Codesharing and airline partnerships within, between and outside global alliances

Airline partnerships with coordinated scheduling of air transport services such as alliances and joint ventures are a significant feature of the global airline industry. All advanced airline partnerships are rooted in codesharing. Therefore, we examine codeshare relations between the world's 50 largest airlines with hierarchical clustering using flight schedules data to detect airline partnership clusters of different sizes independently of memberships in global alliances. Our analysis confirms that the closest collaboration occurs within global alliances. There are also airline partnerships with extensive codesharing between aligned and non-aligned carriers, but not between airlines of different global alliances. Star Alliance appears to be the least tightly coupled global alliance, oneworld the most inclusive.