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Transportation Science Papers
- An Airspace Planning and Collaborative Decision Making Model: Part II Cost Model, Data Considerations, and Computations (2006)
In Part I of this paper, we presented a large-scale airspace-planning and collaborative decision-making (APCDM) model that is part of a Federal Aviation Administration (FAA)-sponsored effort to enhance the management of the National Airspace System (NAS). Given a set of flights that must be scheduled during some planning horizon, along with alternative surrogate trajectories for each flight, we developed a mixed-integer programming model to select a set of flight plans from among these alternatives, subject to flight safety, air-traffic control workload, and airline equity considerations. The present paper offers insights related to, and a detailed description of, implementing this APCDM model, including the development of a comprehensive cost model, a study for prescribing a set of appropriate parameter values for the overall model, and an investigation on incorporating a suitable set of valid inequalities in the model formulation. Computational results are presented based on several test cases derived from the Enhanced Traffic Management System (ETMS) data provided by the FAA. The results indicate that under plausible probabilistic trajectory error assumptions and with the incorporation of star subgraph convex hull-based valid inequalities, the model offers a viable tool that can be used by the FAA for both tactical and strategic applications.
Offical Transportation Science Reference - Full Text PDF
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- An Airspace Planning and Collaborative Decision-Making Model: Part I Probabilistic Conflicts, Workload, and Equity Considerations (2003)
We present a large–scale, airspace planning and collaborative decision–making model (APCDM) to enhance the management of the U.S. National Airspace System (NAS). Given a set of flights that must be scheduled during some planning horizon, along with alternative surrogate trajectories for each flight as prompted by various airspace restriction scenarios imposed by dynamic severe weather systems or space launch special use airspaces (SUA), we develop a mixed–integer programming model to select a set of flight plans from among these alternatives, subject to flight safety, air traffic control workload, and airline equity constraints. The model includes a three–dimensional probabilistic conflict analysis, the derivation of valid inequalities, the development of air traffic control workload metrics, and the consideration of equity among airline carriers in absorbing costs related to rerouting, delays, and possible cancellations. The resulting APCDM model has potential use for both tactical and strategic applications, such as air traffic control in response to severe weather phenomena or spacecraft launches, FAA policy evaluation (separation standards, workload restrictions, sectorization strategies), Homeland Defense contingency planning, and military air campaign planning. The model can also serve a useful role in augmenting the FAA's National Playbook of standardized flight profiles in different disruption–prone regions of the national airspace. The present paper focuses on the theory and model development; Part II of this paper will address model parameter estimations and implementation test results.
Offical Transportation Science Reference - Full Text PDF
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- An Airspace Planning Model for Selecting Flight-Plans Under Workload, Safety, and Equity Considerations (2002)
In this paper, we present an airspace planning model (APM) that has been developed for use in both tactical and strategic planning contexts under various airspace scenarios. Given a set of flights for a particular time horizon, along with (possibly several) alternative flight-plans for each flight that are based on delays and diversions, due to special-use airspace (SUA) restrictions prompted by launches at spaceports or adverse weather conditions, this model prescribes a set of flight-plans to be implemented. The model formulation seeks to minimize and delay fuel-cost-based objective function, subject to the constraints that each flight is assigned one of the designated flight-plans, and that the resulting set of flight-plans satisfies certain specified workload, safety, and equity criteria. These requirements ensure that the workload for air-traffic controllers in each sector is held under a permissible limit, that any potential conflicts are routinely resolvable, and that the various airlines involved derive equitable levels of benefits from the overall implemented schedule. To solve the resulting 0–1 mixed-integer programming problem more effectively using commercial software (e.g., CPLEX-MIP), we explore the use of reformulation techniques designed to more closely approximate the convex hull of feasible solutions to the problem. We also prescribe a polynomial-time heuristic procedure that is demonstrated to provide solutions to the problem within 0.01% of optimality. Computational results are reported on several scenarios based on actual flight data obtained from the Federal Aviation Administration (FAA) to demonstrate the efficacy of the proposed approach for air-traffic management (ATM) purposes.
Offical Transportation Science Reference - Full Text PDF
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- National Airspace Sector Occupancy and Conflict Analysis for Evaluating Scenarios Under Free-Flight Paradigm (2000)
Free-Flight is a paradigm of aircraft operations that permits the selection of
more cost-effective routes for flights rather than simple traversals between
designated way-points, from various origins to different destinations. In this
paper, we consider the effect of this paradigm on sector workloads and potential
conflicts or collision risks, based on current and projected levels of
commercial air traffic. To accomplish this task, we first develop an Airspace
Sector Occupancy Model (AOM) that identifies the occupancies of flights within
three-dimensional (possibly nonconvex) regions of space called sectors, by
utilizing an iterative procedure to trace each flight's progress through sector
modules, that constitute the sectors. Next, we develop an Aircraft Encounter
Model (AEM), which uses the information obtained from AOM to efficiently
estimate the number and nature of blind-conflicts (i.e., conflicts under no
avoidance or resolution maneuvers) resulting from a selected mix of flight
plans. Besides identifying the existence of a conflict, AEM also provides useful
information on the severity of the conflict and its geometry, such as the faces
across which an intruder enters and exits the protective shell or envelope of
another aircraft, the duration of intrusion, its relative heading, and the point
of closest approach. For purposes of evaluation and assessment, we also develop
a metric that provides a summary of the conflicts in terms of severities and
difficulty of resolution. Finally, we apply these models to real data provided
by the Federal Aviation Administration (FAA) for evaluating several Free-Flight
scenarios under wind-optimized conditions. This study constitutes the first
phase of a project undertaken by a joint FAA/Eurocontrol Collision Risk Modeling
Group to develop tasks for investigating air traffic control strategies and
related workload and collision risk consequences under various scenarios.
Follow-on work will incorporate pilot blunders, random deviations, and air
traffic control man-in-the-loop maneuvers within the context of the Free-Flight paradigm, using the basic tools developed in the present study.
Offical Transportation Science Reference - Full Text PDF
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