If you are completely separated, with your first step in an airline like Turkish, it should not be difficult, but you have to ask for it. You may want to arrive early at your departure airport, as the check-in agent must be able to print Interline compliant trailers and bring your luggage to your final destination. BA are members of Oneworld and Aegean are members of star alliance. This means they have an interline agreement, and any competing travel agency, not shonky Online Co, should be able to book you a passing ticket. Although BA and Aegean are not partner airlines, they do have interline agreements. This means that a competent travel agency is able to compile a valid transit ticket and get a passage ticket, the luggage is checked. Many airlines have interline agreements with other airlines, which is a very fundamental partnership. This means that Airline A can issue tickets to travel with Company B and drop off luggage up to Company B. For the most part, you can buy a ticket through Company A with flights with Airlines A and B, but this is not always the case when the airlines have not concluded specific agreements. In a joint venture, airlines operate in the same way as possible, which means they evaluate their flights in the same way, share revenue, share strategies and risks, normalize the embarked experience, offer the same benefits to passengers, offer similar schedules and connections, can offer more benefits for frequent travelers, etc. As part of a joint venture, all airlines generally discuss and agree on everything related to that joint venture, from operations and flights to elite benefits, etc. Interline agreements also cover irregular operations – an airline can reallocate a passenger to another airline with which they do not normally cooperate. Therefore, interconnection is one of the most fundamental types of airline partnerships.
If an airline does not have partners, it is likely that they will not succeed, because no airline is able to go wherever passengers want to go. . . .