Airline Network Structure: Motifs and Airports’ Role in Cliques

The air transport system can be considered to be a complex network with airports as vertices and direct flights as edges. Research in this area contributes to the optimisation of the airline network and the sustainable development in transportation. This study chose Air China as an example to discover the dynamics of the airline network topologically. Serving as a critical agent of social and economic connections between cities, the airline network structure evolves over time. However, Air China maintains its multicentric and hierarchical structure and forms a mature point-to-point network with codeshare partners. This research also extracts key players at the airport level and investigates the topological structure of highly connected cliques. The results show that the combination of airports in the cliques may be affected by the airline capacity, traffic rights and interline cooperation. Meanwhile, smaller airports appear more often in cliques than hub airports, which can be interpreted and justified with slot limits at mega-airports. The weighted clique percolation method provides new insights to detecting overlapping communities, which can be characterized by geographical constraints. The shared vertices in the combined codeshare network indicate the possible hub shifting in the constantly changing aviation sector.