Service Improvement and Cost Reduction for Airlines: Optimal Policies for Managing Arrival and Departure Operations under Uncertainty

Annual U.S. air travel demand has been growing steadily by 4-5% over the last decade, and it is estimated that the demand will nearly double in the next twenty years. It has also been estimated by the International Civil Aviation Organization that global demand for commercial aircraft will increase at an average annual rate of 4.1% by 2034 (IATA, 2014). However, airport expansions and aviation infrastructure upgrades have not kept pace with the increase in air traffic demand, as only 3% of all the new airport projects around the world are planned in the U.S. (CAPA, 2015). Thus, the operation rates at existing airports are likely to increase significantly, implying a greater need to increase the utilization of currently available runway capacity. With steadily increasing demand in air traffic and limited airport capacity, delay in air traffic is ubiquitous. Approximately 25% of flights experience delays of at least 15 minutes each year, resulting in significant passenger service issues and costs to airlines and society in general. Delays constitute the top service complaint for airlines, which has implications for the society as a whole - both economically and environmentally. Flight delays also increase airline costs directly, due to associated additional fuel, crew and maintenance costs. Recent studies show that the estimated cost of air transportation delay to the American economy ranges from $32.9 billion to$41 billion a year, of which, $8 billion are direct costs to airlines (Ball et al., 2010; Ferguson et al., 2013). Noting that more than 60Arrival and departure operations inherently involve significant uncertainty. When an aircraft is approaching the runway, many factors affect its trajectory, such as weather, wind conditions, pilot behavior, aircraft weight, as well as the differences in types of aircraft and flight management systems. When an aircraft arrives at the gate, operating conditions, such as unplanned security checks, varied durations of deplaning and boarding, as well as the maintenance and fueling involved, could contribute to variations of actual departure time for the next flight. All of these stochastic factors involve uncertainty and they need to be taken into account while making operational decisions. On the other hand, stochastic treatment of such operational problems has not been common in the literature due to difficulties associated with the characterization of uncertainty and the computational tractability. I argue in this thesis that, with recent advances in computing power and data analysis tools, such stochastic treatments are more amenable for practical use. To this end, I study four novel operational problems related to flight arrivals and departures at airports under the uncertainty of operating conditions, and demonstrate the potential value that can be generated through stochastic models within the context of airline and airport operations. The problems I study involve both strategic and tactical decisions for airline service improvement and cost reduction. The first two problems consider managing arrival operations at airports, while the last two problems focus on departure operations. In the first and second problems, I focus on arrival operations in the context of optimized profile descent (OPD), which is a novel arrival procedure for the Next Generation Air Transportation System. In the first problem, I identify policies for managing arrival operations at the tactical level by developing a stochastic dynamic programming framework to manage the sequencing and separation of flights. I find that simple calculation based measures can be used as optimal decision rules during such operations, and that the expected annual savings can be around$29 million if such implementations are adapted by major airports in the U.S. Of these savings, $24 million are direct savings for airlines due to reduced fuel usage, corresponding to a potential savings of 10-15In the second problem, I study the optimal design of arrival traffic management systems at airports at the strategic level. I claim that implementation of OPD operations requires effective metering configurations at airports due to the increased role of uncertainty in aircraft trajectories during descent. I develop stochastic models to further increase the value of OPD operations over conventional arrival procedures by optimizing metering point configurations, which include identification of the optimal number and locations of metering points to use. I provide numerical results based on actual traffic information at major U.S. airports, which indicate that the total potential savings in the top ten major airports could be up to$22 million per year if the proposed policies are implemented. I also find that the optimal metering configurations are mostly robust under different operating conditions. In addition, my results suggest that early spacing adjustments near the top of descent (TOD) are of more value for larger volumes of air traffic. In the third and fourth problems, I study optimal departure operations at airports under the context of departure metering, which is an airport surface management procedure that limits the number of aircraft on the runway by holding aircraft at a predesigned metering area. More specifically, in the third problem, I develop a stochastic dynamic programming framework for tactical management of pushback operations at gates and for determining the optimal number of aircraft to be directed to the runway from the metering areas. I introduce four easy-to-implement practical departure metering policies and implement a comparative analysis between these practical policies and the optimal numerical solutions. I also implement sensitivity analysis of the departure metering policies over state variable values. In the fourth problem, I study the optimal metering area capacity at the strategic level. Building on the dynamic programming framework mentioned in the third problem, I identify the optimal metering area capacity using marginal analysis to minimize expected overall costs. Numerical simulations are implemented and potential savings are identified for sample U.S. airports based on varying capacity levels. The optimal metering area capacity is then determined based on the numerical implementations to further improve overall efficiency and sustainability of departure operations. I also analyze the benefits to airlines in terms of annual savings due to such policies, and find that the annual savings could be $31 million if the optimal departure metering policies are implemented at the top ten major airports in the U.S. Overall, as one of the few studies on stochasticity in arrival and departure operations, I derive both tactical and strategic policies to improve efficiency and sustainability for airlines and the society, which can enhance service quality and strengthen market position for the airlines involved

