Evolution of the international air transportation country network from 2002 to 2013

In this research, we analyze the evolution of the international air transportation country network from 2002 to 2013 with two perspectives: The network’s physical topology and the functional network with traffic information. Our analysis shows that the network is scale-free and has the small-world property. The evolution of triadic properties suggests that the network gears towards symmetric, transitive closure. We find that United States, Great Britain, and France are critical from both perspectives; Surprisingly, South Africa is particularly critical from topological point of view. Furthermore, topological and functional criticality are highly correlated to the GDP of a country.     

Political risk assessment on air logistics hub developments in Taiwan

Political risk assessment has long been practiced by multinational corporations, but has been rarely used for air performance reviews. This study is a political risk assessment of the development of an air logistics hub in Taiwan, and thus examines the factors leading to physical property losses of air carriers based at the hub. It utilizes a checklist and a brainstorming session to identify risk factors, a 5×5 risk matrix to undertake a qualitative risk survey, and an analytical hierarchy process to assess the risk. The study concludes that micro- and macro-factors are approximately of equal importance to the development of an air hub in Taiwan. Issues relating to inland vehicle parking, air logistics infrastructure developments and the cross-strait relationship appear to be particularly crucial.     

COVID-19 pandemic and air transportation: Successfully navigating the paper hurricane

This paper aims to analyze and understand the impact of the corona virus disease (COVID-19) on aviation and also the role aviation played in the spread of COVID-19, by reviewing the recent scientific literature. We have collected 110 papers on the subject published in the year 2020 and grouped them according to their major application domain, leading to the following categories: Analysis of the global air transportation system during COVID-19, the impacts on the passenger-centric flight experience, and the long-term impacts on broad aviation. Based on the aggregated reported findings in the literature, this paper concludes with a set of recommendations for future scientific directions; hopefully helping aviation to prepare for a post-COVID-19 world.     

Liberalization and changing spatial configurations in Nigeria’s domestic air transport network

In realization of the increasingly important role played by air transport, the Nigerian government followed the global trend of deregulation in reforming its domestic airline industry in 1985. Some of the effects of deregulation have been consistent with observed trends in other countries but others have been quite different. The abandonment of less profitable routes in the short term as well as the unfolding core-periphery structures following the emergence and dominance of certain core control centers replicates what obtained in the United States. However, evidence from literature suggesting that liberalization in practice has often resulted in the rising concentration of connectivity in a limited number of nodes and links rather than in its dispersal over the network at large does not hold yet in Nigeria’s domestic air network. This paper shows that the shifting balance between concentration and dispersal in Nigeria’s domestic network is generally skewed towards dispersal. Passenger traffic is more dispersed among nodes as gleaned from diminishing standard deviation values with increasing number of nodes. Generally speaking, overall connectivity also tends towards more evenness in the network since deregulation.     

An analysis of essential air service structure and performance

The US federal Essential Air Service program was established to subsidize air service to communities unable to retain commercial carriers after airline deregulation in 1978. In this paper, the subsidized service between program communities and commercial hub airports is investigated relative to several Essential Air Service planning objectives. Specifically, observed community hubbing activity is compared with that modeled to minimize hub access cost and maximize community accessibility within the commercial air transport system. Results highlight trends in system performance relative to these planning objectives and indicate that significant potential exists for enhancing the efficiency of the program in light of limited resources.     

Travel and tourism competitiveness index: The impact of air transportation,railways transportation,travel and transport services on international inbound and outbound tourism

