Prescriptive Analytics System for Long-Range Aircraft Conflict Detection and Resolution
Total Page：16
File Type：pdf, Size：1020Kb
In Proceedings of the 26th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems, pages 239–248, Seattle, WA, November 2018. Prescriptive Analytics System for Long-Range Aircraf Conflict Detection and Resolution Samet Ayhan∗ Pablo Costas Hanan Samet University of Maryland Boeing Research & Technology University of Maryland College Park, Maryland Europe College Park, Maryland [email protected] Madrid, Spain [email protected] [email protected] ABSTRACT 1 INTRODUCTION At the present time, there is no mechanism for Air Navigation In the present Air Trafc Management (ATM) system, Airline Op- Service Providers (ANSPs) to probe new fight plans fled by the erations Center (AOC) personnel fle a fight plan for a particular Airlines Operation Centers (AOCs) against the existing approved fight. The fled fight plan usually contains 2D coordinates of the fight plans to see if they are likely to cause conficts or bring sector fxed way points and the planned initial cruise speed and cruise trafc densities beyond control. In the current Air Trafc Control altitude in addition to their speed and level changes along the route. (ATC) operations, aircraft conficts and sector trafc densities are It does not include the time information for the way points and the resolved tactically, increasing workload and leading to potential existing information is not routinely updated by the ATM systems. safety risks and loss of capacity and efciency. Moreover, the fled fight plan is not checked against other fight We propose a novel Prescriptive Analytics System to address a plans to probe potential interference with other aircraft or iden- long-range aircraft confict detection and resolution (CDR) problem. tify sector trafc complexity before the aircraft departs. Airspace Given a set of predicted trajectories, the system declares a confict sector complexity and aircraft separation assurance are dealt with when a protected zone of an aircraft on its trajectory is infringed tactically just a few minutes before the aircraft enters the sector or upon by another aircraft. The system resolves the confict by pre- is likely to have a confict with other aircraft. scribing an alternative solution that is optimized by perturbing at It is estimated that by 2040 the USA alone can expect an in- least one of the trajectories involved in the confict. To achieve crease of more than 68% in the commercial air trafc [10]. Hence, a this, the system learns from descriptive patterns of historical tra- new concept of operations is needed to accommodate this increase jectories and pertinent weather observations and builds a Hidden in volume. To meet this challenge ahead of us, new technologies Markov Model (HMM). Using a variant of the Viterbi algorithm, and procedures for next generation ATM are being developed in the system avoids the airspace volume in which the confict is de- the context of the Next Generation Air Transportation System tected and generates a new optimal trajectory that is confict-free. (NextGen) [8] in the USA and the Single European Sky ATM Re- The key concept upon which the system is built is the assumption search (SESAR) [32] in Europe. The SESAR and NextGen concept that airspace is nothing more than horizontally and vertically con- of operations require a paradigm shift from a highly structured catenated set of spatio-temporal data cubes where each cube is and fragmented system that is heavily reliant on tactical decision considered as an atomic unit. We evaluate our system using real making and with few strategic planning functions based on un- trajectory datasets with pertinent weather observations from two certain information, to an integrated one based on collaborative continents and demonstrate its efectiveness for strategic CDR. strategic management of trajectories and information sharing [35]. In the future ATM systems to be built under NextGen and SESAR, CCS CONCEPTS the trajectory becomes the fundamental element of new sets of • Information systems → Data analytics; • Computing method- operating procedures collectively referred to as Trajectory-Based ologies → Dynamic programming for Markov decision pro- Operations (TBO). The underlying idea behind TBO is the concept cesses; • Applied computing → Aerospace; of business trajectory which is the trajectory that will best meet airline business interests. The TBO concept of operations and the KEYWORDS notion of business trajectory will result in more efcient 4D tra- jectories. Thus, the future ATM system should ofer fexibility to Prescriptive Analytics; Hidden Markov Model; Time Series accommodate business trajectories, while bearing the primary goal ∗Senior Engineer at Boeing Research & Technology. of safety in mind. Overall, the next generation ATM paradigm shift requires more safe and efcient CDR due to fact that maintaining Permission to make digital or hard copies of all or part of this work for personal or the separation minima among the vast volume of aircraft that fy classroom use is granted without fee provided that copies are not made