Traffic synchronization with controlled time of arrival for cost-efficient trajectories in high-density terminal airspace

The growth in air traffic has led to a continuously growing environmental sensitivity in aviation, encouraging the research into methods for achieving a greener air transportation. In this context, continuous descent operations (CDOs) allow aircraft to follow an optimum flight path that delivers major environmental and economic benefits, giving as a result engine-idle descents from the cruise altitude to right before landing that reduce fuel consumption, pollutant emissions and noise nuisance. However, this type of operations suffers from a well-known drawback: the loss of predictability from the air traffic control (ATC) point of view in terms of overfly times at the different waypoints of the route. In consequence, ATC requires large separation buffers, thus reducing the capacity of the airport. Previous works investigating this issue showed that the ability to meet a controlled time of arrival (CTA) at a metering fix could enable CDOs while simultaneously maintaining airport throughput. In this context, more research is needed focusing on how modern arrival managers (AMANs)—and extended arrival managers (E-AMANs)—could provide support to select the appropriate CTA. ATC would be in charge to provide the CTA to the pilot, who would then use four-dimensional (4D) flight management system (FMS) trajectory management capabilities to satisfy it. A key transformation to achieve a more efficient aircraft scheduling is the use of new air traffic management (ATM) paradigms, such as the trajectory based operations (TBO) concept. This concept aims at completely removing open-loop vectoring and strategic constraints on the trajectories by efficiently implementing a 4D trajectory negotiation process to synchronize airborne and ground equipment with the aim of maximizing both flight efficiency and throughput. The main objective of this PhD thesis is to develop methods to efficiently schedule arrival aircraft in terminal airspace, together with concepts of operations compliant with the TBO concept. The simulated arrival trajectories generated for all the experiments conducted in this PhD thesis, to the maximum possible extent, are considered to be energy-neutral CDOs, seeking to reduce the overall environmental impact of aircraft operations in the ATM system. Ultimately, the objective of this PhD is to achieve a more efficient arrival management of traffic, in which higher levels of predictability and similar levels of capacity are achieved, while the safety of the operations is kept. The designed experiments consider a TBO environment, involving a high synchronization between all the involved actors of the ATM system. Higher levels of automation and information sharing are expected, together with a modernization of both current ATC ground-support tools and aircraft FMSs to comply with the new TBO paradigm.L’increment de tràfic aeri ha portat a una major sensibilitat mediambiental en l’aviació, motivant la recerca en mètodes per aconseguir un transport aeri més ecològic. En aquest context, les operacions de descens continu (CDOs) permeten a les aeronaus seguir una trajectòria que aporta grans beneficis econòmics i ambientals, donant com a resultat descensos amb els motors al ralentí des de l’altitud de creuer fins just abans d’aterrar. Aquestes trajectòries redueixen el consum de combustible, les emissions contaminants i el soroll generat per les aeronaus. No obstant això, aquest tipus d’operacions té un gran desavantatge: la pèrdua de predictibilitat des del punt de vista del controlador aeri (ATC) en termes de temps de pas als diferents punts de la ruta. Com a conseqüència, l’ATC necessita assignar una major separació entre les aeronaus, la qual cosa comporta una reducció en la capacitat de l’aeroport. Estudis previs investigant aquest problema han demostrat que la capacitat de complir amb un temps controlat d’arribada (CTA) a un punt de la ruta (utilitzat per seqüenciar les aeronaus) podria habilitar les CDOs tot mantenint la