Originally Posted by Flying noob

It's a fifth freedom flight. It basically means that airlines not based in one country are allowed to fly to another 3rd party country.

So Turkish airlines, not based out of Paris, is allowed to fly to Bangkok.

Typically these flights are cheaper as they serve as repositioning flights.

It's one of the 9 freedoms of air if you want to read more about it (freedom #5, why it's called a fifth freedom flight).

I tried posting the wiki link but apparently I need to post more before I can link URLs