Join Date: Nov 2018
Location: Istanbul, Turkey
Programs: TK Elite Plus,BAEC GGL,ITA Executive, AFKL Gold,QR Gold,HH Diamond,Bonvoy Gold,ALL Gold
Posts: 14,186
For upgrade inventory, you need to code F bc=j in ITA Matrix.
J fare class availability in TK is required for mileage upgrades.
F bc=s would give you the cheapest Economy fare that you are able to upgrade.