capacitat de l’aeroport. En aquest context, es necessita investigar més en com els gestors d’arribades (AMANs) i els gestors d’arribades ampliats (E-AMANs) podrien donar suport en la selecció de la CTA més adequada. L’ATC seria l’encarregat d’enviar la CTA al pilot, el qual, per tal de complir amb la CTA, faria servir la capacitat de gestió de trajectòries d’un sistema de gestió de vol (FMS) de quatre dimensions (4D). Una transformació clau per aconseguir una gestió més eficient del tràfic d’arribada és l’ús de nous paradigmes de gestió del tràfic aeri (ATM), com per exemple el concepte d’operacions basades en trajectòries (TBO). Aquest concepte té com a objectiu eliminar completament de les trajectòries la vectorització en “bucle obert” i les restriccions estratègiques. Per aconseguir-ho, es proposa implementar de manera eficient una negociació de la trajectòria 4D, amb l’objectiu de sincronitzar l’equipament de terra amb el de l’aeronau, maximitzant d’aquesta manera l’eficiència dels vols i la capacitat del sistema. El principal objectiu d’aquest doctorat és desenvolupar mètodes per gestionar aeronaus de manera eficient en espai aeri terminal, juntament amb conceptes d’operacions que compleixin amb el concepte de TBO. Les trajectòries d’arribada simulades per tots els experiments definits en aquesta tesi doctoral, en la mesura que s’ha pogut, són CDOs d’energia neutral. D’aquesta manera, la idea és reduir el màxim possible l’impacte mediambiental de les operacions aèries al sistema ATM. En definitiva, l’objectiu d’aquest doctorat és aconseguir una gestió del tràfic d’arribada més eficient, obtenint una major predictibilitat i capacitat, i assegurant que la seguretat de les operacions es manté. Els experiments dissenyats consideren una situació on el concepte de TBO és present, el que comporta una sincronització elevada entre tots els actors implicats en el sistema ATM. Així mateix, s’esperen nivells majors d’automatització i de compartició d’informació, juntament amb una modernització de les eines de suport en terra a l’ATC i dels FMSs de les aeronaus, tot amb l’objectiu de complir amb el nou paradigma de TBO.El incremento de tráfico aéreo ha llevado a una mayor sensibilidad medioambiental en la aviación, motivando la investigación de métodos para conseguir un transporte aéreo más ecológico. En este contexto, las operaciones de descenso continuo (CDOs) permiten a las aeronaves seguir una trayectoria que aporta grandes beneficios económicos y ambientales, dando como resultado descensos con los motores al ralentí desde la altitud de crucero hasta justo antes de aterrizar. Estas trayectorias reducen el consumo de combustible, las emisiones contaminantes y el ruido generado por las aeronaves. No obstante, este tipo de operaciones tiene una gran desventaja: la pérdida de predictibilidad desde el punto de vista del controlador aéreo (ATC) en términos de tiempos de paso en los diferentes puntos de la ruta. Como consecuencia, el ATC necesita asignar una mayor separación entre las aeronaves, lo cual comporta una reducción en la capacidad del aeropuerto. Estudios previos investigando este problema han demostrado que la capacidad de cumplir con un tiempo controlado de llegada (CTA) en un punto de la ruta (utilizado para secuenciar las aeronaves) podría habilitar las CDOs manteniendo al mismo tiempo la capacidad del aeropuerto. En este contexto, es necesario investigar más en cómo los gestores de llegadas (AMANs)—y los gestores de llegadas extendidos (E-AMANs)—podrían dar soporte en la selección de la CTA más adecuada. El ATC sería el encargado de enviar la CTA al piloto, el cual, para cumplir con la CTA, usaría la capacidad de gestión de trayectorias de un sistema de gestión de vuelo (FMS) de cuatro dimensiones (4D). Una transformación clave para conseguir una gestión más eficiente del tráfico de llegada es el uso de nuevos paradigmas de gestión del tráfico aéreo (ATM), como por ejemplo el concepto de operaciones basadas en trayectorias (TBO). Este concepto tiene como objetivo eliminar completamente de las trayectorias la vectorización en “bucle abierto” y