From about 10 a.m. to noon ET, some Delta fares on the airline's own website and other airfare booking sites were showing up incorrectly, offering some savvy bargain hunters an incredible deal. A roundtrip flight between Cincinnati and Minneapolis for February was being sold for just $25.05 and a roundtrip between Cincinnati and Salt Lake City for $48.41. The correct price for both of those fares is more than $400.
Trebor Banstetter, a spokesman for the Atlanta-based airline, said the problem has been fixed but "Delta will honor any fares purchased at the incorrect price."
New Department of Transportation regulations, aimed at truth in advertising, require airlines to honor any mistake fares offered.
http://accesswdun.com/article/2013/12/269256