À bord des aéronefs de transport commercial, lorsqu’un passager est victime d’un arrêt cardio-respiratoire, les membres d’équipage de cabine, appelés « PNC » (Personnel Navigant Commercial) dans la terminologie aéronautique, interviennent comme tout secouriste en initiant la chaîne de survie afin d’améliorer le pronostic vital de ce dernier. Dotés d’une formation très sérieuse et périodiquement mise à niveau, les PNC sont capables de prendre en charge des situations d’urgence médicales et de donner les premiers secours liés aux urgences potentielles, aux états de malaise, ainsi que ceux liés aux circonstances et à un environnement particulier. La réanimation cardio-pulmonaire, tâche exceptionnelle et rare en vol, génère le plus fréquemment des émotions négatives ainsi que du stress auprès des PNC. Cette recherche aborde le stress des membres d’équipage de cabine dans la prise en charge d’une réanimation cardio-pulmonaire en vol selon une approche psychologique et plus singulièrement celle en relation avec la théorie transactionnelle de Lazarus et Folkman (1984) dont l’évaluation cognitive et les « copings » des individus occupent une place centrale. Élaborée à partir d’un recueil de données construit par entretiens semi-directifs auprès d’un groupe de 32 PNC volontaires exerçant leur profession sur des aéronefs de petite capacité de transport passagers, elle se propose d’identifier les facteurs influençant le stress des PNC selon une perspective synchronique. Aussi, afin de cerner le plus d’explication possible de la variance du stress, nous avons pris en compte deux variables personnelles, l’expérience professionnelle et le lieu de contrôle des sujets. Les résultats indiquent que plusieurs facteurs peuvent prédire ou influencer l’état de stress des PNC. Ils montrent une relation significative entre le lieu de contrôle des sujets, l’évaluation cognitive de la situation aversive, le lieu de prise en charge de la victime en arrêt cardiaque et l’état de stress des PNC. Ainsi, les sujets « internalistes » évaluant la situation aversive comme un défi et développant des stratégies d’ajustement centrées sur les problèmes sont les moins stressés. Par ailleurs, le milieu aéronautique augmente l’état de stress des PNC en raison de la forte responsabilité morale envers la victime-passager, du confinement de la cabine, du délai de la mise en œuvre du quatrième maillon de la chaîne de survie ainsi que de la ressource sociale limitée en vol. Enfin, l’amélioration de la formation en premiers secours peut aider les PNC à mieux appréhender cette situation d’urgence en vol. / On board commercial transport aircraft when a passenger suffers from a cardiac arrest, the cabin crew members, called "PNC" (Personnel Navigant Commercial) in aviation terminology, act as any rescuer by initiating survival chain to improve the prognosis of the victim. With a very serious training and periodically upgrade, cabin crew members are able to handle medical emergencies and first-aid related to potential emergencies, discomfort states as well as those related to a circumstance and a particular environment. Cardiopulmonary resuscitation, exceptional and rare task in flight, generates the most frequent negative emotions and stress from cabin crew members. This research deals with the stress of cabin crew members in the management of a cardiopulmonary resuscitation in flight using a psychological approach and particularly the related transactional theory of Lazarus and Folkman (1984) in which appraisal and coping are central. Developed from a data collection built by semi-structured interviews with a group of 32 cabin crew members volunteers flying on small passenger carrying capacity aircraft, it aims to identify the factors influencing their stress in a synchronic perspective. Also, in order to identify the most possible explanation for the variance of stress, we took into account both personal variables such as professional experience and locus of control of the subjects.The results indicate that several factors can predict or influence the cabin crew members’stress. They show a significant relationship between the subject’s locus of control, appraisal of aversive situation, place of management of the victim in cardiac arrest and the stress of the cabin crew members. Thus, « internalist » subjects who assess the situation as a challenge and develop strategies focused on the problems are less stressed. Furthermore, the aviation industry increases the stress state of the cabin crew because of the strong moral responsibility to the victim-passenger, confinement of the cabin, the period of the implementation of the fourth link in the chain of survival (medicalized CPR) and the limited social resource in flight. At last, the improvement of first-aid training can help cabin crew members to manage better this specific situation on board.