The objective of the study is to examine the impact of air transportation, railways transportation, travel and transport services on international inbound and outbound tourism in a panel of 19 tourists - oriented countries, over a period of 1990–2014. By applying principal component analysis, the study constructs travel and tourism competitiveness index for inbound and outbound tourism. The main constructs of inbound tourism index include international tourists' arrival, tourism receipts, receipts of passengers' transports items and travel items while the constructs of the outbound index include international tourists' departure, tourism expenditures, and expenditures for passengers transport and travel items. The result of panel Fully Modified OLS (FMOLS) regression shows that the presence of air transportation, railways transportation, and trade openness positively affect inbound tourism index, while travel and transport services negatively affect tourism competitiveness index. The causality results confirm the bidirectional relationship between inbound tourism, air transportation, railways passengers carried, trade openness and travel and transport services, while there is a unidirectional causality running from inbound index to railway goods transported, from air transport freight to trade factor, and from travel services to air transport freight. Outbound tourism index confirmed the bidirectional causality relationship with air transportation, railways transportation, and travel and transport services, while the causality running from outbound index to trade factor, from air transport passenger carried to travel services, and from railway goods transported to trade and transport services, which support the unidirectional causality relationship between them. The variance decomposition results show that air transportation freight is the contributor that largely influences inbound-outbound tourism, while railways passengers carried and trade openness has the least share to influence inbound and outbound tourism index for the next 10-year period. The impulse response function indicates that air transportation, railways transportation, trade openness and travel services will positively impact on inbound truism while travel and transport services will positively affect outbound tourism for the next 10-year period. The study concludes with the importance of transportation sector that deem desirable to promote tourism worldwide. The concentration of different modes of transportation including air transportation, railways transportation, and travel and transport system would helpful to advance international tourism.     

Airline mergers and their effect on network structure

The Airline Deregulation Act of 1978 introduced high-level competition into the US domestic industry. The resulting network changes have created a deluge of research, largely focused on the hub-and-spoke structure. Over 15 years have passed since deregulation, and the industry still appears somewhat unsettled. Recent concerns of domestic carriers include downsizing of some hubs, and discussions of further consolidation of operations. Mergers may be the answer for airlines with shrinking markets within the US transportation system. This study examines the effect on network structure created by the merger of two carriers from the perspective of hub structures, accessibility and geographic coverage.     

Challenges to domestic air freight in Australia: Evaluating air traffic markets with gravity modelling

With two of the busiest air traffic corridors globally, Sydney-Melbourne (SYD-MEL) and Sydney-Brisbane (SYD-BNE), very liberal open skies agreements, and the world's most isolated large city in Perth, air freight in Australia should be destined for substantial growth, but has in contrast to other regions such as the US not yet materialised. This paper identifies challenges surrounding domestic air freight markets in Australia and compares the provision of road vs air freight services utilising gravity modelling methods. Our findings suggest the impedance of domestic air freight services in Australia is greater for regional areas between the primary cities (such as Canberra, between Sydney and Melbourne) than remoter areas (such as Cairns in Northern Australia). Our models show further that in addition to distance, air freight capacity on any of our analysed routes is despite being demand-pulled in terms of GDP dependency significantly attuned to factors at both the origin (in particular domestic trade capability, i.e. manufacturing and logistics) and destination.     

2-Stage stochastic programming approach for hub location problem under uncertainty: A case study of air network of Iran

In this paper 2-stage stochastic programming has been developed for formulating stochastic uncapacitated multiple allocation hub location problem. This problem is studied under three cases. The first, stochastic demand, the second, stochastic transportation cost and the third, integrated stochastic, which is compounded of first and second cases. A case of air network in Iran is used to evaluate proposed formulations and computational results obtained by GAMS are presented. The results show that considering uncertainty into formulation could cause in different solutions.     

A strategic approach to improve sustainability in transportation service procurement

This paper focuses on the procurement of full truck-load transportation service with the view to ensuring sustainability in transport logistics. The carrier assignment problem (CAP) involved in truck load contract auction is studied using a complete enumeration method and heuristic approach. Performance of both methods is compared in terms of solution quality and computational time based on the results of sample problems considered. Also, the impact of combinatorial bidding on reducing empty haul in real world case is analyzed and environmental sustainability is achieved through reduction in carbon foot print.     