las restricciones estratégicas. Para conseguirlo, se propone implementar de manera eficiente una negociación de la trayectoria 4D, con el objetivo de sincronizar el equipamiento de tierra con el de la aeronave, maximizando de esta manera la eficiencia de los vuelos y la capacidad del sistema. El principal objetivo de este doctorado es desarrollar métodos para gestionar aeronaves de manera eficiente en espacio aéreo terminal, junto con conceptos de operaciones que cumplan con el concepto de TBO. Las trayectorias de llegada simuladas para todos los experimentos definidos en esta tesis doctoral, en la medida de lo posible, son CDOs de energía neutra. De esta manera, la idea es reducir lo máximo posible el impacto medioambiental de las operaciones aéreas en el sistema ATM. En definitiva, el objetivo de este doctorado es conseguir una gestión del tráfico de llegada más eficiente, obteniendo una mayor predictibilidad y capacidad, y asegurando que la seguridad de las operaciones se mantiene. Los experimentos diseñados consideran una situación xxi donde el concepto de TBO está presente, lo que comporta una sincronización elevada entre todos los actores implicados en el sistema ATM. Asimismo, se esperan mayores niveles de automatización y de compartición de información, junto con una modernización de las herramientas de soporte en tierra al ATC y de los FMSs de las aeronaves, todo con el objetivo de cumplir con el nuevo paradigma de TBO. Primero de todo, se define un marco para la optimización de trayectorias utilizado para generar las trayectorias simuladas para los experimentos definidos en esta tesis doctoral. A continuación, se evalúan los beneficios de volar CDOs de energía neutra comparándolas con trayectorias reales obtenidas de datos de vuelo históricos. Se comparan dos fuentes de datos, concluyendo cuál es la más adecuada para estudios de eficiencia en espacio aéreo terminal. Las CDOs de energía neutra son el tipo preferido de trayectorias desde un punto de vista medioambiental pero, dependiendo de la cantidad de tráfico, podría ser imposible para el ATC asignar una CTA que pueda ser cumplida por las aeronaves mientras vuelan la ruta de llegada publicada. En esta tesis doctoral, se comparan dos estrategias con el objetivo de cumplir con la CTA asignada: volar CDOs de energía neutra por rutas más largas/cortas o volar descensos con el motor accionado por la ruta publicada. Para ambas estrategias, se analiza la sensibilidad del consumo de combustible a diferentes parámetros, como la altitud inicial de crucero o la velocidad del viento. Finalmente, en esta tesis doctoral se analizan dos estrategias para gestionar de manera eficiente el tráfico de llegada en espacio aéreo terminal. Primero, se utiliza una estrategia provisional a medio camino entre la negociación completa de trayectorias 4D y la vectorización en “bucle abierto”: se propone una metodología para gestionar de manera eficaz tráfico de llegada donde las aeronaves vuelan CDOs de energía neutra en un procedimiento de navegación de área (RNAV) conocido como trombón. A continuación, se propone una nueva metodología para generar rutas de llegada dinámicas que se adaptan automáticamente a la demanda actual de tráfico. De igual manera, se aplican CDOs de energía neutra a todo el tráfico de llegada. Hay diferentes factores a considerar que podrían limitar los beneficios de las soluciones propuestas. La cantidad y distribución del tráfico de llegada tiene un gran efecto sobre los resultados obtenidos, limitando en algunos casos una gestión eficiente de las aeronaves de llegada. Además, algunas de las soluciones propuestas comportan elevadas cargas computacionales que podrían limitar su aplicación operacional, motivando mayor investigación en el futuro con el fin de optimizar los modelos y metodologías utilizados. Finalmente, permitir a algunos aviones volar descensos con el motor accionado podría facilitar la gestión de las aeronaves de llegada en los experimentos que se centran en el procedimiento de trombón y en la generación de rutas de llegada dinámicas.Postprint (published version

