The problem with this is that people are self sorting. Only the people who intend to fly a lot will buy this. The airline loses money because there is a disparity of information. You know in general how much you will fly, whereas the airline only knows averages. This is very similar to Bill Clinton's Pay off college loans with percentage of 20 years' income program. That didn't work because people had general idea's about their future career path. So, a future government worker may elect to use it, whereas a future investment banker will not.