Originally Posted by
mooneydriver
Update on Turkish Airlines voucher upgrade availability search.
Good news: seats.aero has a fare class availability search which allows me to look for upgrade inventory which comes out of J class.
Bad news: apparently, that is not sufficient. TK uses J class for both promo business fares and voucher upgrades, and apparently there is a separate (sub)class of J for how many of those J tickets are available for upgrades. That information does not appear to be available on any GDS. TK has their own GDS called Troya (who knows why). There's an API for Troya that's available at developer.turkishairlines.com but that API is bare bones and rather useless.
Back to square one :-(
There is no J-subclass. All that is necessary is that both the married segments have J availability as well as the individual segments when you want to use an Elite plus upgrade voucher.
upgrades with miles are only available when I-class is abailable. miles upgrades have nothing to do with J-class.
Amadeus availability search returns I-class as long as tje I-fare bucket is not closed.