Exploring the regional hubs in the large local components
Table
7 lists the top 5 connected airports in the seven large local components called regional hubs. It also reports the cumulative proportion of airports connected to the regional hubs.
The five top connected airports of the North and Central America-Caribbean component are in the United States. They are in four different states (Illinois, Texas, Colorado, Georgia). They are the most important of major airlines in the United States. Indeed, each of these airports receives more or less 50 millions passengers per year. Hartsfield J Atlanta Airport is Delta Air Lines’ headquarter and one of its central hubs. It is one of the busiest airports worldwide, with almost one hundred millions passengers per year. The Dallas Fort Worth Airport ranks second. Located in Fort Worth, it is the primary hub of American Air Lines and Southwest Airlines. The third hub of this component, the Chicago O’Hare & Chicago Airport, is one of the main hubs of United Air Line (headquartered in Chicago) and American Air Line. Denver Airport is the fourth hub of this component. It has the largest area in the United States. Headquarter of the low-cost carrier Frontier, it is a crucial hub for United Air Lines. The second important airport in Texas, the George B Houston Airport, is this component’s fifth hub. It is one of the hubs of United Air Lines. Altogether, these first five hubs connect half of the airports in the component.
The top five hubs in the
European component are in four different countries (Netherlands, Germany, UK, Spain). These airports are the stronghold of the biggest airlines in these countries. The number of passengers ranges from approximately 70 millions to 20 millions per year. The Amsterdam Schiphol Airport is the first hub of this component. It is the largest in the Netherlands and the most critical hub of KLM. It is also a very active platform for low-cost carriers such as EasyJet, Vueling, TUI Air Lines, Corendon Dutch. Munich Airport in Germany is second. It plays an essential role for Lufthansa Air Lines and its low-cost subsidiary (Air Dolomity, Eurowings) to serve European destinations. The London Stansted Airport in the United Kingdom is the third hub of the component. It is a major airport for low-cost carriers such as Ryanair, Pegasus, Easy Jet (Dobruszkes
2006). Due to its geographical position and the high level of tourism in Barcelona, its airport is very well connected. It receives about 20 millions passengers per year. Indeed, the Barcelona airport in Spain is the fourth most connected airport. It is the primary airport of the Vueling Air Lines. Frankfurt in Germany, the fifth hub, is the main historical airport of Lufthansa. While Munich is more focused on European destinations, Frankfurt is devoted to international destinations. These five hubs allow reaching about 56% of the airports of this component. The London Gatwick Airport (132 links) in the United Kingdom, Charles de Gaulle Airport (129 links) in France, Dublin Airport (128 links) in Ireland, Düsseldorf Airport (121 links) in Germany, and Ataturk Airport (121 links) are the five other hubs. The top first ten hubs can reach 66% of airports of the component. They are the home of the leading European carriers.
The largest four hubs in the East and Southeast Asia component are in different provinces and municipalities of China. The fifth hub is in Taiwan. These airports receive tens of millions of passengers per year. The most connected, Beijing Capital Airport, is one of the busiest airports in the world, with almost 100 millions passengers yearly. The Guangzhou Baiyun airport, the second hub of this component, is situated in the capital of the provincial Guangdong in South China. It is a hub of the China Southern Air Lines, which is headquartered in Guangzhou. The Shanghai Pudong Airport, situated in East Asia, has the same degree as the Guangzhou Baiyun airport. It is a major hub of the Shanghai and China Eastern Air Lines. The fourth hub, called Chengdu Shuangliu Airport, is in the capital of Sichuan province. Serving Central-western China, it is the central hub of the Sichuan and Chengdu Air Lines. The Taiwan Taoyuan Airport is the fifth regional hub in East and Southeast Asia. Serving Taipei, it is the largest airport on the island. Together, these hubs are connected to 46,6% of East and Southeast Asia airports.
The first five hubs of the Africa-Middle East-Southern Asia component span Africa, the Middle East, and Southern Asia. Indeed, two are in the Middle East, two in India and one in Africa. The first, Dubai airport, is one of the most important airports in the world. It can handle more or less 100 millions passengers. It is the most critical hub of Emirates Air Lines. King Abdulaziz Airport in Saudi Arabia ranks second. It is the largest airport in terms of surface area. Located near Mecca, it receives many visitors from different Muslim countries. The biggest airport in India, Indira Gandhi Airport, is third. Situated in the capital Delhi, a cosmopolitan and tourist city, it receives a lot of people. The Chhatrapati Shivaji Airport, located in the megacity of Bombay, the economic capital of India, is the following hub. It is the central hub of India Air Lines. The Addis Ababa Bole Airport in the capital of Ethiopia is the fifth hub of the component. Due to its political and geographical position, it connects Africa with the rest of the world. It is the hub of Ethiopia Air Lines, the first airline serving Africa’s airports. These five hubs connect about 51% of airports of the Africa-Middle East-Southern Asia component.
