If an airline is in IATA, BA may have some sort of interline agreement with it. But many airlines are not part of IATA, especially low-cost airlines, who think membership is one of the costs they can avoid. It is true that, for historical reasons, BA and VA have an interline agreement on some lines. BA and Virgin have an interline agreement. Ba accepts luggage if it is on 1 ticket. If Travelocity tried to compile 2 tickets, you won`t be lucky. You must collect your baggage after the end of your Southwest flight and drop it off for the next part of your trip to Hawaiian. There are also interline agreements that consist only of the exchange of cargo and not passengers. The list of interline partners is not necessarily important. For passing cheque services, BA requires that journeys be booked together. If this is the item, you need to use the service.
If not, you won`t (even on BA). What this means for customers if they are not accepted by the registration: do not use a minimum connection time. You must collect your luggage on the ticket upon arrival. They must check in again at the airport of departure of their trip. A different amount of free baggage may apply to each flight. If the arrival flight is delayed, they are only entitled to normal compensation (i.e. EU legislation) for the delayed flight. They cannot claim the costs of their subsequent flight if the arrival flight is delayed. Well, they had to do this for a while after BA took over the IMC, and there have been a lot of UK VS routes and vice versa that have already been booked with ex-IMC flights. This probably consumed a whole decade of interline luggage. If you are booked on separate tickets with another airline that connects to Hawaiian Airlines, please take your baggage from the luggage storage at your connecting airport and check again with a Hawaiian Airlines agent. At this time, baggage charges may be incurred.
In the cases mentioned below, when more than one ticket is presented, Delta will continue to drop off baggage from the point of departure to the destination. And this has been the case for ages. Given BA`s dominant position at Heathrow and its joint venture with AA, they would not dare to remove the interconnection with VS for at least UK domestic and short routes in Europe. I expected to see some kind of big “NOPE!”, but instead, the interconnection of luggage is not mentioned at all. As suggested in the USBT article above, you can do this yourself by searching for flights on EF or KVS that, in turn, are looking directly for a GDS, or by using the website of an online travel agency like Expedia. If the combination of BA and the other airline appears on a single route, there is an interline agreement to that effect. Not all airlines have interline agreements. And sometimes airlines argue and suspend their deals just to pick them up later (normally) after the dispute has subsided. But VS and BA have an active agreement on online luggage at that time.
A complete list of interline partners for an airline as large as BA will not be publicly available on the airline`s website (e.g. B BA). The list contains fierce rivals like Virgin Atlantic and BA will not solicit them. If there is no agreement between the two airlines, I cannot imagine how the luggage could be transshipped. Line-spacing agreements and alliances are separate points. Even if an airline is in another alliance, that doesn`t mean it doesn`t have interline agreements. . . .