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Accounting for state uncertainty in collision avoidance
July 1, 2011
Journal Article
Published in:
J. Guidance, Control, and Dynamics, Vol. 34, No. 4, July-August 2011, pp. 951-960.
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Summary
An important consideration in the development of aircraft collision avoidance systems is how to account for state uncertainty due to sensor limitations and noise. However, many collision avoidance systems simply use point estimates of the state instead of leveraging the full posterior state distribution. Recently, there has been work on applying decision-theoretic methods to collision avoidance, but the importance of accommodating state uncertainty has not yet been well studied. This paper presents a computationally efficient framework for accounting for state uncertainty based on dynamic programming. Examination of characteristic encounters and Monte Carlo simulations demonstrates that properly handling state uncertainty rather than simply using point estimates can significantly enhance safety and improve robustness to sensor error.
Summary
An important consideration in the development of aircraft collision avoidance systems is how to account for state uncertainty due to sensor limitations and noise. However, many collision avoidance systems simply use point estimates of the state instead of leveraging the full posterior state distribution. Recently, there has been work on...
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Analytical workload model for estimating en route sector capacity in convective weather
June 14, 2011
Conference Paper
Published in:
9th USA/Europe Air Traffic Management Research and Development Sem., ATM 2011, 14-17 June 2011.
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We have extended an analytical workload model for estimating en route sector capacity to include the impact of convective weather. We use historical weather avoidance data to characterize weather blockage, which affects the sector workload in three ways: (1) Increase in the conflict resolution task rate via reduction in available airspace, (2) increase in the recurring task load through the rerouting of aircraft around weather, and (3) increase in the inter-sector coordination rate via reduction in the mean sector transit time. Application of the extended model to observed and forecast data shows promise for future use in network flow models.
Summary
We have extended an analytical workload model for estimating en route sector capacity to include the impact of convective weather. We use historical weather avoidance data to characterize weather blockage, which affects the sector workload in three ways: (1) Increase in the conflict resolution task rate via reduction in available...
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Estimation of potential IDRP benefits during convective weather SWAP
May 26, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-381
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This document presents a preliminary analysis of potential departure delay reduction benefits in New York as the result of the use of the Integrated Departure Route Planning (IDRP) tool during convective severe weather avoidance programs (SWAP). The analysis is based on weather impact and air traffic data from operations between May and September 2010 in the New York metroplex region. Two methodologies were employed in the analysis: "flight pool" and "resource pool." In the flight pool methodology, individual flights with excessive taxi times were identified, and opportunities to find potential alternative reroutes using information that IDRP will provide were assessed. In the resource pool methodology, route impact minutes were tallied over several days, based on the judgment of a human analysis, and opportunities to recover capacity lost to route impacts via IDRP-identified reroutes were estimated. The flight pool methodology estimated that approximately 156 hours of delay could be saved through the use of IDRP over a full SWAP season. The resource pool methodology estimated that approximately 15% of capacity lost to convective weather impacts could be recovered via IDRP-based reroutes. It should be noted that the potential benefits are based on several assumptions that are described in detail in the text of the report. The estimation of delay savings due to reroute is also speculative. It is very difficult to ascertain when the assignment of a reroute actually makes use of underutilized capacity and when the reroute simply shifts the problem from one congested resource to another. Further research is needed to develop reliable metrics that can guide the assessment of reroute impacts on overall traffic management performance.
Summary
This document presents a preliminary analysis of potential departure delay reduction benefits in New York as the result of the use of the Integrated Departure Route Planning (IDRP) tool during convective severe weather avoidance programs (SWAP). The analysis is based on weather impact and air traffic data from operations between...
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Making departure management weather impact models airspace-adaptable: adapting the New York Route Availability Planning Tool (RAPT) to Chicago departure airspace
May 26, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-378
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The Route Availability Planning Tool (RAPT) operational prototype was deployed to Chicago in the summer of 2010, the first RAPT deployment outside of the New York departure airspace for which it was originally developed. The goal of the deployment was to evaluate the adaptability of RAPT's airspace definition, departure management and weather impact models to different terminal areas throughout the National Airspace System (NAS). This report presents the results of a summer-long evaluation of the Chicago RAPT operational prototype, in which the performance of RAPT algorithms and the effectiveness of the RAPT Concept of Operations were assessed. The evaluation included observations made by researchers simultaneously stationed at O'Hare terminal (ORD), the Chicago TRACON (C90), and the Chicago Air Route Traffic Control Center (ZAU) during several days of convective weather impact and post-event analysis of air traffic data from the Enhanced Traffic Management System (ETMS) and RAPT weather impact predictions and departure management guidance. The study found that significant departure delay reduction could be achieved through the use of RAPT in Chicago, and that RAPT effectiveness in "typical" corner post airspaces like Chicago could be further increased with some modifications to the Concept of Operations, user training, and site adaptation.
