Air transportation offers both passenger and freight services that are essential for economic growth and development. In a highly competitive environment, airline companies have to control their operating costs by managing their flights, aircraft, and crews effectively. This motivates the extensive use of analytical techniques to solve complex problems related to airline operations planning, which includes schedule design, fleet assignment, aircraft routing, and crew scheduling. The initial problem addressed by airlines is that of schedule design, whereby a set of flights having specific origin and destination cities as well as departure and arrival times is determined. Then, a fleet assignment problem is solved to assign an aircraft type to each flight so as to maximize anticipated profits. This enables a decomposition of subsequent problems according to the different aircraft types belonging to a common family, for each of which an aircraft routing problem and a crew scheduling or pairing problem are solved. Here, in the aircraft routing problem, a flight sequence or route is built for each individual aircraft so as to cover each flight exactly once at a minimum cost while satisfying maintenance requirements. Finally, in the crew scheduling or pairing optimization problem, a minimum cost set of crew rotations or pairings is constructed such that every flight is assigned a qualified crew and that work rules and collective agreements are satisfied. In practice, most airline companies solve these problems in a sequential manner to plan their operations, although recently, an increasing effort is being made to develop novel approaches for integrating some of the airline operations planning problems while retaining tractability. This dissertation formulates and analyzes three different models, each of which examines a composition of certain pertinent airline operational planning problems. A comprehensive fourth model is also proposed, but is relegated for future research. In the first model, we integrate fleet assignment and schedule design by simultaneously considering optional flight legs to select along with the assignment of aircraft types to all scheduled legs. In addition, we consider itinerary-based demands pertaining to multiple fare-classes. A polyhedral analysis of the proposed mixed-integer programming model is used to derive several classes of valid inequalities for tightening its representation. Solution approaches are developed by applying Benders decomposition method to the resulting lifted model, and computational experiments are conducted using real data obtained from a major U.S. airline (United Airlines) to demonstrate the efficacy of the proposed procedures as well as the benefits of integration. A comparison of the experimental results obtained for the basic integrated model and for its different enhanced representations reveals that the best modeling strategy among those tested is the one that utilizes a variety of five types of valid inequalities for moderately sized problems, and further implements a Benders decomposition approach for relatively larger problems. In addition, when a heuristic sequential fixing step is incorporated within the algorithm for even larger sized problems, the computational results demonstrate a less than 2% deterioration in solution quality, while reducing the effort by about 21%. We also performed an experiment to assess the impact of integration by comparing the proposed integrated model with a sequential implementation in which the schedule design is implemented separately before the fleet assignment stage based on two alternative profit maximizing submodels. The results obtained demonstrate a clear advantage of utilizing the integrated model, yielding an 11.4% and 5.5% increase in profits in comparison with using the latter two sequential models, which translates to an increase in annual profits by about $28.3 million and $13.7 million, respectively. The second proposed model augments the first model with additional features such as flexible flight times (i.e., departure time-windows), schedule balance, and demand recapture considerations. Optional flight legs are incorporated to facilitate the construction of a profitable schedule by optimally selecting among such alternatives in concert with assigning the available aircraft fleet to all the scheduled legs. Moreover, network effects and realistic demand patterns are effectively represented by examining itinerary-based demands as well as multiple fare-classes. Allowing flexibility on the departure times of scheduled flight legs within the framework of an integrated model increases connection opportunities for passengers, hence yielding robust schedules while saving fleet assignment costs. A provision is also made for airlines to capture an adequate market share by balancing flight schedules throughout the day. Furthermore, demand recapture considerations are modeled to more realistically represent revenue realizations. For this proposed mixed-integer programming model, which integrates the schedule design and fleet assignment processes while considering flexible flight times, schedule balance, and recapture issues, along with optional legs, itinerary-based demands, and multiple fare-classes, we perform a polyhedral analysis and utilize the Reformulation-Linearization Technique in concert with suitable separation routines to generate valid inequalities for tightening the model representation. Effective solution approaches are designed by applying Benders decomposition method to the resulting tightened model, and computational results are presented to demonstrate the efficacy of the proposed procedures. Using real data obtained from United Airlines, when flight times were permitted to shift by up to 10 minutes, the estimated increase in profits was about $14.9M/year over the baseline case where only original flight legs were used. Also, the computational results indicated a 1.52% and 0.49% increase in profits, respectively, over the baseline case, while considering two levels of schedule balance restrictions, which can evidently also enhance market shares. In addition, we measured the effect of recaptured demand with respect to the parameter that penalizes switches in itineraries. Using values of the parameter that reflect 1, 50, 100, or 200 dollars per switched passenger, this yielded increases in recaptured demand that induced additional profits of 2.10%, 2.09%, 2.02%, and 1.92%, respectively, over the baseline case. Overall, the results obtained from the two schedule balance variants of the proposed integrated model that accommodate all the features of flight retiming, schedule balance, and demand recapture simultaneously, demonstrated a clear advantage by way of $35.1 and $31.8 million increases in annual profits, respectively, over the baseline case in which none of these additional features is considered. In the third model, we integrate the schedule design, fleet assignment, and aircraft maintenance routing decisions, while considering optional legs, itinerary-based demands, flexible flight retimings, recapture, and multiple fare-classes. Instead of utilizing the traditional time-space network (TSN), we formulate this model based on a flight network (FN) that provides greater flexibility in accommodating integrated operational considerations. In order to consider through-flights (i.e., a sequence of flight legs served by the same aircraft), we append a set of constraints that matches aircraft assignments on certain inbound legs into a station with that on appropriate outbound legs at the same station. Through-flights can generate greater revenue because passengers are willing to pay a premium for not having to change aircraft on connecting flights, thereby reducing the possibility of delays and missed baggage. In order to tighten the model representation and reduce its complexity, we apply the Reformulation-Linearization Technique (RLT) and also generate other classes of valid inequalities. In addition, since the model possesses many equivalent feasible solutions that can be obtained by simply reindexing the aircraft of the same type that depart from the same station, we introduce a set of suitable hierarchical symmetry-breaking constraints to enhance the model solvability by distinguishing among aircraft of the same type. For the resulting large-scale augmented model formulation, we design a Benders decomposition-based solution methodology and present extensive computational results to demonstrate the efficacy of the proposed approach. We explored four different algorithmic variants, among which the best performing procedure (Algorithm A1) adopted two sequential levels of Benders partitioning method. We then applied Algorithm A1 to perform several experiments to study the effects of different modeling features and algorithmic strategies. A summary of the results obtained is as follows. First, the case that accommodated both mandatory and optional through-flight leg pairs in the model based on their relative effects on demands and enhanced revenues achieved the most profitable strategy, with an estimated increase in expected annual profits of $2.4 million over the baseline case. Second, utilizing symmetry-breaking constraints in concert with compatible objective perturbation terms greatly enhanced problem solvability and thus promoted the detection of improved solutions, resulting in a $5.8 million increase in estimated annual profits over the baseline case. Third, in the experiment that considers recapture of spilled demand from primary itineraries to other compatible itineraries, the different penalty parameter values (100, 50, and 1 dollars per re-routed passenger) induced average respective proportions of 3.2%, 3.4%, and 3.7% in recaptured demand, resulting in additional estimated annual profits of $3.7 million, $3.8 million, and $4.0 million over the baseline case. Finally, incorporating the proposed valid inequalities within the model to tighten its representation helped reduce the computational effort by 11% on average, while achieving better solutions that yielded on average an increase in estimated annual profits of $1.4 million. In closing, we propose a fourth more comprehensive model in which the crew scheduling problem is additionally integrated with fleet assignment and aircraft routing. This integration is important for airlines because crew costs are the second largest component of airline operating expenses (after fuel costs), and the assignment and routing of aircraft plus the assignment of crews are two closely interacting components of the planning process. Since crews are qualified to typically serve a single aircraft family that is comprised of aircraft types having a common cockpit configuration and crew rating, the aircraft fleeting and routing decisions significantly impact the ensuing assignment of cockpit crews to flights. Therefore it is worthwhile to investigate new models and solution approaches for the integrated fleeting, aircraft routing, and crew scheduling problem, where all of these important inter-dependent processes are handled simultaneously, and where the model can directly accommodate various work rules such as imposing a specified minimum and maximum number of flying hours for crews on any given pairing, and a minimum number of departures at a given crew base for each fleet group. However, given that the crew scheduling problem itself is highly complex because of the restrictive work rules that must be heeded while constructing viable duties and pairings, the formulated integrated model would require further manipulation and enhancements along with the design of sophisticated algorithms to render it solvable. We therefore recommend this study for future research, and we hope that the modeling, analysis, and algorithmic development and implementation work performed in this dissertation will lend methodological insights into achieving further advances along these lines. / Ph. D.