Among the top five hubs in the Oceania component, three are in Australia, one in New Zealand, and one in Papua New Guinea. These airports receive less than 50 millions passengers per year. The Sydney Kingsford Smith Airport is the largest hub of the Oceania component. Indeed, located in the capital city of New South Wales in Australia, Sydney is a metropolis and touristic city attracting people coming from different countries. It is the main hub of Qantas, the largest airline in Australia. The Brisbane Airport, situated in the capital city of Queensland, is the second most connected airport in this component. Like Sydney, Brisbane is also a tourist city that receives many people from different horizons. It is the primary airport of Virgin Australia and a hub for Qantas. The third hub, Auckland Airport, is the top airport in New Zealand and the base of Air New Zealand. The Melbourne-Tullamarine Airport located in Melbourne ranks fourth. It is essential for Jetstar Air Lines, based in Melbourne and Qantas. Melbourne is also a metropolitan city that receives numerous tourists. The fifth hub of this component, the Port Moresby Jacksons Airport, is the most influential airport of Papua New Guinea. Located near Port Moresby, this airport is the largest hub of Air Niugini, headquartered in Port Moresby. These five hubs serve 48,7% of the airports in the component.
Three of the top five hubs in the
South America component are in Brazil, one in Colombia, and one in Argentina. Guarulhos G A F Montoro Airport, the first hub, is in São Paulo, the most populated city in Brazil. The busiest in Brazil (Couto et al.
2015), it is an essential airport for GOL (based in Rio de Janeiro) and ITA Air Lines (based in São Paulo). The second hub in Columbia, the El Dorado Airport, is in Bogotá, the capital of Colombia. It is the base for Avianca Air Lines. The Viracopos Airport in Campinas ranks third. It has a regional vocation in Brazil (Couto et al.
2015). It is a hub for Azul Brazilian Airlines, a low-cost airline. The Jorge Newbery Airport is the fourth hub of this component. Located in Buenos Aires, the capital of Argentina, it is a hub for the largest Argentina airline (Aerolíneas Argentinas). The fifth hub, the Presidente J Kubistschek, is in Brazilia, the capital of Brazil. It is one of the hubs of GOL and LATAM Brasil Air Lines. These five largest hubs reach around 64% of airports in this component.
In the
Russia-Central Asia-Transcaucasia component, the top five airports are in the major cities of Russia. They receive less than 50 millions passengers per year. The Domodedovo Airport, located in Moscow, is the first hub. It centralizes about 72% of the routes. Sheremetyevo Airport in Moscow and Pulkovo Airport, the main airport of St Petersburg, are tied for second. Together the two top airports in Moscow concentrate 80% of the destination of the component. Therefore, Moscow is the heart of the component and the Russian air network in particular. This result corroborates the findings reported in Tarkhov (
2017). Indeed, this paper shows that since the fall of the Soviet Union, the Russian air network is more and more centralized in Moscow. Almost all flights (regional and international) transit through this city. The Domodedovo Airport is a hub of the Domodedovo Air Lines, and the Sheremetyevo Airport is a hub of Aeroflot–Russian Airlines, the biggest in Russia. The Pulkovo Airport is the main airport of St Petersburg, the second-largest city in Russia. It is also an important airport for Rossiya Airlines. Another hub of this component is the Tolmachevo Airport, located near Russia’s major city, Novosibirsk. This airport has a regional vocation. It is an important airport for the Novaport Air Lines. Situated in Yekaterinburg city, the Koltsovo is the fifth most connected airport of this component. It is a vital hub for the Ural Air Lines, based in the same city as the airport. These hubs reach around 85% of airports in this component.
