There's a huge gotcha for TK which is that discounted business fares don't qualify for miles or status miles on many third party airlines. So I flew out MAD to BOG in paid business class on Avianca, it booked into F fare class, and didn't accrue any miles at all. On the other hand my regional flights BOG-GIG and back were booked into S class economy, and then upgraded into U I think, which did get miles and status miles. I've had similar failures to credit almost all of my *A flights, including Lufthansa in business class to Baku. Earning on TK tends to be on TK essentially if you want reasonable prices, though there are decent prices for some destinations and it's not all that difficult to earn status. It's also quite difficult to determine what booking class you're going to get, ITA Matrix helps but often you're not told during the booking process, this is also a problem potentially with FB where there are non qualifying classes for other airlines.