Algebraic connectivity maximization of an air transportation network: The flight routes’ addition/deletion problem

A common metric to measure the robustness of a network is its algebraic connectivity. This paper introduces the flight routes addition/deletion problem and compares three different methods to analyze and optimize the algebraic connectivity of the air transportation network. The Modified Greedy Perturbation algorithm (MGP) provides a local optimum in an efficient iterative manner. The Weighted Tabu Search (WTS) is developed for the flight routes addition/deletion problem to offer a better optimal solution with longer computation time. The relaxed semidefinite programming (SDP) is used to set a performance upper bound and then three rounding techniques are applied to obtain feasible solutions. The simulation results show the trade-off among the Modified Greedy Perturbation, Weighted Tabu Search and relaxed SDP, with which we can decide the appropriate algorithm to adopt for maximizing the algebraic connectivity of the air transportation networks of different sizes. Finally a real air transportation network of Virgin America is investigated.     

Theoretical framework of systems design for the air transportation system including an inherently quantitative philosophy of scenario development

This paper provides an overview of an inherently quantitative scenario philosophy for systems analysis and innovative concept design in the context of the Air Transportation System (ATS). A general perspective of the ATS is visualized in an “atomic model” with surrounding external scenario factors and the aircraft as the key connecting element between the main stakeholders: manufacturers, airlines, air navigation service providers (ANSPs) and airports. An iterative waterfall model is presented, which serves as a mental model of integration and decomposition over cascades of levels of detail from global scenario level to a single technology. The difference between classical scenario technique and a quantitative, yet participatory methodology of developing scenarios for the ATS is described. In order to integrate and decompose over a large span of levels of details, concept design and synthesis is as important as analysis. Further, quantitative scenario development may be considered as the synthesis of a skillful manipulation of a model deck. Scenario Gaming can be a method to simulate the settlement on requirements of complex socio-technological systems with multiple stakeholders and conflicting perspectives under radically changing boundary conditions. Scenario thinking can be an innovative and explorative instrument of participatory futurology, if not reduced to a mere “input for a tool chain”.     

Regulation in the air: price-and-frequency caps

In spite of deregulation on the air-transportation markets, many connections are still operated by a single operator on regional markets, in particular in Europe. Evidence thus calls for some regulation in this industry. There is, however, a great concern for the (possibly negative) consequences of price regulation on the quality of services. We argue that both aspects should be considered jointly and propose a mechanism for the decentralization of the optimal structure of services. The regulatory procedure is based on the sole book-keeping data and requires the regulator to use only an estimate of travellers’ average value of time.     

Air transportation and urban-economic restructuring: competitive advantage in the US Carolinas

The theoretical agenda of this paper is to bring airports and airline operations more squarely into the mainstream of the urban and regional development literature. The paper examines the spatial and temporal patterns of air passenger flows by airport in the US Carolinas. An emphasis is placed on articulating the linkages that exist between airport operations at the local level, the structural composition of the regional economy, and the competitive strategies of the airline industry. Particular attention was paid to administrative and auxiliary employment levels because it is a knowledge-based producer service that tends to seek out markets that offer high levels of air service connectivity to other places. A major finding in this paper is that those US Carolina airports that experienced significant gains in air passenger volume (e.g., Charlotte and Raleigh-Durham) tended to experience comparable gains in the employment levels of administrative and auxiliary workers, particularly in the manufacturing sector.     

Relay network design in freight transportation systems

This paper provides techniques, heuristics, and algorithms for the location of a minimal number of relay points on a highway network that satisfies the driver-distance constraint––a driver leaving a distribution center does not travel for more than t miles before which he/she returns back to the originating point or rests before moving on further. Straight Route and Detour versions are considered. Empirical evaluations of the proposed heuristics on road networks are performed. The results indicate that the Straight Route version is computationally efficient but locates a larger number of relay points than the Detour versions.     

