When I arrived at MEL, my first stop was the Qatar check-in desk. I asked the agent for my connecting boarding passes from Ho Chi Minh. Unfortunately, Qatar was unable to issue the boarding passes but the agent did suggest I ask Thai to check my baggage all the way through to JFK, as the two airlines have a baggage service agreement. An agent at the Thai Airways check-in counter made a few phone calls and verified the baggage services agreement. The agent then checked my onward connections and issued luggage tags that read BKK-SGN-DOH-JFK. Finally, the Thai agent issued me my boarding cards for my Thai flights. Again to her surprise and mine a boarding card for my flight from SGN-DOH, a Qatar Airways flight, printed from her machine as well on the Thai card stock. When I arrived at JFK 58 hours later, my bag was waiting for me.
How can you tell if the airlines you're flying have a baggage service agreement or any additional agreements? It takes a bit of research. If you're flying with airlines within the same alliance, they'll likely have service agreements. But if you're traveling between two alliances like I was, your best bet is just to ask at check in or call ahead — the worst that can happen is that there's no such agreement. As TPG always says, it never hurts to ask.
