Karishma Vanjani

Southwest Airlines stock tumbled early Thursday morning after the Department of Transportation sued the Texas carrier "for illegally operating multiple chronically delayed flights and disrupting passengers' travel," the latest sign of heavier enforcement by the government.

An investigation by the DOT found that Southwest flights operating on two routes -- Chicago and Oakland, Calif., and between Baltimore and Cleveland -- resulted in 180 flight disruptions between April and August 2022. Each flight was chronically delayed for five straight months.

A flight is chronically delayed if it is flown at least 10 times a month and arrives more than 30 minutes late more than half of the time, a lawsuit by the DOT published on Wednesday said.

The agency said it "seeks maximum civil penalties."

Southwest didn't immediately respond to a request for comment from Barron's. Southwest told The Wall Street Journal that it was disappointed by the suit and that the two flights didn't reflect its operation. "Any claim that these two flights represent an unrealistic schedule is simply not credible when compared with our performance over the past 15 years."

Southwest stock was down 3% to $31.81 in premarket trading on Thursday.

The agency also fined Frontier Group Holdings' Frontier Airlines unit $650,000 in civil penalties for operating multiple chronically delayed flights. Frontier didn't immediately respond to a request for comment.

Earlier this month, JetBlue Airways was fined $2 million for chronic flight delays and unrealistic scheduling.

Write to Karishma Vanjani at karishma.vanjani@dowjones.com

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January 16, 2025 08:37 ET (13:37 GMT)

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