Summary
The Route Availability Planning Tool (RAPT) operational prototype was deployed to Chicago in the summer of 2010, the first RAPT deployment outside of the New York departure airspace for which it was originally developed. The goal of the deployment was to evaluate the adaptability of RAPT's airspace definition, departure management...
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Overlapped digital subarray architecture for multiple beam phased array radar
April 11, 2011
Conference Paper
Published in:
EuCAP 2011, 5th European Conf. on Antrennas and Propagation, 11-15 April 2011, pp. 3027-3030.
Summary
MIT Lincoln Laboratory is conducting a technology demonstration of affordable Multifunction Phased Array Radar (MPAR) technology for Next Generation air traffic control and national weather surveillance services. Aggressive cost and performance goals have been established for the system. The array architecture and its realization using custom Transmit and Receive Integrated Circuits and panel-based Line Replaceable Unit (LRU) will be presented. A program plan for risk reduction and system demonstration will be outlined.
Summary
MIT Lincoln Laboratory is conducting a technology demonstration of affordable Multifunction Phased Array Radar (MPAR) technology for Next Generation air traffic control and national weather surveillance services. Aggressive cost and performance goals have been established for the system. The array architecture and its realization using custom Transmit and Receive Integrated...
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Partially-controlled Markov decision processes for collision avoidance systems
January 28, 2011
Conference Paper
Published in:
ICAART 2011, Proc. of the 2rd Int. Conf. on Agents and Artificial Intelligence, 28-30 January 2011, pp. 61-70.
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Deciding when and how to avoid collision in stochastic environments requires accounting for the likelihood and relative costs of future sequences of outcomes in response to different sequences of actions. Prior work has investigated formulating the problem as a Markov decision process, discretizing the state space, and solving for the optimal strategy using dynamic programming. Experiments have shown that such an approach can be very effective, but scaling to higher-dimensional problems can be challenging due to the exponential growth of the discrete state space. This paper presents an approach that can greatly reduce the complexity of computing the optimal strategy in problems where only some of the dimensions of the problem are controllable. The approach is demonstrated on an airborne collision avoidance problem where the system must recommend maneuvers to an imperfect pilot.
Summary
Deciding when and how to avoid collision in stochastic environments requires accounting for the likelihood and relative costs of future sequences of outcomes in response to different sequences of actions. Prior work has investigated formulating the problem as a Markov decision process, discretizing the state space, and solving for the...
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Use of a high-resolution deterministic weather forecast for strategic air traffic management decision support
January 14, 2011
Conference Paper
Published in:
91st American Meteorological Society Annual Meeting, 22-27 January 2011.
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One of the most significant air traffic challenges is managing the National Airspace System (NAS) in a manner that optimizes efficiency and mitigates avoidable delay, while maintaining safety, when convective weather is present. To do this, aviation planners seek to develop strategic air traffic management (ATM) plans and initiatives that anticipate weather constraints 2-8 hours in the future and identify options and alternatives for efficient operations during the off-nominal NAS conditions. In support of strategic planning, traffic managers currently conduct bi-hourly Strategic Planning Telcons (SPTs) and devise weather impact mitigations plans using the human-generated Collaborative Convective Forecast Product (CCFP). However, most operational decision-makers agree that the quasi-deterministic CCFP "polygons" (accompanied by a "low/high" forecast confidence rating) lack the granularity and temporal resolution to adequately support efficient strategic ATM plans and decisions. Moreover, traffic managers also assert that probabilistic forecasts of convective weather likelihood, while helpful in highlighting regions of possible airspace disruptions, generally lack the ability to resolve specific weather characteristics pertinent to strategic planning. MIT Lincoln Laboratory, NCAR Research Applications Laboratory, and NOAA Earth Systems Research Laboratory (ESRL) have collaborated to develop a high-resolution, rapidly updating 0-8 hour deterministic precipitation and echo tops forecast, known as CoSPA, to aid operational decision-makers in developing strategic plans for weather impact mitigation. In the summer of 2010, a comprehensive field study was conducted to assess potential benefits and the operational performance of CoSPA in the context of strategic ATM planning. The data were gathered by simultaneous real-time observations of I5 FAA and airline operations facilities during 15 convective weather impact days affecting the Northern Plains, Great Lakes, and East Coast regions of the NAS. CoSPA field evaluation results will be presented to demonstrate the various ways aviation planners have utilized the increased spatial and temporal resolution of CoSPA - the ability of CoSPA to resolve storm structure and refine forecasts with high update rates - to make more detailed assessments of potential weather impacts and to determine the subsequent need for airspace management initiatives. Results will also be presented that highlight CoSPA enhancement needs, primarily related to forecast uncertainty, that would improve the operational effectiveness of CoSPA-derived weather impact mitigation plans. Finally, opportunities to translate CoSPA deterministic forecasts into integrated weather-ATM decision support for specific strategic planning tasks will be discussed
Summary
One of the most significant air traffic challenges is managing the National Airspace System (NAS) in a manner that optimizes efficiency and mitigates avoidable delay, while maintaining safety, when convective weather is present. To do this, aviation planners seek to develop strategic air traffic management (ATM) plans and initiatives that...
