Southwest airlines advertised $59 flights from Atlanta to New York, Chicago and Los Angeles in October.
But, there were no seats that price, according to the department of transportation.
So the agency slapped Southwest with a $200,000 fine.
The airline was fined $100,000 for violating rules against deceptive advertising, and an additional $100,000 for violating the rule after being found guilty of an earlier infraction in 2012.
Southwest airlines said the latest violation was a result of an error in a television ad.
A Southwest spokesman says the ads were a mistake, and Atlanta was never supposed to be on the sale route.
He also says the airline honored the fare for customers who called and asked for it.