A Concept for Robust, High Density Terminal Air Traffic Operations

This paper describes a concept for future high-density, terminal air traffic operations that has been developed by interpreting the Joint Planning and Development Office s vision for the Next Generation (NextGen) Air Transportation System and coupling it with emergent NASA and other technologies and procedures during the NextGen timeframe. The concept described in this paper includes five core capabilities: 1) Extended Terminal Area Routing, 2) Precision Scheduling Along Routes, 3) Merging and Spacing, 4) Tactical Separation, and 5) Off-Nominal Recovery. Gradual changes are introduced to the National Airspace System (NAS) by phased enhancements to the core capabilities in the form of increased levels of automation and decision support as well as targeted task delegation. NASA will be evaluating these conceptual technological enhancements in a series of human-in-the-loop simulations and will accelerate development of the most promising capabilities in cooperation with the FAA through the Efficient Flows Into Congested Airspace Research Transition Team

Optimized Route Capability (ORC) Intelligent Offloading of Congested Arrival Routes

The Optimized Route Capability (ORC) concept is designed to enable intelligent offloading of congested arrival routes. When ORC predicts arrival route congestion as projected excess arrival meter fix delay, automation offers decision support to traffic managers by identifying candidate flights to strategically reroute to alternate meter fixes and alleviate the congestion. This concept was applied to a model of arrival operations into Houston International Airport. An arrival rush from the Northeast was simulated in fast-time to analyze ORC algorithm behavior. The results demonstrate how strategically rerouting a few flights to alternate meter fixes not only has the potential to manage meter fix delay (and possibly the need for traffic management initiatives applied upstream), but may also increase airport capacity utilization and reduce total flight delay

Investigation, Modeling, and Analysis of Integrated Metroplex Arrival and Departure Coordination Concepts

This work involves the development of a concept that enhances integrated metroplex arrival and departure coordination, determines the temporal (the use of time separation for aircraft sharing the same airspace resources) and spatial (the use of different routes or vertical profiles for aircraft streams at any given time) impact of metroplex traffic coordination within the National Airspace System (NAS), and quantifies the benefits of the most desirable metroplex traffic coordination concept. Researching and developing metroplex concepts is addressed in this work that broadly applies across the range of airspace and airport demand characteristics envisioned for NextGen metroplex operations. The objective of this work is to investigate, formulate, develop models, and analyze an operational concept that mitigates issues specific to the metroplex or that takes advantage of unique characteristics of metroplex airports to improve efficiencies. The concept is an innovative approach allowing the NAS to mitigate metroplex interdependencies between airports, optimize metroplex arrival and departure coordination among airports, maximize metroplex airport throughput, minimize delay due to airport runway configuration changes, increase resiliency to disruptions, and increase the tolerance of the system to degrade gracefully under adverse conditions such as weather, traffic management initiatives, and delays in general

Air Traffic Management Technology Demonstration-1 Concept of Operations (ATD-1 ConOps), Version 3.0

