Conflict Detection and Resolution for Future Air Transportation Management

With a Free Flight policy, the emphasis for air traffic control is shifting from active control to passive air traffic management with a policy of intervention by exception. Aircraft will be allowed to fly user preferred routes, as long as safety Alert Zones are not violated. If there is a potential conflict, two (or more) aircraft must be able to arrive at a solution for conflict resolution without controller intervention. Thus, decision aid tools are needed in Free Flight to detect and resolve conflicts, and several problems must be solved to develop such tools. In this report, we analyze and solve problems of proximity management, conflict detection, and conflict resolution under a Free Flight policy. For proximity management, we establish a system based on Delaunay Triangulations of aircraft at constant flight levels. Such a system provides a means for analyzing the neighbor relationships between aircraft and the nearby free space around air traffic which can be utilized later in conflict resolution. For conflict detection, we perform both 2-dimensional and 3-dimensional analyses based on the penetration of the Protected Airspace Zone. Both deterministic and non-deterministic analyses are performed. We investigate several types of conflict warnings including tactical warnings prior to penetrating the Protected Airspace Zone, methods based on the reachability overlap of both aircraft, and conflict probability maps to establish strategic Alert Zones around aircraft

Safety Performance of Airborne Separation: Preliminary Baseline Testing

The Safety Performance of Airborne Separation (SPAS) study is a suite of Monte Carlo simulation experiments designed to analyze and quantify safety behavior of airborne separation. This paper presents results of preliminary baseline testing. The preliminary baseline scenario is designed to be very challenging, consisting of randomized routes in generic high-density airspace in which all aircraft are constrained to the same flight level. Sustained traffic density is varied from approximately 3 to 15 aircraft per 10,000 square miles, approximating up to about 5 times today s traffic density in a typical sector. Research at high traffic densities and at multiple flight levels are planned within the next two years. Basic safety metrics for aircraft separation are collected and analyzed. During the progression of experiments, various errors, uncertainties, delays, and other variables potentially impacting system safety will be incrementally introduced to analyze the effect on safety of the individual factors as well as their interaction and collective effect. In this paper we report the results of the first experiment that addresses the preliminary baseline condition tested over a range of traffic densities. Early results at five times the typical traffic density in today s NAS indicate that, under the assumptions of this study, airborne separation can be safely performed. In addition, we report on initial observations from an exploration of four additional factors tested at a single traffic density: broadcast surveillance signal interference, extent of intent sharing, pilot delay, and wind prediction error

From Information to Choice: A Critical Inquiry Into Visualization Tools for Decision Making

In the face of complex decisions, people often engage in a three-stage process that spans from (1) exploring and analyzing pertinent information (intelligence); (2) generating and exploring alternative options (design); and ultimately culminating in (3) selecting the optimal decision by evaluating discerning criteria (choice). We can fairly assume that all good visualizations aid in the intelligence stage by enabling data exploration and analysis. Yet, to what degree and how do visualization systems currently support the other decision making stages, namely design and choice? To explore this question, we conducted a comprehensive review of decision-focused visualization tools by examining publications in major visualization journals and conferences, including VIS, EuroVis, and CHI, spanning all available years. We employed a deductive coding method and in-depth analysis to assess if and how visualization tools support design and choice. Specifically, we examined each visualization tool by (i) its degree of visibility for displaying decision alternatives, criteria, and preferences, and (ii) its degree of flexibility for offering means to manipulate the decision alternatives, criteria, and preferences with interactions such as adding, modifying, changing mapping, and filtering. Our review highlights the opportunities and challenges and reveals a surprising scarcity of tools that support all stages, and while most tools excel in offering visibility for decision criteria and alternatives, the degree of flexibility to manipulate these elements is often limited, and the lack of tools that accommodate decision preferences and their elicitation is notable. Future research could explore enhancing flexibility levels and variety, exploring novel visualization paradigms, increasing algorithmic support, and ensuring that this automation is user-controlled via the enhanced flexibility levels

