Originally Posted by
TCASTESTOK
So what exactly does TK mean? In the IATA codes TK refers to Turkish Airlines.
It’s the 2 letter code for the Denver training center. There’s lots of theories about how “TK” was chosen, but I’ve never heard anything other than speculation. Since the merger, it’s no longer “officially” TK, but at United, it’ll always be TK, just as the 737 will always be the Guppy.