The aim of this study was to investigate how air traffic controllers cope with stress and also to determine whether there were statistically significant differences in the coping behaviour of air traffic control staff from different groups. The study was conducted on a sample of Air Traffic Controllers who control civilian aircraft in the South African airspace. The coping resources inventory (CRI) assessment was used to collect data and analysed to determine how controllers cope with stress and whether there are differences in the coping behaviour of air traffic control staff from different groups. The results showed that air traffic controllers use emotional coping resources to cope with stressful work situations and make less use of cognitive coping resources. The results also showed that there were no statistically significant differences in the coping behaviour of air traffic control staff from different groups. / Industrial and organisational psychology / M.A. (Industrial and Organisational Psychology)

La gestion des flux de trafic aérien (ATFM) cherche à structurer le trafic de manière à réduire la congestion dans l'espace aérien. La congestion étant causée par les avions volant dans les mêmes portions de l'espace aérien en même temps, l'ATFM organise le trafic dans les dimensions spatiales (ex. le réseau de routes) et dans la dimension temporelle (ex. séquencement et fusion de flux d'avions atterrissant ou décollant aux aéroports). L'objectif de cette thèse est de développer une méthodologie qui permet au trafic aérien de s'auto-structurer dans les dimensions spatiales et temporelle quand la demande est élevée. Cette structuration disparait quand la demande diminue. Pour remplir cet objectif, un système multi-agents a été développé, dans lequel les avions coopèrent pour structurer le trafic. Les systèmes multi-agents possèdent plusieurs avantages, incluant une bonne résilience aux perturbations, la résilience étant la capacité du système à modifier ses décisions de manière à retrouver un état stable après l'occurrence d'une perturbation dans son environnement. Dans ce système, trois algorithmes sont implémentés, visant à réduire la com- plexité du trafic de trois manières différentes. Le premier algorithme permet aux agents avions volant sur un réseau de route de réguler leur vitesse de manière à ré- duire le nombre de conflits, un conflit se produisant quand deux avions ne respectent pas les normes de séparation. Le deuxième algorithme permet aux avions de résoudre les conflits quand le trafic n'est pas structuré par un réseau de routes. Le troisième algorithme crée des réseaux de routes locaux temporaires pour structurer le trafic. Les trois algorithmes implémentés dans ce système multi-agents permet de réduire la complexité globale du trafic, qui devient plus simple à gérer pour les contrôleurs aériens. Ces algorithmes sont appliqués à des exemples réalistes et sont capables de structurer le trafic de manière résiliente. / Air Traffic Flow Management (ATFM) aims at structuring traffic in order to reduce congestion in airspace. Congestion being linked to aircraft located at the same position at the same time, ATFM organizes traffic in the spatial dimension (e.g. route network) and in the time dimension (e.g. sequencing and merging of aircraft flows taking off or landing at airports). The objective of this thesis is to develop a methodology that allows the traffic to self-organize in the time and space dimensions when demand is high. This structure disappears when the demand diminishes. In order to reach this goal, a multi-agent system has been developed, in which aircraft cooperate to structure traffic. Multi-agent systems have several advantages, including a good resilience when confronted with disruptive events, resilience being the ability of the system to adapt its decisions in order to get back to a stable state when confronted to a disruption in its environment. In this system, three algorithms have been implemented, aiming at reducing traffic complexity in three different ways. The first algorithm allows aircraft agents flying on a route network to regulate speed in order to reduce the number of conflicts, a conflict occurring when two aircraft do not respect separation norms. The second algorithm allows aircraft to solve conflicts when the traffic is not structured by a route network. The third algorithm creates temporary local route networks allowing to structure traffic. The three algorithms implemented in this multi-agent system allow to decrease overall traffic complexity, which becomes easier to manage by air traffic controllers. This algorithm was applied on realistic examples and was able to structure traffic in a resilient way.

