Originally Posted by
AS Flyer
It's only fee free if the same class of service is available and you meet the same fare restrictions. Otherwise, there isn't a "fee" per se, but you do have to pay.
WN and AS fees are the same 60+ days out. Both you can change for free, but if the new ticket is more, or less, you either pay more or get a credit. Nothing really to do with the class of service, just the new ticket price.
But Alaska has a SDC (same day confirmed) fee of only $25, vs whatever the fare difference would be switching if switching WN flights the same day. Generally for tickets booked in advance, the new fare on WN is going to be much more than $25.