The crew scheduling problem with attendance rates is highly relevant for regional passenger rail transport in Germany. Its major characteristic is that only a certain percentage of trains have to be covered by crew members or conductors, causing a significant increase in complexity. Despite being commonly found in regional transport networks, discussions regarding this issue remain relatively rare in the literature. We propose a novel hybrid column generation approach for a real-world problem in railway passenger transport. To the best of our knowledge, several realistic requirements that are necessary for successful application of generated schedules in practice have been integrated for the first time in this study. A mixed integer programming model is used to solve the master problem, whereas a genetic algorithm is applied for the pricing problem. Several improvement strategies are applied to accelerate the solution process; these strategies are analyzed in detail and are exemplified. The effectiveness of the proposed algorithm is proven by a comprehensive computational study using real-world instances, which are made publicly available. Further we provide real optimality gaps on average less than 10 % based on lower bounds generated by solving an arc flow formulation. The developed approach is successfully used in practice by DB Regio AG.

The air transportation market has been growing steadily for the past three decades since the airline deregulation in 1978. With competition also becoming more intense, airline companies have been trying to enhance their market shares and profit margins by composing favorable flight schedules and by efficiently allocating their resources of aircraft and crews so as to reduce operational costs. In practice, this is achieved based on demand forecasts and resource availabilities through a structured airline scheduling process that is comprised of four decision stages: schedule planning, fleet assignment, aircraft routing, and crew scheduling. The outputs of this process are flight schedules along with associated assignments of aircraft and crews that maximize the total expected profit. Traditionally, airlines deal with these four operational scheduling stages in a sequential manner. However, there exist obvious interdependencies among these stages so that restrictive solutions from preceding stages are likely to limit the scope of decisions for succeeding stages, thus leading to suboptimal results and even infeasibilities. To overcome this drawback, we first study the aircraft routing problem, and develop some novel modeling foundations based on which we construct and analyze an integrated model that incorporates fleet assignment, aircraft routing, and crew pairing within a single framework. Given a set of flights to be covered by a specific fleet type, the aircraft routing problem (ARP) determines a flight sequence for each individual aircraft in this fleet, while incorporating specific considerations of minimum turn-time and maintenance checks, as well as restrictions on the total accumulated flying time, the total number of takeoffs, and the total number of days between two consecutive maintenance operations. This stage is significant to airline companies as it directly assigns routes and maintenance breaks for each aircraft in service. Most approaches for solving this problem adopt set partitioning formulations that include exponentially many variables, thus requiring the design of specialized column generation or branch-and-price algorithms. In this dissertation, however, we present a novel compact polynomially sized representation for the ARP, which is then linearized and lifted using the Reformulation-Linearization Technique (RLT). The resulting formulation remains polynomial in size, and we show that it can be solved very efficiently by commercial software without complicated algorithmic implementations. Our numerical experiments using real data obtained from United Airlines demonstrate significant savings in computational effort; for example, for a daily network involving 344 flights, our approach required only about 10 CPU seconds for deriving an optimal solution. We next extend Model ARP to incorporate its preceding and succeeding decision stages, i.e., fleet assignment and crew pairing, within an integrated framework. We formulate a suitable representation for the integrated fleeting, routing, and crew pairing problem (FRC), which accommodates a set of fleet types in a compact manner similar to that used for constructing the aforementioned aircraft routing model, and we generate eligible crew pairings on-the-fly within a set partitioning framework. Furthermore, to better represent industrial practice, we incorporate itinerary-based passenger demands for different fare-classes. The large size of the resulting model obviates a direct solution using off-the-shelf software; hence, we design a solution approach based on Benders decomposition and column generation using several acceleration techniques along with a branch-and-price heuristic for effectively deriving a solution to this model. In order to demonstrate the efficacy of the proposed model and solution approach and to provide insights for the airline industry, we generated several test instances using historical data obtained from United Airlines. Computational results reveal that the massively-sized integrated model can be effectively solved in reasonable times ranging from several minutes to about ten hours, depending on the size and structure of the instance. Moreover, our benchmark results demonstrate an average of 2.73% improvement in total profit (which translates to about 43 million dollars per year) over a partially integrated approach that combines the fleeting and routing decisions, but solves the crew pairing problem sequentially. This improvement is observed to accrue due to the fact that the fully integrated model effectively explores alternative fleet assignment decisions that better utilize available resources and yield significantly lower crew costs. / Ph. D.

