On Friday, the government announced that a fine of $1.1 million will be against United Airlines as a result of more than a dozen tarmac delays that left passengers stuck on the ground for hours, in some cases without working lavatories, according to NBC News.

The delays took place the O'Hare International Airport in Chicago on July 13, 2012, where severe thunderstorms and lightening caused planes to be grounded along with several ramp closures.

Rules imposed by the U.S. Department of Transportation (DOT) prohibit U.S. airlines from allowing domestic flights to remain on the tarmac for more than three hours at U.S. airports without providing passengers with an opportunity to exit the plane. However, 13 United and United Express planes exceeded that three-hour limit the day of the storm, the government said.

While some of the planes went over the limit by only two minutes, others exceeded it by more than an hour, with lavatories not working on two of the flights during part of the wait. Over 900 passengers were impacted by the delays without being given an opportunity to deplane, according to the DOT.

"It is unacceptable for passengers to be stranded in planes on the tarmac for hours on end," Anthony Foxx, the Secretary for the U.S. DOT, said in a statement. "We will continue to require airlines to adopt workable plans to protect passengers from lengthy tarmac delays and carry out these plans when necessary."

United Airlines had a contingency plan in place for tarmac delays, but according to the DOT, the airline didn't implement that plan, and they also found the plan to be inadequate.

United Airlines told the government that it seeks to prevent tarmac delays whenever possible, according to the DOT consent order that outlines the fine.

"We are committed to complying with the tarmac delay regulations and we continue to improve our procedures while maintaining the safety of our customers and co-workers," Mary Ryan, the spokeswoman for United said in a statement to NBC News.

The airline won't actually have to pay the fine, however, as less than half of the penalty, $475,000, is due within 30 days, but the rest of the fine is credited to United Airlines, including a credit of $185,000 for compensation the carrier paid to passengers and another $440,000 for the cost of improvements that United plans to make to O'Hare airport.