Optimization Model for an Airline Crew Rostering Problem: Case of Garuda Indonesia

This paper discusses the cockpit crew rostering problem at Garuda Indonesia, taking into account a number of internal cockpit crew labor regulations. These internal labor regulations are in general more restrictive at Garuda Indonesia than at other airlines, so that modeling the cockpit crew rostering problem for Garuda Indonesia is challenging. We have derived mathematical expressions for the cockpit crew labor regulations and some technical matters. We model a non-linear integer programming for the rostering problem, using the average relative deviation of total flight time to the ideal flight time as the objective function. The optimization model have been tested for all classes of cockpit crews of Garuda Indonesia, using a simulated annealing method for solving the problem. We obtained satisfactory rosters for all crew members in a short amount of computing time. This shows that the optimization problem is well-defined

Hybrid methods for integrated aircraft routing and crew pairing problem with short flight legs

The aircraft routing and crew pairing problems are two processes that are difficult to be solved in the airline operations planning due to the rules that each flight leg needs to be operated on by one aircraft and one crew pair. These two problems, though interrelated in practice, are usually solved sequentially and often leads to suboptimal solution. Thus, this research contributes to the solution of the integrated aircraft routing and crew pairing problem in order to determine the minimum cost of this integrated problem where each flight leg is covered by one aircraft and one crew pair. This study also considers short connection between two flight legs in order to ensure that the crews do not change the aircraft if the connection time is in between 20 to 59 minutes. Another consideration is the restricted connection that imposes penalty costs when the second flight leg uses the same crew but not the same aircraft. Based on the literature review, most of the existing solutions concentrate on minimizing the planned costs. Although the minimum costs are significantly important in airline operations planning, the efficiency of a solution method in terms of computational time cannot be neglected. It is necessary to solve the integrated problem by using an efficient model that is able to generate a good high quality solution in a short time as requested by the airline industry. In order to solve the problem, a set of feasible aircraft routes and crew pairs are initially generated to be used as the input data in solving the integrated model effectively. There are two heuristic methods which are proposed in generating the set of feasible aircraft routes and crew pairs namely constructive-based heuristic and Genetic Algorithm (GA). The generated feasible aircraft routes and crew pairs are then used in solving the integrated problem by using Integer Linear Programming (ILP) method, Dantzig Wolfe Decomposition method, Benders Decomposition method and Particle Swarm. Computational results obtained from these methods are then compared by testing them on four types of aircraft with different number of flight legs based on Malaysia local flights for one week flight cycle. From the numerical results, it can be concluded that the proposed methods are more efficient compared to the ILP method available in the literature in terms of the computational time where the hybrid algorithm of GA and Benders Decomposition is found to be advantageous compared to the others. The maximum cost deviation of only 4.77% also justifies the strength of this hybrid algorithm. One possible future research that can be extended from this study would be the development of an algorithm that incorporates a parallel GA within the proposed methods for larger instances which are likely to exist in international flights in order to speed up the planning process

An investigation of the practices used in airline crew scheduling and their impact on the physical and mental health of airline crew

The literatures surrounding the topics of crew scheduling optimization and crew health are often researched separately. The models are disconnected from the people they affect and are often seen as separate and neutral entities, despite being intrinsically connected with the mental and physical health of flight crews, in the same way that a typical work schedule impacts the physical and mental health of traditional full-time employees. With this in mind, this report gives a high-level overview of popular scheduling models and also, more importantly examines how the use of these models and current schedule optimization practices directly and indirectly impact the health of flight crews.Informatio

Havacılık Sektöründe Ekip Planlama Yönetimi: Bir Türk Havayolu Örneği Crew Planning Management in Aviation Industry: A Turkish Airline Case