Contrairement aux autres biens meubles, les navires, les aéronefs et les objets spatiaux affectés à la navigation internationale sont rattachés à un Etat. Le lien de droit public établi entre ces engins et l’Etat est communément appelé « nationalité ». Mais ce terme n’exprime pas à leur propos une institution à tous égards identique à la nationalité des personnes. Le rattachement examiné ne repose en effet pas sur des éléments de fait (naissance, ascendance etc.), mais uniquement sur un acte administratif interne, l’immatriculation. L’étude de la pratique, notamment des conventions internationales et des législations nationales, montre clairement que – contrairement à ce qu’on soutient souvent – il n’y a pas lieu de subordonner ce rattachement à un lien effectif. Ce qui importe, compte tenu notamment du fait que ces engins évoluent dans des espaces soustraits à toute compétence territoriale, est d’identifier l’Etat qui est seul compétent à l’égard de l’« ensemble organisé » formé par le véhicule, les personnes et la cargaison à bord, et qui est responsable de ses activités. Le droit international interdit dès lors la double immatriculation, mais il laisse aux Etats le pouvoir discrétionnaire de déterminer les conditions d’attribution de leur « nationalité », sans subordonner l’opposabilité internationale de celle-ci à quelque autre exigence que ce soit. Le danger est toutefois que cela favorise un certain laxisme de l’Etat d’immatriculation, ce qui exposerait au risque que des dommages graves soient causés aux personnes impliquées dans les activités de ces engins et – surtout – aux tiers. Mais ce sont les obligations internationales imposées et les droits corrélatifs reconnus dans le chef de l’Etat d’immatriculation qui sont déterminants à cet égard et non quelque mystérieuse « effectivité » du rattachement. Autrement dit, s’il n’est pas nécessaire d’imposer à l’Etat d’immatriculation des conditions internationales limitant sa liberté dans l’attribution de sa « nationalité » aux engins, il est indispensable d’exiger que celui-ci respecte ses obligations, c’est-à-dire exerce effectivement son contrôle et sa juridiction. Cette constatation se vérifie quel que soit l’engin en cause. Le rattachement créé par l’immatriculation constitue donc une institution "sui generis", commune aux navires, aéronefs et objets spatiaux et dont le régime juridique est encadré par le droit international. / Unlike any other movable property, ships, aircraft and space objects that are engaged in international navigation are linked to a State. The legal connection established between these craft/vessels and the State is commonly referred to as “nationality”. However, in this case the term does not represent an institution identical in all respects to the nationality of persons. With regard to vessels, the legal connection to a State is not based on factual elements (such as birth, descent etc.), but merely on the internal administrative act of registration. The study of State practice, notably international conventions and national laws, clearly shows that – contrary to what is often argued – there is no need to make this connection dependent on a pre-existing effective link. What matters most, given that these craft navigate in international space beyond the territorial jurisdiction of sovereign States, is to identify the State that holds sole jurisdiction over said “organized entity” consisting of the vehicle, the persons and the cargo on board and that is responsible for its activities. Public international law therefore prohibits dual registration, but leaves States free to determine the conditions under which they will confer their “nationality”, without imposing any other requirement for the opposability of this legal bond to third States. The danger is that this situation encourages laxity on the part of the States of registry and therefore creates the potential for serious damage incurred by persons involved in these vessels’ activities and – mostly – by third persons. In this regard, it is the international obligations and corresponding rights of the States of registry which are critical, and not a mysterious “effectiveness” of the legal bond. In other words, it is not necessary to impose on the State of registry any international conditions which would limit its freedom with regard to the conferral of its “nationality” upon vessels. It is however indispensable to require that said State complies with its obligations, meaning that it has to effectively exercise its jurisdiction and control over those craft. This statement holds true regardless of the craft concerned. The legal bond created by the registration therefore constitutes a "sui generis" institution, common to ships, aircraft and space objects, and whose legal regime is governed by international law.