Originally Posted by dvs7310

Yes, AA (or any other ticketing airline / travel agent) can book CAI-DOH as your first segment. That's just a strange limitation of the OW online tool.

You're also correct that QR doesn't offer much D availability ex-CAI, it offers precisely zero to be more accurate. Most middle east flights are marketed as First Class, so you need A on those segments instead of D. (Also grants you access to the Al Safwa lounge in DOH).

When ticketing ex-CAI or ex-OSL, just anecdotally, in addition to BA having high YQ, MH, CX, and QF tend to as well. You may reduce those by booking as codeshares but note CX can't carry an AA code for TPAC due to government restrictions since CX is (or was) overflying Russia.

BTW, ex-CAI isn't cheap anymore, it's quite a bit more expensive than other points of origin now. OSL and ex-Japan are currently cheapest, followed closely by ex-Pakistan, then India and Sri Lanka.