If a $59 flight from Atlanta to Los Angeles, Chicago or New York sounds too good to be sure, that's because it is.

After falsely advertising ultra-low flight fares, the U.S. Department of Transportation slapped Southwest Airlines with a hefty $200,000 fine on Thursday.

By law, airlines are required to display the full cost of all fares, including taxes and fees. Airlines that advertise fares for specific routes must also offer a "reasonable numbers of seats" for those flights. However, when potential customers tried to book the $59 flights at the Dallas-based carrier, they were told that no seats were available on those routes, reports the LA Times.

Southwest Airlines blamed the violation on an error in a television ad script and stated that it never intended to offer the $59 fare for flights to New York, Los Angeles and Chicago.

"As soon as we became aware of our mistake, we pulled all incorrect advertisements off the air," the airline said in a released statement.

According to the Denver Post Business, the airline said it honored the $59 fare to consumers who contacted its reservations center asking for that exact price.

In addition to the fine issued on Thursday, the Transportation Department ordered the airline to pay a $100,000 penalty for violating the federal full fare advertising rule last year.

Back in October, Southwest advertised one-way flights from Dallas Love Field to Branson, Missouri, between March 1, 2013, and March 21, 2013 for only $66. However, the DOT found that no seats were made available at the advertised price during the time period of the sale. The DOT originally fined Southwest $200,000, but then cut half of the penalty since the airline agreed to "cease and desist" from violating the same rule within a one year time frame.