Function-Structure Interdependence of Passenger Air Transportation: Application of a Systemic Approach

This paper presents a systemic approach that combines ideas from system science, system engineering and complex networks theory to analyze the nature of passenger air transportation. Two fundamental properties of a system are function and structure. The function of air transport is to transport passengers from origin to destination, and the structure is how this function is provided, i.e. the flight network. Finding an appropriate approach to study the interdependence between function and structure is of prime importance when investigating complex systems such as air transportation. For this task, a conceptual multi-layered network model, called the Z- model, helps in ordering different system viewpoints. The model places function and structure on different layers of interest. It also distinguishes between a latent function, an inherent internal structure and the coupled realized function-structure layers. The latter is the main focus of this paper and it is shown that this part of the system can either be understood as a bi-level network or a set of network paths. The Z- model provides a framework to interpret real world system peculiarities that includes static properties, temporal integration and airline operational relationships. The use case here is Intra-North American passenger air transport. It is found that during the last ten year, the temporal detour of passengers on markets with long travel time improved at the cost of temporal detour of passengers with lower travel time. This is in part attributed to an increase in directness and the changed collaboration behavior of airlines. An airport centrality metric that takes function-structure interdependence into account can help explain anomalies found in previous investigations of air transportation as a complex system.