Originally Posted by
MikeMpls
I suspect the mileage estimates are the output from some generic great circle calculator. The actual mileage credited can even vary slightly by airline.
I always thought they just read the odometer on the plane.
It's one thing for the mileage on a codeshare flight to be off a bit. But for NW metal flights booked on nwa.com, there's no excuse for the discrepancy.