In response to the unparalleled growth of demand for air traffic during the past few decades, the Federal Aviation Administration (FAA) launched the Next Generation Air Transportation (NextGen) program to restructure the National Airspace System (NAS). Among the research is the focus on direct, wind optimal routing using geodesic routes and flight operations that do not depend solely on ground based navigation aids (NAVAID) and a fixed airspace structure. While technologies, such as the Global Positioning System (GPS), exist to locate an aircraft at higher degrees of resolution with a larger coverage, the way in which this information is conveyed is long and cumbersome. Therefore, new ways to describe the airspace is desired. The thesis presents the results of an experimental investigation into three alternatives to fix/route and GPS methods. The first method is the Navigation Reference System (NRS) using an absolute grid based strategy that has been recently implemented in limited portions of the United States airspace. The second method, the Military Grid Reference System (MGRS), is also a grid based system, and it is used by NATO, but it has not been applied to the air traffic control context. The third alternative is Point Relation Navigation (PRN), which uses a single point of reference within each Air Route Traffic Center (ARTCC) airspace and acts as a hybrid of coordinate and radial fixes. 21 airline dispatchers from a single major U.S air carrier participated in an online assessment of the five methods above through specific tasks. Results indicate that most participants prefer the fix/route system over the others, followed closely by the PRN method. However, there were varying results across all of the methods in terms of speed and accuracy of completing the tasks. This study incites further interest in strategies to describe aircraft routes operating in a more flexible airspace.

The aim of this study was to investigate how air traffic controllers cope with stress and also to determine whether there were statistically significant differences in the coping behaviour of air traffic control staff from different groups. The study was conducted on a sample of Air Traffic Controllers who control civilian aircraft in the South African airspace. The coping resources inventory (CRI) assessment was used to collect data and analysed to determine how controllers cope with stress and whether there are differences in the coping behaviour of air traffic control staff from different groups. The results showed that air traffic controllers use emotional coping resources to cope with stressful work situations and make less use of cognitive coping resources. The results also showed that there were no statistically significant differences in the coping behaviour of air traffic control staff from different groups. / Industrial and organisational psychology / M.A. (Industrial and Organisational Psychology)

In my Master´s thesis I am concerned with the questions of the human factor in air traffic control. The work is mainly focused on the air traffic controller and discusses the influences that directly or indirectly affect the air traffic controller. Considerable attention is paid to the errors that may occur during the management, their analysis and proposals for their elimination, respectively their complete disposal. The main idea is to understand the thinking of the air traffic controller as the human element in an organization and applying theories to reduce the errors in the air traffic control.

In my Master´s thesis I am concerned with the questions of the human factor in air traffic control. The work is mainly focused on the air traffic controller and discusses the influences that directly or indirectly affect the air traffic controller. Considerable attention is paid to the errors that may occur during the management, their analysis and proposals for their elimination, respectively their complete disposal. The main idea is to understand the thinking of the air traffic controller as the human element in an organization and applying theories to reduce the errors in the air traffic control.

<p>Multiple target tracking (MTT) is a major area that occurs in a variety of real world systems. The problem involves the detection and estimation of an unknown number of targets within a scenario space given a sequence of noisy, incomplete measurements. The classic approach to MTT performs data association between individual measurements, however, this step is a computationally complex problem. Recently, a series of algorithms based on Random Finite Set (RFS) theory, that do not require data association, have been introduced. This thesis addresses some of the main deficiencies involved with RFS methods and derives key extensions to improve them for use in real world systems.\\</p> <p>The first contribution is the Weight Partitioned PHD filter. It separates the Probability Hypothesis Density (PHD) surface into partitions that represent the individual state estimates both spatially and proportionally. The partitions are labeled and propagated over several time steps to form continuous track estimates. Multiple variants of the filter are presented. Next, the Multitarget Multi-Bernoulli (MeMBer) filter is extended to allow the tracking of manoeuvring targets. A model state variable is incorporated into the filter framework to estimate the probability of each motion model. The standard implementations are derived. Finally, a new linear variant of the Intensity filter (iFilter) is presented. A Gaussian Mixture approximation provides more computationally efficient implementation of the iFilter.</p> <p>Each of the new algorithms are validated on simulated data using standard multitarget tracking metrics. In each case, the methods improve on several aspects of multitarget tracking in the real world.</p> / Doctor of Engineering (DEng)