Trajectory-Oriented Approach to Managing Traffic Complexity: Operational Concept and Preliminary Metrics Definition

This document describes preliminary research on a distributed, trajectory-oriented approach for traffic complexity management. The approach is to manage traffic complexity in a distributed control environment, based on preserving trajectory flexibility and minimizing constraints. In particular, the document presents an analytical framework to study trajectory flexibility and the impact of trajectory constraints on it. The document proposes preliminary flexibility metrics that can be interpreted and measured within the framework

3D-in-2D Displays for ATC.

This paper reports on the efforts and accomplishments of the 3D-in-2D Displays for ATC project at the end of Year 1. We describe the invention of 10 novel 3D/2D visualisations that were mostly implemented in the Augmented Reality ARToolkit. These prototype implementations of visualisation and interaction elements can be viewed on the accompanying video. We have identified six candidate design concepts which we will further research and develop. These designs correspond with the early feasibility studies stage of maturity as defined by the NASA Technology Readiness Level framework. We developed the Combination Display Framework from a review of the literature, and used it for analysing display designs in terms of display technique used and how they are combined. The insights we gained from this framework then guided our inventions and the human-centered innovation process we use to iteratively invent. Our designs are based on an understanding of user work practices. We also developed a simple ATC simulator that we used for rapid experimentation and evaluation of design ideas. We expect that if this project continues, the effort in Year 2 and 3 will be focus on maturing the concepts and employment in a operational laboratory settings

Conflict Resolution in Autonomous Operations Area airspace

A paradigm shift is at hand with the planned redesign of the Air Traffic Management and Air Traffic Control systems. The concept for the future air traffic system foresees that aircraft will monitor and maintain separation to each other by themselves in Autonomous Operations Area airspace. With this shift of responsibility for separation assurance from Air Traffic Control to the flight deck crews a more flexible and better airspace usage is expected. Furthermore, through the more flexible airspace usage, a gain in flight efficiency is also anticipated. In order to operate in this airspace area, aircraft are required to be equipped with a system enabling them to detect and resolve air traffic conflicts. Upon detection of a conflict with another aircraft, the system is expected to compute an alternative trajectory which guides the aircraft around the conflict and back to its original trajectory. The alternative trajectory needs to adhere to several requirements, such as being clear of conflicts and being flyable. Further requirements that are often stated are to minimise the additional fuel and time required for the resolution. This thesis is concerned with such a Conflict Detection & Resolution system. Primary focus lies on the resolution of air traffic conflicts while guaranteeing flyability and respecting the Cost Index. The Cost Index is nowadays used by the Flight Management System to optimise the flight profile in respect to the operators prioritisation of fuel-related to time-related costs. This paramter is included into the Conflict Resolution process which is based on Artificial Force Fields. Flyability of the trajectory is intended to be guaranteed through integration of a flight mechanics model. The algorithm devised in this work is validated in fast time simulations with varying Cost Index. Objects of study are the distance at the Closest Point of Approach, the integration of the Cost Index and the flyability of the resulting trajectory. The first two objects of this study will be validated through comparison of the original and updated trajectory. The new trajectory is considered conflict free if the distance at the Closest Point of Approach is sufficiently large. The lateral, vertical and temporal differences between the two trajectories are used as measures for time- and fuel-related costs. Flyability of the resulting trajectory is validated by confirming adherence to the flight envelope and the constraints given by the flight mechanics model used. The evaluation of the algorithm showed that by integration of a flight mechanics model flyability of the resulting trajectory could be assured. Regarding resolution of the conflicts, the algorithm could compute a trajectory which prevented the initially set up Mid-Air Collision between the aircraft. Though, the minimum required separation could not be achieved in all cases. The approach of integrating the Cost Index into the resolution process showed to be feasible, whereas especially regarding the speed resolution further enhancements have been found to be necessary