A bug in United 's ticketing system made for cheap air fares last week . But he also knew from first-hand experience that `` error fares '' -- rock-bottom fares mistakenly issued by carriers -- can sometimes be recognized as good for travel by airlines . United said it would not collect the fares , except for passengers who had already departed . New regulations say airlines must honor tickets issued in advance , once paid for .
A bug in United 's ticketing system made for cheap air fares last week . United said it would not collect the fares , except for passengers who had already departed . New regulations say airlines must honor tickets issued in advance , once paid for .