline of chronically delayed flights and interrupting passengers’ travels.

Southwest is disappointed that DOT chose to file a lawsuit over two flights that occurred more than two years ago," a spokesperson for the airline said.

The Denver-based low-cost carrier said its combination with the Dania Beach, Florida-based Spirit would create a stronger low-cost carrier and benefit “from the very significant synergies Frontier expects to achieve by combining the airlines’ operations.”

Despite pressure to cut costs and an activist investor campaign, Southwest reported a healthy profit for the fourth quarter.

New flights have been added for Kansas City and Philly fans, with one airline adding flights on a route it doesn't normally serve.

American Airlines, Frontier Airlines, Southwest Airlines, United Airlines and Delta Air Lines have added a combined 31 new nonstop flights between Philadelphia International Airport (PHL ...

The Transportation Department is taking legal action against Southwest, alleging the airline illegally operated persistently delayed flights and disrupted passengers' travel plans.

Frontier said in a release that it has met with Spirit’s board and executives since it made its proposal this month.

Frontier Airlines is again pursuing a merger with Spirit Airlines, with Spirit mired in chapter 11 bankruptcy proceedings.