If that sounds a bit complicated, here’s the deal. When you earn “miles” using a credit card, it’s 1 or 2 miles per dollar, but most frequent flier programs give you a “mile” for each mile flown.
Delta, starting in 2015, will become the first major carrier to switch to the dollar model. You’ll get Skymiles based on the price of your ticket, and depending on your class or tier status, you’ll get more per dollar. Elite flyers in first class could get up to 13 miles per dollar, while cattle class will earn 5. The stated aim is to reward those who make the airline the most money.
For frequent flyers who get most of their miles from spending, it won’t make much difference. But one BIG difference: Delta will now join American in allowing one-way awards for half the price of a round-trip. Up to now, you could mix-and-match one-ways, but you had to book a complete trip.
USAToday provides MUCH MORE DETAIL.