What are airline alliances?

As extensive as some of the airlines’ networks have recently grown, there are still many city-pairs, travel between which will inevitably require a change of carrier. I travelled regularly on one such route during my graduate school years. At that time, no single airline could take me from Kyiv, Ukraine (this, not Kiev, is the correct Ukrainian spelling of this city's name) to Tucson, Arizona. I could, instead, travel to Phoenix – British Airways could take me there all the way from Kyiv with an overnight stay in London, and Tucson is only two hours’ drive from Phoenix Sky Harbour Airport. But when I chose to travel to or from Tucson, I had to switch airlines along the way. That is when I first learned about airline alliances, codesharing, and other interesting practices. I ended up writing a good chunk of my doctoral dissertation on this very topic.

The jargon for a trip requiring a change of operating carrier is an interline trip. Interline trips can be tricky for both the passenger and the airlines involved. For the airlines, there are two main issues: how the revenue is shared, and who is responsible for getting the passenger and their luggage to the destination in case that interline connection does not go smoothly. The passenger will of course worry about missed connections, and hope that the luggage will show up at the destination (sometimes the passenger will have to collect the luggage when making the connection). The passenger's biggest worry is of course being stuck at an intermediate airport with no airline willing to take responsibility for his or her onward journey – something that nearly happened to me on my very first trip to the United States.

Interline trips existed before the age of codesharing, alliances and joint ventures. Furthermore, passengers still successfully interline between carriers outside alliances, as well as between airlines belonging to different alliances. Airlines have defined fares they will charge other carriers for accepting such interline passengers. International Air Transport Association (IATA) operates a clearing house that handles financial transactions relating to interline passengers, making sure that everyone gets paid their due.