One most airlines, you'll earn miles based on the class of service
purchased and not the class of service
flown.
Bought a coach ticket and upgraded? You probably won't get a "class of service bonus" for flying C or F.
But you will get miles for the flight.
Alaska, for instance, used to give miles based on class of service
flown. AS flyers sure miss that one!
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View from the Wing: A blog about Free Miles and Free Markets