The Transportation Department on Friday announced a $2 million penalty against JetBlue Airways for operating several East Coast flights that arrived chronically late in 2022 and 2023. Half of the money collected goes to the affected passengers.

The penalty marks the first time the DOT has fined an airline for chronic delays. The federal agency defines these as flights that are flown at least ten times a month and arrive more than half an hour late in more than 50 percent of cases.

“Illegal chronic flight delays make flying unreliable for travelers. “Today’s action puts the entire aviation industry on notice that we expect their flight schedules to reflect reality,” Transportation Secretary Pete Buttigieg said in a statement.

The DOT said it warned JetBlue of ongoing delays on its flights between Kennedy International Airport and Raleigh-Durham International Airport in North Carolina. It added that airlines had a “legal responsibility to avoid chronic delays” and that these months-long flights were unfair and misleading.

The four routes examined flew between JFK and Raleigh-Durham Airport; JFK and Fort Lauderdale-Hollywood International Airport in Florida; JFK and Orlando International Airport; and Fort Lauderdale-Hollywood Airport and Bradley International Airport in Connecticut. Between June 2022 and November 2023, there were chronic flight delays for five months in a row. The Bureau of Transportation Statistics estimates that more than 70 percent of the disruptions on these flights were caused by the airline.

“The Department will enforce the law against airlines with chronic delays or other unrealistic scheduling practices to protect healthy competition in commercial aviation and ensure that passengers are treated fairly,” Buttigieg said.

Derek Dombrowski, a spokesman for JetBlue, said in a statement that the airline has invested tens of millions of dollars over the past two years to reduce flight delays and has seen “significant operational improvements.” Mr. Dombrowski also said air traffic control problems contributed to the airline’s operational challenges in the Northeast and Florida.

Last week, JetBlue made headlines when a flight from the Turks and Caicos Islands to Boston was delayed more than 24 hours, leaving passengers stranded without accommodation.

From January to September last year, about 71 percent of JetBlue’s flights were on time, according to the Transportation Department, and the airline ranked second-to-last among the top 10 domestic airlines in on-time performance (Frontier Airlines was in last place). According to the Bureau of Transportation Statistics, more than 9 percent of JetBlue’s flights during the same period were delayed by the airline.