(CBSDFW.COM) – American Airlines was fined by the Federal Aviation Administration for failing to comply with federal rules on long tarmac delays.

Reuters reports the Fort Worth-based airline was fined $1 million for violating rules that prohibit domestic flights from staying on tarmacs for longer than three hours without letting passengers get off the plane. The rules also apply to international flights but for four hours.

Delta Airlines was also fined $750,000 for the same violation, according to Reuters.

In a statement, American Airlines said:

“While these delays were the result of exceptional weather events dating as far back as 2015, American takes its responsibility to comply with Department of Transportation rules seriously. The safety and well-being of those who choose to fly with us is always our top priority and we regret any inconvenience caused to our customers whose travel plans were disrupted. We apologized to those who were impacted by these tarmac delays and have put procedures in place to help better accommodate our customers when inclement weather occurs.”

American was credited back $450,000 for offering compensation to passengers affected by the delays.