Doctor of Philosophy / Department of Economics / Philip G. Gayle / My research focuses primarily on industrial organization and applied microeconomics. Specifically, I have extensively studied the airline industry. My first essay considers the effect of the Delta/Continental/Northwest codeshare alliance. Codeshare agreements can benefit airlines due to network expansion and benefit consumers by eliminating a double markup on flight itineraries with multiple operating carriers. However, policymakers have expressed concern that an alliance between airlines may facilitate price and service collusion in markets where codeshare partners’ services overlap. I develop a structural econometric model that is able to separately identify supply and demand factors as sources of price-quantity changes caused by the creation of the alliance. The estimates from the model show both collusive and demand increasing effects associated with the codeshare alliance. However, the demand increasing effect is larger than the collusive effect. My second essay considers the effects of the recent Delta/Northwest merger. This merger is of particular interest because the two airlines are codeshare partners. Using pre-merger data, a counterfactual simulation is performed in which Delta and Northwest are assumed to merge. The results indicate that codeshare products owned by the merging firms experience higher predicted price increases relative to pure online products. In addition, the mean predicted price increases are relatively small across most markets. I also examine pre-merger predictions with post-merger data and analysis and find that the pre-merger predictions roughly accord with “de-merger” simulated effects using post-merger data. My third essay takes an extended look at airline mergers. When the Delta/Northwest merger was approved by the Department of Justice, consumer groups and policymakers were concerned that the merger and poor economic outlook would act as a catalyst for more mergers. This paper examines this possible scenario using simulations to model the effects of other codeshare partners merging in addition to Delta and Northwest. Results indicate that the predicted price increases for all mergers exhibit relatively small averages but large variances across markets. Further, the largest predicted price increases affect a small percent of products and an even smaller percent of passengers who choose products owned by a merging firm.