or distributed their versions of most optimal business 4D trajectories becomes for proft or commercial advantage and that copies bear this notice and the full citation on the frst page. Copyrights for components of this work owned by others than ACM more challenging. must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, Hence, we introduce a Prescriptive Analytics System to address to post on servers or to redistribute to lists, requires prior specifc permission and/or a the long-range aircraft CDR problem. The system performs CDR in fee. Request permissions from [email protected]. SIGSPATIAL ’18, November 6–9, 2018, Seattle, WA, USA two steps: In the frst step, given a set of predicted trajectories in © 2018 Association for Computing Machinery. the form of a 4D joint spatio-temporal data cubes on a 3D grid net- ACM ISBN 978-1-4503-5889-7/18/11...$15.00 work, the system declares a confict if one of the aircraft’s predicted https://doi.org/10.1145/3274895.3274947 In Proceedings of the 26th ACM SIGSPATIAL International Conference on Advances in Geographic Information Systems, pages 239–248, Seattle, WA, November 2018. trajectory segment overlaps with the other’s protected zone at the domain and on confict (i.e., collision) detection and resolution. An same time interval in the future. Obviously, the more accurate the excellent survey of various CDR methods is presented in [13]. In predicted trajectories, the more accurate the detection of the con- this survey, Kuchar et al. propose a taxonomy to categorize the fict as the separation minima will be on the containment volume basic functions of CDR modeling methods. The proposed taxonomy of each predicted trajectory. In the second step, the system builds a includes: dimensions of state information (lateral, vertical, or three- stochastic model, HMM that learns from the historical trajectories dimensional); method of state propagation (nominal, worst-case, and their correlation with the pertinent weather parameters. Using or probabilistic); confict detection threshold; confict resolution a variant of the Viterbi algorithm, the CDR System prescribes an method (prescribed, optimized, force feld, or manual); maneuvering optimal solution by perturbing at least one of the 4D trajectories options (speed change, lateral, vertical, or combined maneuvers); involved in the confict. and management of multiple aircraft conficts (pairwise or global). In summary, the contributions of this paper are as follows: Confict detection methods can be classifed as nominal, worst- • We propose a cube-shaped protected zone surrounding each case, and probabilistic techniques. The nominal technique projects aircraft that can be expanded by joining the neighboring the current states into the future along a single trajectory without cubes horizontally and vertically, yielding a protected zone taking uncertainties into account [9, 37]. The worst-case technique with a desired size. This idea resonates with the assumption assumes that an aircraft will perform any of a set of maneuvers that an airspace is nothing more than a set of concatenated and a confict is predicted if any of the maneuvers could cause a spatio-temporal data cubes around a 3D grid network, where confict [34, 38]. The disadvantage of the worst-case technique is each cube is considered as an atomic unit. that it can declare a confict as soon as there is a minimum likelihood of a confict within the defnition of the worst-case trajectory model • We propose a scalable Prescriptive Analytics System to strate- thereby leading to false positives. The probabilistic approach ofers gically address the aircraft CDR problem. Given a set of pre- a balance between relying on either a single trajectory model as in dicted trajectories, the system declares a confict when a the nominal technique or a set of worst-case maneuvers. Instead protected zone of an aircraft on its trajectory is infringed it models uncertainties to describe potential changes in the future upon by another aircraft at the same time interval in the trajectory [14, 21, 40]. future. Upon a confict, the system executes our confict res- Once a confict has been detected, the next step in the CDR pro- olution algorithm and prescribes a solution that resolves cess is to initiate the confict resolution phase by determining the the confict by perturbing at least one of the 4D trajectories course of action. The confict resolution method and the maneuver- involved in the confict. ing options are two major factors in defning the course of action. • We conduct extensive experiments based on real trajectory Confict resolution methods can be categorized as a) prescribed, b) and weather data from two continents and demonstrate that optimized, c) force-feld, and d) manual. The prescribed resolution our CDR System can detect and resolve conficts with lateral method provides a fxed maneuver based on a set of predefned and vertical accuracies that are within the boundaries of procedures [5]. Hence, depending on the nature of the confict, the conventionally accepted minimum separation values, set predefned resolution maneuver is automatically performed, mini- by the ANSPs.