This thesis is focused on two topics. The first topic is the General Aviation (GA) demand forecasting models. The contributions to this topic are three fold: 1) we calibrated an econometric model to investigate the impact of fuel price on the utilization rate of GA piston engine aircraft, 2) we adopted a logistic model to identify the relationship between fuel price and an aircraft's probability of staying active, and 3) we developed an econometric model to forecast the airport-level itinerant and local GA operations. Our calibration results are compared with those reported in literature. Demand forecasts are made with these models and compared with those prepared by the Federal Aviation Administration. The second topic is to model the air traffic in the Organized Track System (OTS) over the North Atlantic. We developed a discrete-time event model to simulate the air traffic that uses the OTS. We proposed four new operational procedures to improve the flight operations for the OTS. Two procedures aim to improve the OTS assignments in the OTS entry area, and the other two aim to benefit flights once they are inside the OTS. The four procedures are implemented with the simulation model and their benefits are analyzed. Several implementation issues are discussed and recommendations are given. / Ph. D.

This thesis presents a performance assessment of flight operations in the North Atlantic Organized Track System (OTS) using the Global Oceanic Model. The main contributions of the study are: a) improvements to the logic of the Global Oceanic Model; b) prediction of benefits among various aircraft separation minima and operational policies to assign flights to tracks in the OTS system; and c) forecast of OTS traffic over North Atlantic from 2020 to 2040. The preliminary results show that a concept of operation with longitudinal separation minima of 15 nm and information of the flight cost matrix provides average fuel savings of 93 kilograms per flight using 2020 traffic. The fuel savings increase to 170 kilograms per flight using traffic levels expected in the year 2040. A new operational track assignment routine is developed and it could save around 40 kilograms per flight compared with the current concept of operations. The study results show a shortage of capacity of the Organized Track System in the future. The analysis shows that the OTS configuration used today and in 2020 is unable to accommodate the traffic projected in 2040. The analysis concludes that more tracks will be needed to maintain an acceptable level of service. / MS / The North Atlantic Organized Track System (OTS) are directional tracks for aircraft to fly between North America and Europe. This thesis presents a performance assessment of flight operations in the North Atlantic using a computer simulation model -- Global Oceanic Model. The main contributions of the study are: a) improvements to the logic of the Global Oceanic Model; b) prediction of benefits among various aircraft separation minima and operational policies to assign flights to tracks in the OTS system; and c) forecast of OTS traffic over Atlantic from 2020 to 2040. The preliminary results show that the predicted average fuel savings in the year 2020 are 93 kilograms per flight when aircraft are separated 15 nm longitudinally and assigned to tracks based on the flight cost matrix. The average fuel savings increase to 170 kilograms per flight using traffic levels expected in the year 2040. Additionally, a new operational track assignment routine is developed and it could save around 40 kilograms per flight compared with the current concept of operations. In conclusion, the Organized Track System configuration used today may be unable to accommodate the traffic projected in the year 2040. The shortage of capacity of the OTS indicates that more tracks will be needed to maintain an acceptable level of service.

Cette thèse explore des pistes d'amélioration du système de trafic aérien dans l'espace océanique de l'Atlantique Nord (NAT). D'abord, on considère le système actuel, où les avions suivent les rails prédefinis. On favorise les re-routages entre rails, diminuant la congestion dans l'espace continental. On applique des méthodes stochastiques d'optimisation pour trouver une configuration de vols sans conflits avec la séparation reduite entre aéronefs. Ensuite, on simule la planification des trajectoires avec le Wind Networking (WN). La source prinicipale des erreurs dans la prédiction de trajectoires étant l'incertitude dans la prévision du vent, le WN permet aux avions d'échanger leurs vents mesurés afin d'ajuster leurs prédictions. Enfin, on introduit le concept de free-flight dans NAT. Etant donné des trajectoires vent-optimales, on applique une méthode stochastique d'optimisation pour réduire le nombre de conflits au niveau stratégique, tout en conservant les trajectoires proches de leur optimum. Nos résultats numériques mettent en évidence plusieurs pistes pour améliorer le système de trafic aérien dans NAT, en considérant de nouvelles technologies et de nouveaux concepts. / This thesis investigates the ways to improve the air traffic system in the highly congested North Atlantic oceanic airspace (NAT). First, we consider the current system, where aircraft follow predefined NAT tracks. We favor the re-routings between tracks, decreasing congestion in pre-oceanic airspace, and apply stochastic methods of optimization to find a conflict-free flight configuration with reduced separation between aircraft. Second, we simulate trajectory prediction by Wind Networking (WN). While the main source of time prediction errors is the uncertainty in wind forecast, WN permits aircraft to exchange measured winds and adjust their predictions using this recent and accurate information. Third, we study the impact of introducing the free flight concept in NAT. We apply a stochastic method of optimization on data provided by NASA consisting of NAT flights with wind optimal trajectories. The aim is to reduce the number of conflicts on the strategic level, while keeping the trajectories close to the optimal routes. Our computational experiments show that the air traffic situation in NAT can be improved in several different ways, considering new technologies and new trajectory planning concepts.