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Field & (data) stream: a method for functional evolution of the Air Traffic Management Route Availability Planning Tool (RAPT)
September 27, 2010
Conference Paper
Published in:
HFES 2010, Proc. of the 54th Human Factors and Ergonomics Society Annual Mtg., 27 September 2010, pp. 104-108.
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A method coupling field evaluation with operations data analysis is presented as an effective means to functionally evolve a decision support system. The case study used to illustrate this method is the evaluation of the Route Availability Planning Tool (RAPT), a decision support tool to improve departure efficiency in convective weather in New York air traffic facilities. It was only through a combination of quantitative performance data analysis and field observations to identify key elements of the decision making process that the designers were able to determine the most critical departure management decision requiring support, leading to significant improvements in departure efficiency.
Summary
A method coupling field evaluation with operations data analysis is presented as an effective means to functionally evolve a decision support system. The case study used to illustrate this method is the evaluation of the Route Availability Planning Tool (RAPT), a decision support tool to improve departure efficiency in convective...
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On estimating mid-air collision risk
September 13, 2010
Conference Paper
Published in:
ATIO 2010: 10th AIAA Aviation Technology Integration and Operations Conf., 13-15 September 2010.
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Many aviation safety studies involve estimating near mid-air collision (NMAC) rate. In the past, it has been assumed that the probability that an NMAC leads to a mid-air collision is 0.1, but there has not yet been a comprehensive study to serve as a basis for this estimate. This paper explains how to use existing encounter models, a flight simulation framework, three-dimensional aircraft wireframe models, and surveillance data to estimate mid-air collision risk. The results show that 0.1 is an overly conservative estimate and that the true rate is likely to be an order of magnitude lower.
Summary
Many aviation safety studies involve estimating near mid-air collision (NMAC) rate. In the past, it has been assumed that the probability that an NMAC leads to a mid-air collision is 0.1, but there has not yet been a comprehensive study to serve as a basis for this estimate. This paper...
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Assessment and interpretation of en route Weather Avoidance Fields from the Convective Weather Avoidance Model
September 13, 2010
Conference Paper
Published in:
ATIO 2010: 10th AIAA Aviation Technology Integration and Operations Conf., 13-15 September 2010.
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This paper presents the results of a study to quantify the performance of Weather Avoidance Fields in predicting the operational impact of convective weather on en route airspace. The Convective Weather Avoidance Model identifies regions of convective weather that pilots are likely to avoid based upon an examination of the planned and actual flight trajectories in regions of weather impact. From this model and a forecast of convective weather from the Corridor Integrated Weather System a probabilistic Weather Avoidance Field can be provided to automated decision support systems of the future impact of weather on the air traffic control system. This paper will present three alternative spatial filters for the Convective Weather Avoidance Model, quantify their performance, address deficiencies in performance, and suggest potential improvements by looking at the ATC environment and common situational awareness between the cockpit and air traffic control.
Summary
This paper presents the results of a study to quantify the performance of Weather Avoidance Fields in predicting the operational impact of convective weather on en route airspace. The Convective Weather Avoidance Model identifies regions of convective weather that pilots are likely to avoid based upon an examination of the...
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