Originally Posted by
aresef
Not all flights are codeshare. For me from BWI, if I wanted, I could probably book an AC codeshare BWI-ORD-YVR, but if I try to search United for, say, BWI-TYO, only UA and ANA options will pop up, not BWI-YYZ-HND.
UA and AC don't have a JV for TPAC travel. Even if there happens to be a codeshare on the YYZ-HND flight, UA might not particularly want to sell it to you when there are UA/NH options available. (UA and NH
do have a JV for TPAC).