Variations in hub service in the US domestic air transportation network

This paper looks at the various types of hubs that have evolved in the air transportation network in the USA. Since deregulation of the industry at the end of the 1970s, the major air carriers have expanded their networks to become more competitive, and the number and types of hubs have grown accordingly. A connectivity analysis using a traditional matrix approach is used to derive indices which are the basis for the development of a connectivity classification scheme. In addition, the various service functions of hubs are explored.     

Temporal configurations of European airline networks

The deregulation of the US domestic airline industry resulted in the reconfiguration of airline networks into hub-and-spoke systems. In contrast to the US airlines, airlines in Europe already operated spatially concentrated networks long before deregulation. This concentration at the national home-base was the outcome of bilateral traffic rights designated to the national carrier. With a few exemptions, however, most of these star-shaped networks were not coordinated in time. Transfer opportunities at most national airports only existed by accident. Only airports that were operated as gateways to Europe provided planned connectivity between intercontinental flights and European feeder services. The deregulation of the EU market stimulated a second phase of airline network restructuring. European airlines concentrated their networks by adopting or intensifying wave-system structures (‘banks’ to use the US term) in their flight schedules. This paper investigates these post-deregulation temporal concentrations in European aviation networks. The development and configuration of wave-system structures at European airline hubs is analyzed as well as the resulting transfer opportunities during the 1990s. It is found that a temporal concentration trend exists among European airlines with deregulation resulting in the adoption or intensification of wave-system structures by airlines. These wave-system structures, as well as overall traffic growth, have significantly stimulated the number of indirect hub connections. Airline hubs with wave-system structures generally perform better because of the increased indirect connectivity given the number of direct connections.     

The impact of progressive liberalization on the spatiality of airline networks: a measurement framework based on the assessment of hierarchical differentiation

There seems to be a renewed trade-off between processes of concentration and dispersal in airline networks. This development calls for a framework that allows for a systematic assessment of the overall evolution of the spatiality of airline networks. To this end, we develop an analytical framework based on a set of spatial interaction indices, which allows measuring the degree of hierarchical differentiation (i.e. dominance and connectivity) in a network. Moreover, a normalization of these indices through a systematic comparison with the corresponding values for a rank size distribution makes it possible to engage in meaningful longitudinal analyses and/or to compare the spatiality of networks with different numbers of nodes and/or links. Our framework is tested by applying it to data on air passenger flows within Europe, and its usefulness is discussed in the context of research on air traffic liberalization.     

The spatial configuration of airline networks in Europe

The deregulation of US domestic passenger aviation in 1978 resulted in the reconfiguration of airline networks into radial route systems, spatially concentrated around a small number of central airports or ‘hubs’. This paper investigates whether a similar spatial concentration trend can be observed in the European aviation network after deregulation at the airline network level. Using the network concentration index, it is demonstrated that European ‘flag carriers’ already showed a very high traffic concentration rate at the beginning of deregulation. Between 1990 and 1999, the distribution of European traffic of these carriers remained remarkably stable according to the network concentration index. A spatial concentration trend of European traffic on a small number of hubs can only be observed for some regional airlines.     

European Union-Latin America/Caribbean air transport connectivity and competitiveness in different air policy contexts

This paper discusses the factors that affect network connectivity and competitiveness in the European Union and Latin America/Caribbean air transport market. The methodology is based on detailed real origin and destination data that allow the calculation of levels of market concentration and segmentation, airport connectivity and network efficiency. The bilateral markets analyzed compare unfavourably with other inter-continental markets, even though the economic growth of the countries involved would suggest otherwise. The market is dominated by a small number of airports and airlines, and connectivity in several Latin American and Caribbean states is over-dependent on tourism. Geographic factors can partially explain the situation identified, while the impact of policy, especially as regards the fragmented moves towards liberalisation, is also discussed.     