Table 8
Degree centrality in the large global component
North and central America- Caribbean | John F Kennedy | New York | USA | 62 | 1 | 9 |
Lester B Pearson | Toronto | Canada | 45 | 2 | 19 |
Newark Liberty | Newark | USA | 39 | 3 | 24 |
Miami | Miami | USA | 36 | 4 | 27 |
Los Angeles | Los Angeles | USA | 34 | 5 | 30 |
Europe | Frankfurt | Frankfurt | Germany | 106 | 1 | 1 |
Charles de Gaulle | Paris | France | 104 | 2 | 2 |
Atatürk | Istanbul | Turkey | 99 | 3 | 3 |
Heathrow | London | UK | 89 | 4 | 4 |
Schiphol | Amsterdam | Netherlands | 80 | 5 | 7 |
East and Southeast Asia | Beijing Capital | Beijing | China | 61 | 1 | 10 |
Suvarnabhumi | Bangkok | Thailand | 57 | 2 | 12 |
Narita | Tokyo | Japan | 56 | 3 | 13 |
Incheon | Seoul | South Korea | 48 | 4 | 15 |
Hong Kong | Hong Kong | Hong Kong | 47 | 5 | 16 |
Africa- Middle East- Southern Asia | Dubai | Dubai | U A E | 89 | 1 | 4 |
Hamad | Doha | Qatar | 59 | 2 | 11 |
Abu Dhabi | Abu Dhabi | U A E | 42 | 3 | 22 |
Cairo | Cairo | Egypt | 34 | 4 | 30 |
Indira Gandhi | Delhi | India | 31 | 5 | 32 |
Oceania | Sydney K Smith | Sydney | Australia | 26 | 1 | 41 |
Melbourne | Melbourne | Australia | 20 | 2 | 57 |
Auckland | Auckland | New Zealand | 13 | 3 | 96 |
Perth | Perth | Australia | 13 | 3 | 96 |
Brisbane | Brisbane | Australia | 12 | 4 | 106 |
South America | Guarulhos-G A F M | São Paulo | Brazil | 36 | 1 | 26 |
El Dorado | Bogotá | Colombia | 30 | 2 | 36 |
Jorge Chávez | Lima | Peru | 22 | 3 | 53 |
Ministro Pistarini | Buenos Aires | Argentina | 19 | 4 | 61 |
Rio G–T Jobim | Rio de Janeiro | Brazil | 18 | 5 | 69 |
Russia- Central Asia- Transcaucasia | Sheremetyevo | Moscow | Russia | 84 | 1 | 6 |
Domodedovo | Moscow | Russia | 77 | 2 | 8 |
Pulkovo | St Petersburg | Russia | 47 | 3 | 16 |
Vnukovo | Moscow | Russia | 31 | 4 | 32 |
Heydar Aliyev | Baku | Azerbaijan | 23 | 5 | 51 |
Exploring the inter-regional hubs in the large global component
We consider the large global component to extract the high degree airports. For comparative purposes, we classify the so-called inter-regional hubs in seven regions based on their local component. Indeed, an airport in a global component is also a member of a local component. Table
8 reports their coordinates and their external degree (number of links with airports outside their local component). Their global rank in the component is computed according to the decreasing order of their external degree. The global rank in their region measures their relative global position in their region. Four out of five of the top inter-regional hubs in the North and central American-Caribbean area are in the USA. These hubs are located on the coasts, closer to the other regions. The largest hub of this component is the John F Kennedy Airport, located in New York. This gateway to the United States is the busiest airport for international flights, with around fifty millions passengers yearly. It is an essential platform for American Airlines, Delta, and Jet Blue. The most important airport in Canada, the Lester B Pearson Airport, is the second-largest inter-regional hub. It connects Canada and the US to the other regions. Situated in Toronto, it is the primary hub of Air Canada. Newark Liberty Airport ranks third. This crucial hub of United Airlines serves the New York metropolitan area. Miami and Los Angeles complete the top five. These airports allow reaching the United States from South America and Asia, respectively. The top five European airports, Frankfurt, Charles de Gaulle, Ataturk, Heathrow, Amsterdam, are the primary hubs of the leading airlines in Europe, Lufthansa, Air France, Turkish Airlines, British Airways, and KLM, respectively. Note that Frankfurt and Amsterdam Schiphol airports are also among the five most important regional hubs. Charles de Gaulle Airport, the first French airport, is located in Paris, the world-leading destination in the world. Thanks to its central position, the Ataturk Airport is a vital hub where several air flights transit. Indeed, it is at a gateway for Asia, the Middle East, and Africa. The fourth inter-regional hub is London Heathrow, located in the top tourist city of the United Kingdom, London. It is the leading international airport in London.
While China dominates the regional hubs, inter-regional hubs are scattered in different countries of East and Southeast Asia. Beijing Capital Airport is the inter-regional hub. The Suvarnabhumi airport located in Bangkok, the capital city of Thailand, ranks second. It is an important hub serving local (Thai Airways and Bangkok Airways) and foreign airlines connecting to Asia, Oceania, Europe, and Africa. Narita, located in Tokyo, the capital of Japan, is a hub for Japan Air Lines and All Nippon Airways. The largest airport in South Korea, the Incheon Airport, is the fourth inter-regional hub. Located on the coast in Seoul, which receives a million tourist passengers per year, this airport is an important hub for Korean Air Lines. The Hong Kong Airport is the primary hub of Cathay Pacific and Dragon Air Lines, headquartered in Hong Kong.
