Originally Posted by jacob_m

Economy extra is a separate class onboard which is sold and marketed as a separate class, hence it is not the same thing as economy plus on UA.
The only way to get there is to pay for it (buy a proper ticket or pay an upgrade fee at the airport) or hope that economy is overbooked so some people are op-uped.
As with all European carriers, SAS does not give complimentary upgrades.