We develop and evaluate two significant modeling concepts within the context of a large-scale Airspace Planning and Collaborative Decision-Making Model (APCDM) and, thereby, enhance its current functionality in support of both strategic and tactical level flight assessments. The first major concept is a new severe weather-modeling paradigm that can be used to assess existing tactical en route flight plan strategies such as the Flight Management System (FMS) as well as to provide rerouting strategies. The second major concept concerns modeling the mediated bartering of slot exchanges involving airline trade offers for arrival/departure slots at an arrival airport that is affected by the Ground Delay Program (GDP), while simultaneously considering issues related to sector workloads, airspace conflicts, as well as overall equity concerns among the airlines. This research effort is part of an $11.5B, 10-year, Federal Aviation Administration (FAA)-sponsored program to increase the U.S. National Airspace (NAS) capacity by 30 percent by the year 2010. Our innovative contributions of this research with respect to the severe weather rerouting include (a) the concept of "Probability-Nets" and the development of discretized representations of various weather phenomena that affect aviation operations; (b) the integration of readily accessible severe weather probabilities from existing weather forecast data provided by the National Weather Service (NWS); (c) the generation of flight plans that circumvent severe weather phenomena with specified probability levels, and (d) a probabilistic delay assessment methodology for evaluating planned flight routes that might encounter potentially disruptive weather along its trajectory. Given a fixed set of reporting stations from the CONUS Model Output Statistics (MOS), we begin by constructing weather-specific probability-nets that are dynamic with respect to time and space. Essential to the construction of the probability-nets are the point-by-point forecast probabilities associated with MOS reporting sites throughout the United States. Connections between the MOS reporting sites form the strands within the probability-nets, and are constructed based upon a user-defined adjacency threshold, which is defined as the maximum allowable great circle distance between any such pair of sites. When a flight plan traverses through a probability-net, we extract probability data corresponding to the points where the flight plan and the probability-net strand(s) intersect. The ability to quickly extract this trajectory-related probability data is critical to our weather-based rerouting concepts and the derived expected delay and related cost computations in support of the decision-making process. Next, we consider the superimposition of a flight-trajectory-grid network upon the probability-nets. Using the U.S. Navigational Aids (Navaids) as the network nodes, we develop an approach to generate flight plans that can circumvent severe weather phenomena with specified probability levels based on determining restricted, time-dependent shortest paths between the origin and destination airports. By generating alternative flight plans pertaining to specified threshold strand probabilities, we prescribe a methodology for computing appropriate expected weather delays and related disruption factors for inclusion within the APCDM model. We conclude our severe weather-modeling research by conducting an economic benefit analysis using a k-means clustering mechanism in concert with our delay assessment methodology in order to evaluate delay costs and system disruptions associated with variations in probability-net refinement-based information. As a flight passes through the probability-net(s), we can generate a probability-footprint that acts as a record of the strand intersections and the associated probabilities from origin to destination. A flight plan's probability-footprint will differ for each level of data refinement, from whence we construct route-dependent scenarios and, subsequently, compute expected weather delay costs for each scenario for comparative purposes. Our second major contribution is the development of a novel slot-exchange modeling concept within the APCDM model that incorporates various practical issues pertaining to the Ground Delay Program (GDP), a principal feature in the FAA's adoption of the Collaborative Decision-Making (CDM) paradigm. The key ideas introduced here include innovative model formulations and several new equity concepts that examine the impact of "at-least, at-most" trade offers on the entire mix of resulting flight plans from respective origins to destinations, while focusing on achieving defined measures of "fairness" with respect to the selected slot exchanges. The idea is to permit airlines to barter assigned slots at airports affected by the Ground Delay Program to their mutual advantage, with the FAA acting as a mediator, while being cognizant of the overall effect of the resulting mix of flight plans on air traffic control sector workloads, collision risk and