Havayolu taşımacılığının günümüzde ortadan kalkmış olan sınırlar ve müşteri ihtiyaçlarının anında karşılanma isteği gibi nedenler dolayısıyla gün geçtikçe artması havayolu işletmelerinin ihtiyaç duyduğu uçuş personeli sayısını da arttırmaktadır. Bu sebeple bu çalışmada havacılık sektöründe ekip planlama fonksiyonunun faaliyetleri incelenmiş, ekip planlama yönetiminde dikkate alınan matematiksel kısıtlar kadar insani kısıtların da önemine vurgu yapılmak istenmiştir. Bu doğrultuda Türkiye’de faaliyet gösteren bir havayolu şirketinde üst düzey yöneticiler ve ekip planlama çalışanlarıyla odak grup görüşmeleri yapılmıştır. Ekip planlamanın iki temel fonksiyonu olan ekip eşleme (pairing) ve ekip atama (rostering) faaliyetleri yerine getirilirken dikkate alınan ve uygulanan unsurlar çalışmanın sonucunda elde edilen bulgulardır. Ekip planlama uygulamalarının bilimsel literature uygunluğu da dikkate alınmıştır. Ayrıca bu bulgulardan yola çıkarak ekip planlama faaliyetleri için 5 temel unsur ortaya konmuş olup bu unsurlar; kurallara ve zindelik seviyesine uyum, insan kaynağını hoyratça kullanmama, çalışan memnuniyetini sağlama, birim ekip maliyetlerinin düşürülmesi ve hizmet düzeyinin yüksek tutulması olarak sıralanmaktadır. Use of air transport is increasing steadily, due to the fact that today’s boundaries have been lifted and customer needs are being met instantaneously, which allows growth in the aviation industry. In this study, the activities of crew planning were examined and it was aimed to emphasize the importance of human constraints as well as the mathematical constraints considered in crew planning management. In line with this, focus group interviews were conducted with senior managers and crew planning personnel who are working in an airline company operating in Turkey. When crew pairing and rostering activites are carried out, the factors taken into account and applied are the findings obtained as a result of the study. Academic literature conformity of crew planning applications is also taken into consideration. Finally, five basic dimensions for crew planning activities have been set out from these findings; compliance with rules and personnel wellness level, not using human resourses harshly, ensuring employee satisfaction, reducing unit crew costs and keeping service level high

An Integer Programming Approach to Generating Airline Crew Pairings

Key Words: integer programming; column generation; crew pairing; crew scheduling; airline planning. The ability to generate crew pairings quickly is essential to solving the airline crew scheduling problem. Although techniques for doing so are well-established, they are also highly customized and require significant implementation efforts. This greatly impedes researchers studying important problems such as robust planning, integrated planning, and automated recovery, all of which also require the generating of crew pairings. As an alternative, we present an integer programming (IP) approach to generating crew pairings, which can be solved via traditional methods such as branch-and-bound using off-the-shelf commercial solvers. This greatly facilitates the prototyping and testing of new research ideas. In addition, we suggest that our modeling approach, which uses both connection variables and marker variables to capture the non-linear cost function and constraints of the crew scheduling problem, can be applicable in other scheduling contexts as well. Computational results using data from a major U.S. hub-and-spoke carrier demonstrate the performance of our approach.

Airline Planning under Uncertainty.

In this dissertation, we study the impact of uncertainty associated with potential delays on the operational performance of the airline plans, considering different stages of the airline planning process. In the first part of this dissertation, we investigate the potential for flight delays to propagate throughout a passenger airline network. We also define metrics to quantify delay propagation by analyzing the connections in a flight network. As the computational results demonstrate, delays can sometimes propagate substantially and have a major impact on network efficiency. Therefore, in the second part, we develop a linear programming approach to strategically use slack in the network in order to mitigate the impact of disruption without increasing cost. In these models we allow flight departure times to change within a given time window while keeping the original connections feasible but re-allocating slack where it can best be utilized. The motivation for the third part of this dissertation stems from the fact that re-timing the schedule per se cannot fully capture all the opportunities for improved robustness. Instead, it may also be necessary to change the fleet assignment and crew schedule. Thus, in a robust planning tool, it is necessary to schedule flights across all fleet-types simultaneously. This, in turn, increases the number of flights to be considered which dramatically impacts tractability. Therefore, it is essential to generate crew pairings (sequences of flights that can be covered by a single crew) on larger flight networks. In the third part, we present a new, integer programmingbased approach to supplement the existing techniques for generating crew pairings. To demonstrate the performance of this approach, computational experiments based on data from a major U.S. carrier are presented.Ph.D.Industrial & Operations EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/60861/1/shervin_1.pd

Optimisation intégrée des rotations et des blocs mensuels personnalisés des équipages en transport aérien