Is spatial dispersal the dominant trend in air transport development? A global analysis for 2006–2015

The economic performance of a city or region is considered to be intertwined with its air travel capability. It is thus important for planners and stakeholders to understand the changes in the global aviation network. This study investigates the global aviation network, taking 10 years worth's OAG data from the years 2006–2015 and examines whether a spatial dispersal trend dominates the development of the aviation industry. It considers the aviation network at the airport level, and the airport–city level, which may consist of one or more airports. After clarification of the various definitions of concentration, we find that there appears a trend toward a dispersal pattern in the global aviation network at the airport level. On the other hand, there appears a slight concentration at the airport–city level. Besides, there have been some major capacity expansions at airports in the Middle East and East Asia, while the capacities of some traditional hubs in Europe and North America have become increasingly constrained since the 2008 global financial crisis. Furthermore, our study provides further observations consistent with the phenomenon of bypassing of traditional hubs, especially mega-hubs. Competition for passengers among hubs and secondary airports, especially in multi-airport cities, is discussed.     

The transformation of a legacy carrier – A case study of Turkish Airlines

This study examines the metronomic rise of Turkish Airlines into a global carrier in the period following domestic deregulation and part privatisation. Using a comparative assessment of the carrier's network and its competitive strategies during the 2003–2013/2014 period it was found that Turkish Airlines now benefits from considerable network, cost, service and brand advantages over competing European and to a lesser extent Middle-Eastern airlines. Its network operation based in Istanbul Ataturk airport enjoys strong geographic and demographic advantages, which enables it to optimise the use of its large and young short-haul fleet between a significant number of domestic and international points. This study has important implications for partially or fully state owned legacy carriers as to how to gain competitive advantages in an increasingly open and liberal airline industry.     

Evolution trends of the network structure of Spring Airlines in China: A temporal and spatial analysis

Both the sustainable development of China's economy and the deregulation of the China air transport market have acted as a spur for the halting development of low-cost carriers (LCCs) in China. To analyze the development trends of LCCs' network in China, this paper took Spring Airlines, the only LCC in China as an example. First, the winter flight plans of Spring Airlines from 2005 to 2013 were collected. Secondly, the development trends of air transport network of Spring Airlines were explored with methods of mathematical statistics and social network analysis. Additionally, the development trends were analyzed from the levels of navigable cities, air routes and air transport networks. The results show that although Spring Airlines actively launched air routes between tourist cities with non-class I airports, its network has been transformed from a star structure into a complex one with multi-hubs. The development process of the Spring Airlines network can be separated into three stages. In addition, the problems and evolution trends of its network are discussed further.     

The geographic concentrations of air traffic and economic development: A spatiotemporal analysis of their association and decoupling in Brazil

This paper examines the evolution of the geographic concentration of the Brazilian air transport network with a focus on its determinants and possible detachments from the spatial patterns of socioeconomic activity. We develop an econometric framework employing and contrasting the results of Gini, Herfindahl-Hirschman and Theil indexes, with and without normalisation to account for economic and demographic spatial dynamics. Our results suggest that the spatial dynamics of the air network and that of the country's economy and population are strongly tied for the majority of the considered determinants. However, we find suggestive evidence that the time trend after deregulation has produced some asymmetries in the evolution of these dimensions. As such, our analysis presents some implications for airline network planning and regulators, as it offers additional information to be considered for the understanding of extra-economic and extra-demographic impacts which may be inducive of significant changes in air transport markets.     

Evolution of air transport network of China 1930–2012

This paper analyzes the evolution process of the air transport network of China (ATNC) since 1930. Based on the network analysis results, the ATNC has significantly improved in connectivity based on (1) rising alpha, beta and gamma indices, (2) declining diameter and centre index and (3) decreasing average path length and increasing clustering coefficient. The network centralization index reveals a fluctuation phase before 1952, a pre-1980 centralization phase before the economic reform era, a centralization phase after the mid-1990s deregulation, and a decentralization phase between. The k-core decomposition method helps identify the evolution of core network and hierarchy of the ATNC over time. The spatial development model characterizes its structure change in six stages: (1) scattered development, (2) trunk line connection, (3) circular linkage, (4) hub formation, (5) a complex network structure, and (6) emerging multi-airport systems.     