safety, and equity considerations. We start by developing two separate slot-exchange approaches. The first consists of an external approach in which we formulate a model for generating a set of package-deals, where each package-deal represents a potential slot-exchange solution. These package-deals are then embedded within the APCDM model. We further tighten the model representation using maximal clique cover-based cuts that relate to the joint compatibility among the individual package-deals. The second approach significantly improves the overall model efficiency by automatically generating package-deals as required within the APCDM model itself. The model output prescribes a set of equitable flight plans based on admissible trades and exchanges of assigned slots, which are in addition conformant with sector workload capabilities and conflict risk restrictions. The net reduction in passenger-minutes of delay for each airline is the primary metric used to assess and compare model solutions. Appropriate constraints are included in the model to ensure that the generated slot exchanges induce nonnegative values of this realized net reduction for each airline. In keeping with the spirit of the FAA's CDM initiative, we next propose four alternative equity methods that are predicated on different specified performance ratios and related efficiency functions. These four methods respectively address equity with respect to slot-exchange-related measures such as total average delay, net delay savings, proportion of acceptable moves, and suitable value function realizations. For our computational experiments, we constructed several scenarios using real data obtained from the FAA based on the Enhanced Traffic Management System (ETMS) flight information pertaining to the Miami and Jacksonville Air Route Traffic Control Centers (ARTCC). Through our experimentation, we provide insights into the effect of the different proposed modeling concepts and study the sensitivity with respect to certain key parameters. In particular, we compare the alternative proposed equity formulations by evaluating their corresponding slot-exchange solutions with respect to the net reduction in passenger-minutes of delay for each airline. Additionally, we evaluate and compare the computational-effort performance, under both time limits and optimality thresholds, for each equity method in order to assess the efficiency of the model. The four slot-exchange-based equity formulations, in conjunction with the internal slot-exchange mechanisms, demonstrate significant net savings in computational effort ranging from 25% to 86% over the original APCDM model equity formulation. The model has been implemented using Microsoft Visual C++ and evaluated using a C++ interface with CPLEX 9.0. The overall results indicate that the proposed modeling concepts offer viable tools that can be used by the FAA in a timely fashion for both tactical purposes, as well as for exploring various strategic issues such as air traffic control policy evaluations; dynamic airspace resectorization strategies as a function of severe weather probabilities; and flight plan generation in response to various disruption scenarios. / Ph. D.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / A radar system observes an aircraft once during each scan of the airspace, and uses these observations to construct a track representing a possible route of the aircraft. However when aircraft interact closely there is the possiblility of confusing the identities of the tracks. In this thesis multiple hypothesis techniques are applied to extract an identity confidence from a track, given a set of possible tracks and observations. The system utilises numerous estimation filters internally and these are investigated and compared in detail. The Identity Confidence algorithm is tested using a developed radar simulation system, and evaluated sucessfully against a series of benchmark tests.

How do air traffic controllers, or ATCos, distribute visual attention and can it vary between controllers? In this study, using primarily eye-tracking data and a couple of on-site interviews, these questions are explored. Two ATCos, with the most similar landings, had their eye-movements recorded with Tobii pro glasses 2 and further analysed by categorizing every fixation into different areas of interest during four landings. Two more ATCos were interviewed briefly during an observational visit to the control tower. The results showed that the ATCos distributed their attention fairly equally between the outside of the control tower and the inside. When attending to something outside the runway was the focus and when attention was inside the control tower the radar was usually the focus. The ATCos differed in their attention distribution by the presumably more experienced ATCo distributing their attention more outside the control tower than the presumably less experienced ATCo.  A large number of fixations were not categorized bringing the method of dividing the ATCos eye-tracking view into areas of interest into question.