Le problème de la construction des horaires d’équipage pour les compagnies aériennes consiste à assigner un groupe d’équipage à un ensemble planifié de segments de vols. Ce problème doit également respecter des règles de travail définies par la convention collective et les autorités du transport aérien. Le problème de la construction des horaires d’équipage a reçu une attention particulière en recherche opérationnelle car après le carburant, le coût des équipages constitue la plus grande dépense des compagnies aériennes. En raison de la grande taille du problème et de la complexité des règles de travail, ce problème est traditionnellement traité en deux étapes qui sont résolues séquentiellement : la construction de rotations et la construction de blocs mensuels. La première construit un ensemble de rotations réalisables à coût minimum afin que chaque vol prévu puisse être réalisé par un équipage. Les rotations réalisables sont celles juxtaposant des vols conformément aux règles de la convention collective entres les employés et la compagnie aérienne. La deuxième étape construit des blocs mensuels pour les membres d’équipage en combinant les rotations trouvées précédemment avec les repos, et d’autres activités. Chaque bloc mensuel doit satisfaire certaines règles définies par le contrat de travail. Les membres de l’équipage sont divisés en deux groupes selon leurs rôles et leurs responsabilités : les personnels du poste de pilotage et les personnels de la cabine des passagers. Les pilotes, les copilotes et les mécaniciens de bord font partie du personnel du poste de pilotage. Le personnel du poste de pilotage est qualifié pour piloter un avion ou une famille d’avions. Le capitaine de cabine et les agents de bord font partie des membres de la cabine des passagers. Par le passé, les chercheurs se sont concentrés sur la réduction des coûts associés au personnel du poste de pilotage car leurs salaires sont plus élevés que ceux des membres de la cabine des passagers. Dans cette thèse, nous nous concentrons uniquement sur le personnel du poste de pilotage. La construction des blocs mensuels varie pour chaque compagnie aérienne. Toutefois, on peut classer les méthodes en deux catégories : la construction des blocs anonymes (bidline) et la construction des blocs personnalisés. Pour les blocs anonymes, les horaires sont construits de manière à couvrir toutes les rotations sans connaître les préférences des employés. Les blocs sont ensuite présentés aux membres d’équipage qui sélectionnent les blocs qu’ils veulent faire. Contrairement aux blocs anonymes, les blocs personnalisés tiennent compte des préférences des membres de l’équipage. La construction de ces blocs se fait selon deux objectifs : le rostering et les blocs personnalisés avec séniorité (preferrential bidding). Le premier maximise la satisfaction globale des membres d’équipage sans considérer la séniorité. Le second priorise la satisfaction des membres ayant le plus d’ancienneté. D’un point de vue historique, la construction des blocs anonymes a été l’approche la plus utilisée par les compagnies aériennes nord-américaines alors que la construction des blocs personnalisés a été plus fréquente en Europe. Cependant, les blocs personnalisés sont aujourd’hui une approche de planification utilisée par de plus de compagnies aériennes nord-américaines car ils sont plus avantageux à la fois pour les membres de l’équipage et les compagnies aériennes. Par le passé, le problème de construction des rotations et le problème de construction des blocs mensuels ont été modélisés indépendamment. Bien que cette approche réduise la complexité du problème, elle ne considère pas les contraintes de construction de blocs mensuels lors de la construction des rotations. Ce faisant, il n’est pas possible de garantir une solution optimale pour tous les membres de l’équipage. Plus récemment, des chercheurs ont commencé à intégrer ces problèmes. Le problème de construction intégrée de rotations et de blocs mensuels anonymes pour les pilotes a été étudié par Saddoune et al. Cependant, au meilleur de nos connaissances, il n’existe pas de littérature sur le problème d’intégration de construction des rotations et des blocs mensuels personnalisés. Le premier objectif de cette thèse est de présenter une revue de la littérature sur le problème de construction des horaires d’équipage en transport aérien. De plus, nous présentons un modèle mathématique et une approche de résolution pour le problème séquentiel de construction des blocs mensuels personnalisés. Au meilleur de notre connaissance, aucun modèle permettant de prendre en compte les préférences des pilotes n’a été introduit dans la littérature. Nous avons également observé que peu de chercheurs comparent leurs méthodes sur les mêmes données. Nous proposons donc un ensemble d’instances ainsi qu’un générateur de préférences qui est disponible en ligne pour des fins de comparaison. Dans le deuxième objectif de cette thèse, nous considérons le problème intégré de construction des rotations et des blocs mensuels personnalisés. Nous proposons un algorithme heuristique qui construit simultanément des horaires mensuels pour les pilotes et copilotes, tout en respectant les préférences personnelles et les contraintes de sécurité. L’algorithme proposé alterne entre les problèmes de construction des horaires des pilotes et des copilotes afin d’obtenir des rotations similaires, même lorsque les blocs mensuels sont différents. De plus, en raison des perturbations qui arrivent souvent durant l’opération, nous nous sommes intéressés à développer un algorithme permettant d’obtenir une solution robuste ; c’est-à-dire que nous minimisons la propagation de la perturbation d’un premier vol aux autres vols et aux autres membres d’équipage. La troisième contribution de cette thèse vise à satisfaire cet aspect. Pour ce faire, nous résolvons le problème de mise à jour des blocs mensuels simultanément pour les pilotes et les copilotes. Nous visons à maintenir les services de vols et les rotations en commun pour les pilotes et les copilotes dans les solutions de mise à jour. Nous proposons ainsi un algorithme heuristique qui alterne entre le problème de mise à jour des horaires mensuels des pilotes et des copilotes. Pour résumer, cette thèse étudie le problème de construction intégrée des blocs mensuels personnalisés pour les membres de l’équipage. Nous nous concentrons à la fois sur la planification et sur la mise à jour des blocs mensuels.