Air deregulation in China and its impact on airline competition 1994–2012

China’s air transportation has experienced rapid growth and major reforms in the past three decades, some of which have been partially successful and are still ongoing today. The paper aims to analyze China’s air deregulation experience over the last two decades and its impact on airline competition from a geographical perspective. After the establishment of the “Big Three” in 2002, the paper reveals that there has been a trade-off between the extent of deregulation and airline competition in China because the central government has tended to strengthen the “Big Three” rather than totally open the market to private and locally owned airlines. The paper uses each airline group as the basic unit of analysis and reveals that (1) the air market has been more concentrated in the “Big Three” as a result of the process of air deregulation; (2) airline competition in over two thirds of the airports and one half of the routes has increased in the last 18 years, but the core airports and trunk routes are chiefly dominated by the “Big Three”. The peripheral airports and thin routes have been operated by private and locally owned airlines; and (3) regionally, airline competition has occurred in most airports of the eastern region, and it is more intense than in the central and western regions. But even here, competition in the eastern region has however decreased in 1994–2012. The three main contributions of the paper are: (1) the use of two measures of competition in the airline market; (2) the analysis of the historical evolution of competition; and (3) an understanding the role of the geography of competition in the Chinese airline market.     

How did COVID-19 impact air transportation? A first peek through the lens of complex networks

The current outbreak of COVID-19 is an unprecedented event in air transportation. This is probably the first time that global aviation contributed to the planet-wide spread of a pandemic, with casualties in over two hundred countries. As of August 23rd, 2020, the number of infected cases has topped 23 million, reportedly relating to more than 800,000 deaths worldwide. However, there is also a second side of the pandemic: it has led to an unmatched singularity in the global air transportation system. In what could be considered a highly uncoordinated, almost chaotic manner, countries have closed their borders, and people are reluctant/unable to travel due to country-specific lock-down measures. Accordingly, aviation is one of the industries that has been suffering most due to the consequences of the pandemic outbreak, despite probably being one of its largest initial drivers. In this study, we investigate the impact of COVID-19 on global air transportation at different scales, ranging from worldwide airport networks where airports are nodes and links between airports exist when direct flights exist, to international country networks where countries are contracted as nodes, and to domestic airport networks for representative countries/regions. We focus on the spatial-temporal evolutionary dynamics of COVID-19 in air transportation networks. Our study provides a comprehensive empirical analysis on the impact of the COVID-19 pandemic on aviation from a complex system perspective using network science tools.     

Business connectivity,air transport and the urban hierarchy: A case study in East Asia

This paper explores the effect of business connectivity between cities on their air traffic connections, and in turn on their place in a region's urban hierarchy. Its focus of attention is East Asia, where economic development is underpinned by a complex set of international flows of trade and investment. Business connectivity is a key part of these flows. The research incorporates a measure of business connections in a regression model that previously relied on GDP per head, population and distance to account for international air links. Results confirm that business connectivity is a more important influence on the level of international air links within East Asia, and plays a major role in explaining the changes in city rank over time. The paper concludes with suggestions that possible incorporation of domestic air travel (itself larger than the intra-regional flows in this region) could enrich the insight of this approach.     

The effect of LCCs operations and scheduled services deregulation on air charter business in Japan

Recent aviation deregulation is producing structural changes within leisure industries in many parts of the world. This paper reviews the development of low cost carriers (LCCs) and assesses its effects on both of domestic and international charter markets in Japan since 2007. Furthermore, this paper analyzes the effect of scheduled services deregulation on international tourism to Japanese regional areas in relation to charter services. The results suggest that in the domestic market, LCC operations have seldom impacted charter traffic due to the differences in target markets and routes. In the international market, LCCs launched scheduled services to Japan but mainly on high demand routes. The deregulation of scheduled services led to a passenger shift from charters to newly scheduled flights and a concentration of tourist arrivals in regional centres. It also led to a decline in international tourist arrivals in some remote destinations. This paper indicates a current trend in which charter business is still an important sector in aviation and leisure markets.     

High-technology employment and hub airports

Deregulation of the US domestic air transport market in 1978 brought significant benefits to air travelers. The scheduled airlines have been given the freedom to improve their efficiency through being able to adopt efficient network strategies and more effective operating practices. This study examines empirically the advantages enjoyed by those passengers having access to a major hub airport. These often include more direct services, more frequent services and a wider range of interconnecting destinations. We seek to examine the benefits that local urban areas enjoy as the result of a major airline selecting the region as the fulcrum point for its hub-and-spoke services.     