The regional hubs, Dubai and Indira Gandhi Airport, are respectively the first and the fifth inter-regional hubs in the Africa-Middle-East Southern Asia area. The Hamad airport is the second inter-regional hub in this zone. This airport, located in Doha, the capital of Qatar, is a gateway to Europe, Asia, Africa, and Oceania. It is the most important hub for Qatar Airways. Abu Dhabi, the second-largest airport in the United Arab Emirates, is also strategically located. It is the primary hub of Etihad Airways. The fourth hub located in Cairo is the vital hub of Egypt Air.
In Oceania, the four regional hubs (Sydney K Smith Airport, Melbourne Airport, Auckland Airport, and Brisbane Airport) are also the inter-regional hubs. In addition, Perth Airport is an inter-regional hub. This airport, located on the coast of the capital city of Western Australia, is an essential airport for Alliance Airlines. One can see that Australian airports are the most influential in this area.
The two largest inter-regional hubs in South America (Guarulhos in Brazil and El Dorado in Colombia) are also the two largest regional hubs. The third hub, Jorge Chávez Airport, is located in Lima, the capital of Peru. It is the hub of different airlines such as ATSA, LATAM Perú Airlines. The largest airport in Argentina, the Ministro Pistarini Airport, located in the capital city of Argentina, has a vital role in international flights. It is the hub of Aerolíneas Argentinas.
In the Russia-Central Asia-Transcaucasia area, the top four inter-regional hubs are in Russia. Note that the top three are also present in the list of the top five regional hubs. The Vnukovo Airport is the fourth inter-regional airport. Located in Moscow, it is a hub for the Azur Air Lines. It corroborates the extreme centralization of the Russian air transport network in Moscow. The Heydar Aliyev Airport, located near the coast in Baku, the capital city of Azerbaïdjan, is the fifth inter-regional hub of the area. This airport is essential for Azerbaijan Air Lines.
Comparison of the regional and inter-regional hubs with the hubs of the world air transportation network
We now compare the degree centrality of the nodes in the world air transportation network with the various degree centrality measures of the components. Table
9 reports information about the top 36 airports worldwide according to their total degree (the sum of their internal and external degree). It also contains their total degree, worldwide rank, local rank, and eventually global rank. For comparative purposes, airports are classified in the seven regions identified by the local components. At first glance, one can see that the distribution among regions is not homogeneous. Indeed, Europe and the North and Central America-Caribbean areas dominate, with 29 out of 36 airports in the world’s top ranks.
Thirteen airports of the North and Central America-Caribbean component belong to the top 36 of the world air transportation network. The top five are the top five regional airports. The eight other airports include the first five inter-regional hubs. The other three airports (Charlotte Douglas, McCarran, Detroit M Wayne) are regional hubs ranked 6, 7, and 9 in the local component. In this part of the world, regional hubs are more influential than inter-regional hubs. Indeed, the first inter-regional hub ranks nine in the world network. It shows that the air traffic in the North and Central America-Caribbean zone focuses mainly on regional destinations. The rank of the regional airports in the world air transportation network can be misleading because they are not the most active in inter-regional traffic.
With 16 airports, European airports are the most numerous in the top 36 in the world network. They are also among the most influential. Indeed, the top four world airports are in Europe. The top of the ranking includes the top inter-regional and regional airports (Frankfurt, Charles de Gaulle, Ataturk, London Heathrow, Amsterdam, Munich, London Stansted, Barcelona). Five regional airports complete this list. Three are in the UK (London Gatwick, Dublin, Manchester), one is in Germany (Dusseldorf), and one is in Austria (Vienna). Note that Dusseldorf uses to be the second airport in Germany before Munich took the lead. Two airports located in Rome and Madrid are more focused on inter-regional traffic. These results suggest that European airports are more oriented towards inter-regional connections.
There are four airports from the East and Southeast Asia area in the top 36 hubs of the world air network. Two are in the top five inter-regional hubs (Beijing Capital, Incheon), and two are in the leading regional hubs (Shanghai Pudong, Guangzhou Baiyun). Remember that Beijing Capital airport, which ranks seven in the world air network, is also the region’s top regional and inter-regional airport. This repartition between regional and inter-regional hubs indicates a balanced regional and inter-regional traffic dominated by China.
