SSK/Cyrano - no offense in my posts, I finally believe there are more acceptations than I thought. Are you working in cargo or airports, not in airline?
I ask that because in the differents airline I know, yield always meant average fare per passenger, ie. revenue / seats sold.
I am fully aware than yield as defined above is not a perfect metric, and need to be adjusted by the aircraft capacity and the distance in order to compare performances (this is RASK/M) but what I don't understand is why you are using RPK and yield as the same metric? then why two metrics/names?
I also always considered than easyJet yields were around £60, ryanair 45€ etc and I doubt these are rpk... So maybee it's different in your companies, but I garantee you than in the 4 airlines I know quite well, yield is never a measure of the revenue per PAX KM (this is rpk) but only of revenue per seats sold.