Comparing spatial concentration and assessing relative market structure in air traffic

Traffic distributions of air traffic and their concentration have been measured through Gini, an index that contrasts in many ways with other more established ones, such as Herfindahl's. This research is extended in the sense that it perceives spatial concentration in air transport as an aggregate of complex networks that are subject to multiple constraints, such as geopolitics or technology. We propose a multi-layered analytic approach where network operators are economic agents that behave in strategic ways. It allows for comparing air traffic between airports in Europe with that of the US and, in particular, introduces a normative component by isolating patterns in airlines' strategies that coincide with more or less welfare-oriented degrees of spatial concentration in light of the above constraints.     

Greek domestic air transport–industry and policy developments From post-World War II to post-liberalization

The aim of this paper was to examine the developments in the Greek domestic air transport market which have most recently been affected by the liberalization process in the EU towards the single aviation market. Liberalization of the Greek domestic market was profound, ending 35 years of Olympic Airways complete monopoly on all air transport activities. Developments include new privately owned airlines, inter-regional routes, lower fares in real terms on routes with competition, innovation, improved services and wider consumer choice. Increased competition stimulated demand in the domestic market that reached record levels achieved in the mid-1980s. Market consolidation started in late 1999.     

Estimating the impact of COVID-19 on air travel in the medium and long term using neural network and Monte Carlo simulation

The COVID-19 pandemic has had a substantial impact on the airline industry. Air travel in the United States declined in 2020 with significantly lower domestic and international flights. The dynamic change and uncertainty in the trend of COVID-19 have made it difficult to predict future air travel. This paper aims at developing and testing neural network models that predict domestic and international air travel in the medium and long term based on residents' daily trips by distance, economic condition, COVID-19 severity, and travel restrictions. Data in the United States from various sources were used to train and validate the neural network models, and Monte Carlo simulations were constructed to predict air travel under uncertainty of the pandemic and economic growth. The results show that weekly economic index (WEI) is the most important predictor for air travel. Additionally, daily trips by distance play a more important role in the prediction of domestic air travel than the international one, while travel restrictions seem to have an impact on both. Sensitivity analysis results for four different scenarios indicate that air travel in the future is more sensitive to the change in WEI than the changes in COVID-19 variables. Additionally, even in the best-case scenario, when the pandemic is over and the economy is back to normal, it still takes several years for air travel to return to normal, as before the pandemic. The findings have significant contributions to the literature in COVID-19's impact on air transportation and air travel prediction.     

Inter-urban competition and air transport in the deregulated era: The Nashville case

American cities are acting in a competitive environment as a result of forces like economic restructuring, capital mobility, and state devolution. Since the late 1970s, the federal government has dismantled the spatial boundaries of investment through the deregulation of several important sectors of the economy, including the airline industry. Transportation geographers have investigated how deregulation allowed airlines to develop a hub-and-spoke system. However, post-deregulation airline development has yet to be approached from the perspective of urban entrepreneurialism. Another layer of inter-urban competition has been added through new geographical patterns of airline investment, and capturing hub status through airport development may be especially valuable for mid-size cities. Most large cities have hub status, while small cities have no realistic chance of becoming major players in the air transportation network, thus making the hub an opportunity for mid-size cities. A case study of Nashville, Tennessee illuminates the strong local emphasis on airport expansion in the deregulated environment. Local business and government have been active and innovative, although not always successful, in policies that improve Nashville’s accessibility and position in the urban hierarchy.     

Connectivity to international markets: A multi-layered network approach

Improving connectivity for freight movements between countries is increasingly a topic at the centre of the international trade and transport policy agendas. In spite of this, a method to asses a country's degree of connectivity to its international markets for freight is still missing. To close this gap, this paper proposes a multi-layered network approach that enables the assessment of: (i) the different factors that influence connectivity to international markets; and (ii) the extent to which a country's connections matter for its international trade activities. The international trade network and its ‘support network’ are analysed using network theory. The approach proposed is applied to the Americas, a region the relevant literature has not specifically focused on yet. It is expected that a comprehensive understanding and assessment of the determinants of connectivity for freight will contribute to guide and design more effective policies to remove barriers to international trade flows.