This document describes the goals, benefits, technologies, and procedures of the Concept of Operations (ConOps) for the Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1), and provides an update to the previous versions of the document [ref 1 and ref 2]

Implementation of a point merge system based arrival at Berlin-Schönefeld airport

This project assesses the implementation of an innovative arrival procedure, called Point Merge System (PMS), at Berlin-Schönefeld airport. The viability of performing continuous descend operations (CDO) in such kind of system has been addressed. The PMS reduces the delay of aircraft through a better arrival flow merge and it reduces the environmental impact of the flights since they stay less time on air. Furthermore, CDOs allow aircraft to perform more efficient descents, with a reduction in both fuel consumption and noise nuisance. A design of a PMS has been proposed for the runway 07L of Berlin-Schönefeld airport using the current STAR. Since the arrival traffic for this runway merges at one IAF for the north arrivals and another for the south ones, it has been decided to apply a single PMS composed by two arcs; one will be used by the north traffic and the other one by the south traffic. In this design it has been taken into consideration all the regulations and measures imposed by EUROCONTROL in order to keep the safety of the operations. Finally, it has been concluded that a PMS could be implemented at Berlin-Schönefeld. In this project the effect of several parameters on the efficiency when flying CDOs has been studied. The trajectories needed for these computations have been generated with a trajectory optimizer where the aircraft performance model is obtained from the Base of Aircraft Data (BADA) by EUROCONTROL. The results obtained show that the higher the cost index the higher the speed of the aircraft is, which means an earlier time of arrival at the runway; however, the fuel consumption increases as well. Regarding the fuel consumption, it can be said that given the fact that the aircraft perform CDOs a better fuel efficiency is achieved than with conventional procedures. To sum up, the implementation of a PMS procedure at Berlin-Schönefeld is possible and would give many benefits to the airport and the airlines involved.En aquest projecte s’ha estudiat i proposat un disseny per la implementació d’un nou procediment d’arribades anomenat Point Merge System (PMS) a l’aeroport de Berlin-Schönefeld, per tal d’estudiar la possibilitat de permetre a les aeronaus realitzar operacions de descens continu (CDO). El PMS permet reduir les esperes dels avions mitjançant una millor fusió del flux de vols d’arribada; conseqüentment, es redueix l’impacte mediambiental dels vols donat que estan menys temps a l’aire. A més, les CDOs permeten a les aeronaus fer descensos molt més eficients, reduint el consum de combustible i el soroll. Un disseny de PMS s’ha proposat per la pista 07L de l’aeroport de Berlin-Schönefeld aprofitant la STAR actual. Tenint en compte que el tràfic d’arribada per aquesta pista es fusiona a un IAF per totes les arribades del nord i en un altre IAF per les de sud, s’ha decidit aplicar un únic PMS composat per dos arcs, un serà utilitzat pel tràfic del nord i l’altre pel tràfic del sud. En aquest disseny s’ha tingut en compte totes les mesures i regulacions imposades per EUROCONTROL per tal d’assegurar la seguretat en les operacions. Finalment s’ha pogut concloure que l’aeroport de Berlin-Schönefeld està capacitat per la implementació d’un PMS i poder beneficiar-se dels seus avantatges. En aquest treball també s’ha estudiat l’efecte de diferents paràmetres sobre la eficiència al volar CDOs. Les trajectòries necessàries per aquests càlculs s’han generat amb un optimitzador de trajectòries on el model de performances dels avions s’ha obtingut del Base of Aircraft Data (BADA) d’EUROCONTROL. Els resultats obtinguts mostren que a mida que l’aeronau vola amb un cost índex més elevat la velocitat augmenta, arribant així abans a la pista d’aterratge, però el consum de fuel també augmenta. Quant al consum de fuel, es pot concloure que donat que els avions realitzen CDOs s’aconsegueix una molt millor eficiència de combustible respecte als procediments convencionals. Per resumir, la implementació d’un PMS a l’aeroport de Berlin-Schönefeld és possible i permetria a l’aeroport i a les aerolínies beneficiar-se de tots els seus avantatges