Dubai is the only airport in the top 36 world air network hubs for the Africa-Middle East-Southern Asia area. Ranked 10 in the world network, it is an essential regional hub (1st) and inter-regional hub (4th).
There is no airport of Oceania in Table
9. The first airport from this region, the Sydney K Smith Airport, ranks 84 worldwide. It is also the case for South America. Indeed, Guarulhos-G A F M, the highest degree airport in Brazil, ranks 74 in the world air network.
Two airports from the Russia-Central Asia-Transcaucasia zone are in the first 36 hubs of the global air network. These airports in Moscow are the most important hubs in the region at both regional and inter-regional levels.
To summarize, Europe and the United States dominate the world transportation network in terms of centrality. The main drawback of using world air transportation to evaluate the airports’ influence is that it cannot distinguish regional from inter-regional importance. Consequently, large parts of the world are hidden due to striking regional discrepancies. The component structure allows taking into account these regional disparities. Indeed, airports at the bottom in the world network ranking, which are very influential in their region, emerge. It is the case for airports such as the London Stansted Airport, the Chengdu Shuangliu Airport, King Abdulaziz Airport, Sydney K Smith Airport, Guarulhos-G A F M Airport, and the Pulkovo Airport that are the most connected in their region. Similarly, it brings to the attention that airports, such as Suvarnabhumi, Hamad, Melbourne, El Dorado, and Heydar Aliyev, are crucial for inter-regional traffic.
Table 9
The top 36 hubs of the world air transportation network
North and central America- Caribbean | Hartsfield J Atlanta | Atlanta | USA | 212 | 5 | 1 | 43 |
Chicago O’Hare | Chicago | USA | 200 | 6 | 3 | 39 |
Dallas Fort Worth | Dallas | USA | 188 | 8 | 2 | 78 |
Denver | Denver | USA | 165 | 12 | 4 | 197 |
George B Houston | Houston | USA | 165 | 12 | 5 | 66 |
John F Kennedy | New York | USA | 160 | 14 | 15 | 9 |
Newark Liberty | Newark | USA | 152 | 19 | 10 | 24 |
Lester B. Pearson | Toronto | Canada | 147 | 22 | 13 | 19 |
Los Angeles | Los Angeles | USA | 144 | 24 | 11 | 30 |
Charlotte Douglas | Charlotte | USA | 141 | 26 | 6 | 137 |
Miami | Miami | USA | 138 | 30 | 14 | 27 |
McCarran | Las Vegas | USA | 133 | 33 | 7 | 162 |
Detroit M Wayne | Detroit | USA | 133 | 33 | 9 | 120 |
Europe | Schiphol | Amsterdam | Netherlands | 242 | 1 | 1 | 7 |
Frankfurt | Frankfurt | Germany | 241 | 2 | 5 | 1 |
Charles. de Gaulle | Paris | France | 233 | 3 | 6 | 2 |
Ataturk | Istanbul | Turkey | 220 | 4 | 10 | 3 |
Munich | Munich | Germany | 186 | 9 | 2 | 23 |
Heathrow | London | UK | 167 | 10 | 33 | 4 |
L da Vinci-F | Rome | Italy | 158 | 15 | 16 | 14 |
London Gatwick | London | UK | 157 | 17 | 6 | 45 |
Barcelona | Barcelona | Spain | 156 | 18 | 4 | 63 |
Brussels | Brussels | Belgium | 150 | 20 | 11 | 36 |
Adolfo Suárez | Madrid | Spain | 150 | 20 | 17 | 17 |
Stansted | London | UK | 143 | 25 | 3 | 46 |
Dublin | Dublin | Ireland | 141 | 26 | 8 | 101 |
Düsseldorf | Düsseldorf | Germany | 141 | 26 | 9 | 59 |
Manchester | Manchester | UK | 141 | 26 | 13 | 46 |
Vienna | Vienna | Austria | 136 | 31 | 14 | 50 |
East and Southeast Asia | Beijing Capital | Beijing | China | 194 | 7 | 1 | 10 |
Shanghai Pudong | Shanghai | China | 147 | 22 | 3 | 28 |
Guangzhou Baiyun | Guangzhou | China | 135 | 32 | 2 | 52 |
Incheon | Seoul | South Korea | 133 | 33 | 4 | 15 |
Africa- Middle East- Southern Asia | Dubai | Dubai | U A E | 167 | 10 | 1 | 4 |
Russia- Central Asia- Transcaucasia | Domodedovo | Moscow | Russia | 158 | 15 | 1 | 8 |
Sheremetyevo | Moscow | Russia | 133 | 33 | 3 | 6 |