According to a recent report by the U.S. Senate Joint Economic Committee, the costs of domestic air traffic delays were estimated to be a staggering $41 billion in 2007. Of this, $19.1 billion was attributed to airline operating costs and $12 billion was attributed to passenger delays. In instances of irregular operations, an airline's primary objective is to get operations back to normal as quickly as possible while incurring minimal cost. Historically, airlines have prioritized recovering schedules for aircraft and crew before attempting to reaccommodate disrupted passengers. The literature has not examined how proactive movement of passengers can be used to mitigate the impact of irregular operations. This work bridges this gap by exploring how early standby fees (which influence customer behavior) can be utilized to improve operations. This research uses a variety of public and private data sources to construct a micro-level simulation to explore the impact that early standby pricing policies have on aggregate and average delay for disrupted passengers. Three distinct modules developed for use in the simulation have broader applications to the research community: (1) logic for a passenger reaccommodation algorithm; (2) a model that predicts the number of early standby passengers; and (3) a model to predict the probability a passenger misses a connecting flight. Preliminary results confirm the hypothesis that early standby pricing policies affect both profitability and operational performance. A simple example illustrates that an airline faces an important tradeoff when setting an early standby pricing policy: the early standby fee that maximizes an airline's profitability is different from the early standby fee that yields the lowest aggregate and average delay metrics for customers. This dissertation proposes a new product that remedies these competing objectives by improving them both simultaneously.