Conflict free trajectory optimisation for complex departure procedures

Peer ReviewedPostprint (published version

Optimal trajectory management for aircraft descent operations subject to time constraints

The growth in traffic increased the pressure on the environmental sustainability of air transport. In this context, many research effort has been devoted to minimise the environmental impact in the different phases of flight. Continuous descent operations, ideally performed with the engines at idle from the cruise altitude to right before landing, have shown to reduce fuel, noise nuisance and gaseous emissions if compared to conventional descents. However, this type of operations suffer from a well known drawback: the loss of predictability from the air traffic control point of view in terms of overfly times at the different waypoints of the route. Due to this loss of predictability, air traffic controllers require large separation buffers, thus reducing the capacity of the airport. Previous works investigating this issue showed that the ability to meet a controlled time of arrival at a metering fix could enable continuous descent operations while simultaneously maintaining airport throughput. In this context, the planning and guidance functions of state-of-the-art flight management systems need to be modernised. On-board trajectory planners capable to generate an optimal trajectory plan satisfying time constraints introduced during the flight are seldom, mainly because the real-time optimisation of aircraft trajectories is still elusive. Furthermore, the time scale and spatial resolution of the wind forecasts used by these trajectory planners are far from being adequate to generate accurate flight time predictions. Finally, there exist guidance strategies capable to accurately comply with time constraints enforced at a certain fix in the trajectory plan, yet they are not specifically designed to minimise the environmental impact. This PhD thesis aims at investigating fast optimisation techniques to enable real-time updates of the optimal trajectory plan subject to time constraints during the descent; wind networking concepts to generate more accurate and up-to-date wind forecasts and, consequently, time predictions; and more robust an efficient guidance strategies to reduce the environmental impact at the maximum extent while complying with the time constraints of the trajectory plan. First, the feasible time window at a metering fix that could be achieved during a descent requiring neither thrust nor speed brakes usage is quantified as a function of the aircraft states (altitude, distance to the metering fix and airspeed), aiming to assess the feasibility of guidance strategies that take advantage of time and energy management concepts. Then, the performance of four of these guidance strategies is compared in terms of environmental impact mitigation and ability to satisfy operational constraints. Results from the comparison reveal that model predictive control, a strategy based on a frequent re-calculation of the optimal trajectory plan during the execution of the descent, is the most robust in terms of energy and time deviation at the metering fix, providing at the same time excellent environmental impact mitigation figures. However, the execution time required to solve a rigorous trajectory optimisation problem at each re-calculation instant remains a critical limitation for practical applications. In order to address this issue, a variant of the model predictive control strategy that allows for fast updates of the optimal trajectory plan based on parametric sensitivities is proposed, which shows analogous results yet halving the time needed to update the optimal trajectory plan. Finally, the potential benefits of using wind observations broadcast by nearby aircraft to reconstruct the wind profile downstream right before updating the optimal trajectory plan when using model predictive control is also investigated. Promising results show that the combination of model predictive control with wind networking concepts could enable optimal descents without degrading the capacity of the airport.El creixement del trànsit ha augmentat la pressió sobre la sostenibilitat ambiental del transport aeri. En aquest àmbit s'han dedicat molts esforços en recerca per reduir l'impacte ambiental en les diferents fases del vol. Les operacions de descens continu, en les quals l'aeronau descendeix amb els motors a ralentí des de l'altitud de creuer fins just abans d'aterrar, han demostrat ser una solució atractiva per