Impacts of high-speed rail on domestic air transportation in China

This study investigates the impacts of high-speed rail (HSR) on domestic air transportation in China using a new comprehensive modeling framework utilizing both demand and supply perspectives. For the first time the assessment was conducted using an improved panel regression model by taking into account of the detailed opening schedules of various HSR services during the period 2001–2014. The research findings reveal that the deployed HSR services have a significant substitutional effect on domestic air transportation in China, but the effect varies across different HSR routes, travel distance and city type. Specifically, the research found a decrease in domestic passengers of 28.2%, in flights of 24.6% and in seat capacity of 27.9% after the introduction of HSR services. The impacts are found much stronger among those air routes that connect major hub within a distance range of 500 to 800 km. The uneven nature of the impact can be seen in the different experiences of selected cities. For example, air travel declined approximately 45% after commencement of the Wuhan-Guangzhou HSR, whereas it fell by 34% after the opening of the Beijing-Shanghai HSR.     

Multi-period hub location problems in transportation

Many transport service providers operate on hub-and-spoke network structures. Major operators may have several dedicated hub facilities that are leased for a time horizon rather than being owned or constructed. For a given discrete planning horizon, service providers must decide on the location of the hub ports (i.e. terminals), the period when the lease contract starts, the period when the existing contracts must be terminated and the flow routing over the entire planning horizon so as to minimize the total operational cost. Thus, we propose a mathematical model for a Multi-period Uncapacitated Multiple Allocation Hub Location Problem with Budget Constraint. The proposed model incorporates several features of practice, particularly from maritime and land transport practices. We also propose a meta-heuristic solution algorithm that produces high-quality solutions in a reasonable amount of time. By exploiting the decomposable structure of the model, we extended a Benders decomposition approach by proposing several improvements. Extensive computational experiments confirm the efficiency of the proposed methods and also show its limitations.     

Aircraft routing for on-demand air transportation with service upgrade and maintenance events: Compact model and case study

This paper addresses a problem faced by airline companies that offer on-demand flight services. Given a list of flight requests, the company has to assign its aircraft to these requests while minimizing operational costs. The main issue in this planning process involves the positioning of aircraft when they are not available at the airports of customer departure. The cost of this positioning should be as low as possible, as the customers’ expenditures are proportional to the requested flight hours only. We propose a compact optimization model to support decision making in this situation. It takes into account the mandatory aircraft maintenance events and the possibility of flight upgrades according to the their impact on the operational costs. One important and novel feature of this model is that it allows the anticipation or postponement of the beginning of flights and maintenance events within a given tolerance, giving more freedom to the decision making process. This research is motivated by a case study carried out with a fractional management airline company that operates in European and Asian countries. Computational experiments using real-life data collected from the company show that the proposed model can be solved quickly using general-purpose optimization software, including open-source alternatives. The results indicate that the obtained solutions lead to significant reductions in the operational costs and hence can be used in practice for effective decision making.     

Robustness of the air transport network

This paper presents a methodology for the detection of critical airports (those whose isolation would cause the largest losses in network connectivity) in the global air transport network (ATN), based on simulating an attack on selected ATN airports using different adaptive selection criteria. The performances of several node selection criteria are compared, together with a new criterion based on Bonacich power centrality. The results show that most critical airports can be detected with an adaptive strategy based on betweenness centrality. The detection of such airports may help the development of contingency plans to develop an appropriate response to any airport closure.     

Embedding economies of scale concepts for hub network design

We explore the idea of endogenous hub location on a network. In contrast to much of the literature, we propose that hub networks may emerge naturally out of a set of assumptions and conditions borrowed from equilibrium traffic assignment. To this end, we focus on applying a nonlinear cost function that rewards economies of scale on all network links. A model is presented and implemented in a GIS environment using both a 100-node intercity matrix and several synthesized interaction matrices. We compare solutions for different assumptions about network costs, and visualize the results. We find that under discounted conditions, network flow is re-routed to take advantage of the cost savings for amalgamation and that several cities emerge as centers through which large amounts of flow pass. Larger cities such as Los Angeles, New York and Chicago serve gateway functions. We also find that smaller cities such as Oklahoma City, Pittsburgh, Indianapolis, and Knoxville serve major gateway functions because of their locational advantages. Our paper should be of interest to the planner of a surface transportation system, or those interested in nodal concepts such as gateways and transport geography. Results are discussed in light of hub and spoke networks and suggestions are made for future research.