Now only from booking class Y and B.
Terms and conditions- Upgrades can be issued for paid tickets with their reservations confirmed up to 24 hours before scheduled departure.
- The Star Alliance upgrade award is only valid for certain ticket fare classes.
- On Turkish Airlines flights, only Y and B fare classes in Economy Class can upgrade to Business Class.
Last edited by no_idea; May 2, 2020 at 9:46 am
Reason: Thanks to ISTFlyer; my fault. It only effects *A upgrades. Sorry.