The advancement of Information Technology (IT) has changed the business landscape in many industries and especially the airline sector. Modern Information Communication Technologies (ICT) provide powerful tools for organizations and can significantly influence their operation, structure, and strategy. The emergence of mobile technologies has created a new innovation for airline companies by increasing the availability, frequency, and speed of communication between the company and their customers. This research aims to investigate the factors influencing the customers behavioural intention to adopt and utilize mobile services during their travel process. Technology Acceptance Model (TAM) and Innovation Diffusion Theory (IDT) provide the theoretical basis for explaining how consumers perceive mobile services which they access and operate by their mobile handset. To achieve that, this research employed a mixed method of quantitative and qualitative approaches with a dominant quantitative method. A consumer web-based survey was conducted in the Saudi Arabia travel sector with respect to mobile services usage in airline sector , 307 valid questionnaires were received and analyzed by using SPSS (V.18), correlation, regression and factor analysis tests were conducted . The findings of this research revealed that, perceived usefulness, mobility and compatibility are loaded to be one predictor of behavioural intention to use mobile services in Saudi Arabia. The reason behind it may be interpreted as customers nowadays have seen mobility and compatibility as attributes of perceived usefulness. Further, social influence, perceived ease of use and personal innovativeness were found to significantly influence the behavioural intention .whereas, perceived risk was found not to be a predictor to the behavioural intention to use mobile services in Saudi Arabia. Finally, the model analysis and survey evaluation enable airline companies to make mobile commerce service provision decision, these findings contribute to a road map for airline companies to encourage their customers to adopt mobile services and keep them engaged during the overall travel life cycle.

This thesis is involved with exploration of key changes drivers and market phenomena in the Southeast Asia and the development of new conceptual frameworks for business environmental analysis of airlines. The research is constructed under the phenomenology paradigm which adopts a coherentism approach and mainly takes airline industry’s publications, statistics, and executives as units of analysis. Hermeneutic phenomenology, a single-embedded case study, concurrent triangulation mixed method, and grounded theory are all used as methodologies. Methods using document reviews, interviews, and questionnaires are applied to surface the key changes drivers, market phenomena and the perceptions of the importance of changes factors. The collected data are analysed by content analysis, thematic analysis, cognitive mapping analysis, constant comparative analysis and descriptive analysis to classify, generalise and develop into proper forms. The research reveals that ‘market’, ‘competition/strategy’, ‘regulation/policy’, ‘infrastructure/resource’, ‘cooperation’, ‘distribution’, ‘technology, and ‘broad’ factors are discovered as key change drivers. Their different importance levels are measured by occurrences, density, centrality, and tail occurrences as root causes of changes. The characteristics of their interrelationships are based on directional and influential dimensions. There are 16 emerged changes/market phenomena and 11 generalised conceptual frameworks and 3 newly developed frameworks for analysing the airline business environment. The quantitative findings from content analysis are evaluated by inter-coder analysis which achieves kappa coefficient = 0.87 indicating high reliability of the analysis. The qualitative findings are qualified through ten criteria assessment of research quality. The deliverables provide both theoretical and methodological contributions. The research limitations are found in some sources of collected data and findings which are caused by scarce data availability and three types of biases. The recommendations for future research into financial performance, changes’ leading indicators and comparative in-depth study in other ASEAN countries and regions are made.

<p>This dissertation extends the empirical industrial organization literature with two essays on strategic decisions of firms in imperfectly competitive markets and one essay on how inertia in consumer choice can result in significant welfare losses. Using data from the airline industry I study a well-known puzzle in the literature whereby incumbent firms decrease fares when Southwest Airlines emerges as a potential entrant, but is not (yet) competing directly. In the first essay I describe this so-called Southwest Effect and use reduced-form analysis to offer possible explanations for why firms may choose to forgo profits today rather than wait until Southwest operates the route. The analysis suggests that incumbent firms are attempting to signal to Southwest that entry is unprofitable so as to deter its entry. The second essay develops this theme by extending a classic model from the IO literature, limit pricing, to a dynamic setting. Calibrations indicate the price cuts observed in the data can be captured by a dynamic limit pricing model. The third essay looks at another concentrated industry, mobile telecoms, and studies how inertia in choice (be it inattention or switching costs) can lead to consumers being on poorly matched cellphone plans and how a simple policy proposal can have a considerable effect on welfare.</p> / Dissertation

This study examined consumer attitude towards adding branded quick-service items on domestic airline in-flight menus with the aim of assessing the variables of perceived customer value and customer satisfaction. A random sample of one hundred sixteen frequent flyers residing in the United States participated in the study. An examination of consumer attitude towards branded quick-service menu items if introduced on domestic in-flight menus was performed. Multiple regression analysis was used to determine which of the four relationships was the most significant. The results showed that frequent flyer satisfaction with branded quick-service food items had the most significant relationship with perceived satisfaction of adding branded quick-service foods to coach class in-flight meal service.

