Southwest Airlines is once again feeling the ire of federal regulators, as the Department of Transportation on Thursday imposed a $1.6 million fine against the airline for forcing passengers to stay on planes for hours at Chicago’s Midway airport in January 2014.

The Chicago Tribune reports that the $1.6 million fine is the largest ever civil penalty levied by the DOT under a 2009 rule that prohibits tarmac delays of more than three hours without allowing passengers to get off the aircraft.

DOT officials say that on January 2 and January 3 of last year, 16 Southwest flights experienced lengthy tarmac delays exceeding three hours at Midway.

The holdups occurred when severe weather and a malfunction of Southwest’s crew scheduling systems created a shortage of staff. The shortage particularly affected the carrier’s ramp-crew, which prevented Southwest from being able to clear aircraft from the gates in a timely manner.

“Airline passengers have rights, and the Department’s tarmac delay rules are meant to prevent passengers from being stuck on an aircraft on the ground for hours on end,” Anthony Foxx, U.S. Transportation Secretary, says in a statement. “We have aggressively enforced, and will continue to aggressively enforce, our tarmac delay rule to ensure carriers have adequate resources to minimize passengers’ exposure to lengthy tarmac delays.”

The DOT said it assessed a larger penalty against Southwest because the tarmac delays involved more flights and impacted more passengers than previous cases.

Since the rule took effect, the DOT has issued 17 orders assessing a total of $5.24 million in civil penalties.

The largest previous fine of $1.1 million was handed down to United Airlines for the 2012 delays experienced at Chicago’s other airport, O’Hare.

Thursday’s fine represents the second multimillion penalty Southwest has received from federal regulators in the last six months. Back in July, the Federal Aviation Administration imposed a $12.6 million fine against the airline for alleged improper plane repairs. The FAA filed a lawsuit against the carrier in November for nonpayment of that fine.

Consumerist readers recently selected Southwest as the most likely company to have a turnaround year after a not-so-great 2014. Since this fine involves incidents from last year, we won’t hold it against the airline for 2015.

Southwest hit with record fine for delays [The Chicago Tribune]

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