----------ABSTRACT : The airline crew scheduling problem assigns a group of crew members to a set of scheduled flights. This scheduling problem should respect also a set of safety regulations and collective conventions. The airline crew scheduling has received special attention in Operations Research because after fuel, the cost of crew members is the second largest cost for airlines. Due to complexity, traditionally researchers divided this problem into two steps which are solved sequentially: crew pairing and crew assignment. The former constructs a set of minimum cost anonymous feasible pairings for covering the scheduled flights while pairing régulations are taken into account. The latter combines the anonymous pairings with vacations, preassigned activities, and rest periods over a planning horizon (usually a month) to form new schedules for crew members while satisfying safety regulations. Crew members are divided into two groups based on their roles and responsibilities: the cockpit crew members and the cabin crew members. Cockpit crew members are composed of the pilot (captain), copilot (first officer), and flight engineer (for large fleets). The cockpit crew members are qualified to fly one or a family of aircraft types. The cabin crew members are the cabin captain and the flight attendants. Because cockpit crew members are paid substantially higher than cabin crew members, most of the literature has focused on cockpit crew members. In this thesis, we also focus on cockpit crew members composed of pilots and copilots. Despite crew pairings problem which always aims at constructing anonymous pairings, there are two general approaches that airlines consider when solving the crew assignment problem: constructing bidline schedules or personalized schedules. Bidline schedules are anonymous schedules for which the crew preferences and needs are not taken into account. After constructing bidline schedules for crew members, the airlines announce them to the crew members and crew members select the bidlines according to seniority order. In contrast to bidline schedules, personalized schedules consider crew member’s preferences and needs for constructing and allocating the schedules. There are two general ways for constructing personalized schedules: rostering and seniority-based. The former favors providing a maximum global satisfaction for crew members and does not take crew members seniority into account. The latter prioritizes satisfaction of more senior crew members to the junior ones. From a historical point of view, bidline scheduling has been the most common approach at North American airlines whereas personalized scheduling has been more common in Europe. However, personalized schedules are now becoming a common scheduling approach at american airlines by offering advantages for both crew members and airlines. Each of the crew pairing problem and crew assignment problem were modeled independently. This traditional sequential approach reduces the complexity of crew scheduling problem but does not guarantee a global optimum solution for crew members because the constraints of monthly schedules are not taken into account when the pairings are being constructed. More recently, researchers have started to study the integration of the crew pairing and crew assignment problems. The problem of integrated bidline scheduling for pilots has been studied by Saddoune et al. However, integrated personalized crew scheduling for pilots and copilots simultaneously has not been the subject of study so far. The first objective of this thesis is to present an extensive review of literature about airline crew scheduling problem. In addition, in the context of sequential scheduling approach, we present a mathematical model and solution approach for personalized pilot assignment problem. To the best of our knowledge, this personalized assignment model that takes into account the pilots preferences has not yet been introduced in the literature. Furthermore, we observed that researchers frequently do not compare their methods on the same data due to the lack of access to common data sets. Therefore, we made all the data sets and crew preference generators available online which will allow other researchers to do so. As the second objective in this thesis, we consider the integrated personalized crew scheduling problem that simultaneously constructs monthly schedules for pilots and copilots while respecting the personal preferences and safety constraints. In addition, we are interested to maintain the robustness of the crew schedules due to the real-life perturbations that arrive while the planned schedules are being operated. At the operational level, the pilots and copilots must have similar pairings when possible to prevent the propagation of delays throughout the schedules. We present a heuristic algorithm that alternates between the pilot and copilot scheduling problems in order to obtain similar pairings even when the monthly schedules are different. In real life, various disruption sources such as weather conditions may result in delaying or canceling the scheduled flights. These delayed or canceled flights will affect the crew schedules. Due to delay propagation, robust crew recovery problem is very significant. As the third contribution of this thesis, we solve the recovery problem simultaneously for pilots and copilots where the planned schedules are constructed using personalized scheduling approach. We aim at keeping the duties and pairings in common during the recovery solution process. This aim is satisfied by considering heuristic algorithm that alternates between pilots and copilots recovery problems. The re-scheduled flights are considered to be given as an input data.To summarize, this thesis studies integrated personalized crew scheduling problem, in both planning and operational level, which simultaneously constructs/recovers monthly schedules for both pilots and copilots