reduir el combustible, el soroll i les emissions en la fase de descens. Desafortunadament, aquest tipus d'operacions tenen un inconvenient molt important: la pèrdua de predictibilitat des del punt de vista dels controladors de trànsit aeri, en termes de temps de sobrevol als diferents punts de pas de la ruta. Per aquesta raó, els controladors necessiten aplicar més separació entre aeronaus, reduint així la capacitat de l'aeroport. Treballs anteriors han demostrat que si les aeronaus fossin capaces de satisfer restriccions de temps de sobrevol a un o més punts de pas, seria possible implementar operacions de descens continu sense degradar la capacitat de l'aeroport. Malauradament, avui en dia existeixen pocs sistemes de gestió de vol capaços de generar trajectòries òptimes que satisfacin restriccions de temps, principalment perquè l’optimització de trajectòries en temps real continua sent una tasca difícil. A més, la resolució espacial i temporal dels models de vent utilitzades per els planificadors de trajectòria no son suficients per generar prediccions de temps de sobrevol prou fiables. Finalment, les estratègies de guiatge que fins i tot avui en dia permetrien satisfer amb exactitud restriccions de temps de sobrevol, no estan dissenyades específicament per minimitzar l’impacte ambiental. Aquesta tesi té com a objectiu explorar algoritmes de d'optimització ràpids i robustos que permetin actualitzar la trajectòria òptima en temps real durant l'execució del descens, satisfent al mateix temps restriccions de temps de sobrevol; també s'investigaran nous conceptes de que permetin generar models de vent molt exactes a partir d'observacions emeses per aeronaus veïnes; i estratègies de guiatge més intel·ligents que minimitzin l'impacte ambiental de les operacions de descens continu subjectes a restriccions de temps de sobrevol. En primer lloc, es quantifica la finestra de temps disponible al punt on s'aplica la restricció de temps de sobrevol, en funció dels estats de l'aeronau (altitud, velocitat i distància al punt) i assumint que els motors es mantenen ralentí i que no s'utilitzen aerofrens durant tot el descens. Els resultats de l'experiment indiquen que es podrien utilitzar estratègies de guiatge que gestionessin l'energia cinètica i potencial de l'aeronau per satisfer restriccions de temps sense necessitat de gastar més combustible. A continuació, es compararen quatre d'aquestes estratègies. Els resultats d'aquests segon experiment indiquen que el control predictiu, una estratègia que contínuament actualitza la trajectòria òptima durant el descens, es molt robusta en termes d'errors de temps i energia, i que també redueix l'impacte ambiental. Malauradament, es tarda massa a actualitzar la trajectòria òptima cada cop que s’actualitza, fet que limita la implementació d'aquesta estratègia. Per tal d'afrontar aquesta limitació, es proposa una variant que utilitza sensitivitats paramètriques per reduir el temps d'execució a l'hora d'actualitzar la trajectòria òptima, sense degradar significativament la seva exactitud. Finalment, s'investiguen els possibles beneficis d'aprofitar observacions de vent enviades per les aeronaus del volant per millorar el model de vent i, conseqüentment, l'exactitud de la trajectòria calculada. Resultats prometedors demostren que si s’implementés model predictiu com a estratègia de guiatge i les aeronaus cooperessin per compartir observacions de vent, es reduiria l'impacte ambiental sense degradar la capacitat de l'aeroport.Postprint (published version

A Fast and Flexible Aircraft Trajectory Predictor and Optimiser for ATM Research Applications

Trajectory prediction and optimisation algorithms will be the keystone for a successful trajectory based operations concept implementation, where accurate predictions and optimal trajectories will be needed for a wide variety of look-ahead times and operational contexts. The main goal of this paper is to present the architecture and capabilities of an aircraft trajectory prediction and optimisation framework suitable for various air traffic management research applications. The flexibility of this framework, called DYNAMO, allows for an easy implementation and assessment of actual and future concepts of operation, considering at the same time realistic weather data and aircraft performance models. In addition, its design enables the use for real-time applications and when a large set of trajectories needs to be rapidly generated for simulation and benchmarking purposes. The performance of the frameworPeer ReviewedPostprint (published version