Doctor of Philosophy / Department of Economics / Philip G. Gayle / This dissertation constitutes two essays in the field of industrial organization. Specifically, the research focuses on empirically assessing the market effects of airline alliances. The first essay examines how codesharing, a form of strategic alliances, by airlines affects market entry decisions of potential competitors. Researchers have written extensively on the impact that strategic alliances between airlines have on airfare, but little is known of the market entry deterrent impact of strategic alliances. Using a structural econometric model, this essay examines the market entry deterrent impact of codesharing between incumbent carriers in U.S. domestic air travel markets. We find that a specific type of codesharing between market incumbents has a market entry deterrent effect to Southwest Airlines, but not other potential entrants. Furthermore, we quantify the extent to which market incumbents’ codesharing influences market entry cost of potential entrants. The second essay examines the effects of granting Antitrust Immunity (ATI) to a group of airlines. Airline alliance partners often want to extend cooperation to revenue sharing, which effectively implies joint pricing of their products (explicit price collusion). To explicitly collude on price, airlines must apply to the relevant government authorities for ATI (U.S. Department of Justice and Department of Transportation in the case of air travel markets that have a U.S. airport as an endpoint), which effectively means an exemption from prosecution under the relevant antitrust laws. Whether consumers, on net, benefit from a grant of ATI to partner airlines has caused much public debate. This essay specifically investigates the impact of granting ATI to oneworld alliance members on their price, markup, and various measures of cost. The evidence suggests that the grant of ATI facilitated a decrease in partner carriers’ marginal cost, and increased (decreased) their markup in markets where their service do (do not) overlap. Furthermore, member carriers’ price did not change (decreased) in markets where their services do (do not) overlap, implying that consumers, on net, benefit in terms of price changes.

Doctor of Philosophy / Department of Economics / Philip G. Gayle / This dissertation is composed of two essays in the field of Industrial Organization. Specifically, the empirical studies are conducted by focusing on the market structure and competition issues in the airline industry. The first essay investigates entry deterrence through incumbents’ pricing strategies in the airline industry. Recent research finds evidence that incumbent airlines tend to cut fares in response to the “threat” of entry by Southwest Airlines. Instead of focusing on the entry threat by a single carrier, this essay re-examines this issue by looking at incumbent airlines’ price response when entry is threatened by a wider variety of potential entrant airlines. Results show that incumbents’ response vary by the identity of the firm making the threat. As expected, incumbents cut fares in response to the threat of entry by some potential entrants; however, a new result is also found that incumbents may respond by raising their fare depending on who is making the threat. The second essay looks into an antitrust-relevant issue in the airline industry. Proper antitrust analysis often focuses on whether the concerned differentiated products are truly competing with each other. This essay uses a structural econometric model to investigate whether nonstop and connecting air travel products effectively compete with each other. Estimate results suggest that connecting products may be an attractive alternative to nonstop products for leisure travelers but less so for business travelers. If connecting products are counterfactually eliminated, the empirical model predicts small price changes for nonstop products. This suggests that the two product types only weakly compete with each other and can be treated as being in separate product markets for antitrust purposes.

This thesis describes the process of integration between airlines and its positive and negative impacts on customers. It deals with characteristic features of individual forms of integration with the greatest attention paid to alliances and mergers. With respect to the fact that the passenger's choice of airline is to a large extent influenced by the price of the ticket, an empirical model is introduced to explore the impact of the membership in one of the global alliances on the final price of the long-haul tickets. Besides, the attention is paid to the nature and diversification of services provided. In the next section the thesis deals with the upcoming merger between British Airways and Iberia, its preconditions, form of the new company and identification of the potential risk factors that could have a negative impact on the company.