Publications
A comprehensive aircraft encounter model of the National Airspace System
December 1, 2008
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 17, No. 2, December 2008, pp. 41-54.
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Summary
Collision avoidance systems play an important role in the future of aviation safety. Before new technologies on board manned or unmanned aircraft are deployed, rigorous analysis using encounter simulations is required to prove system robustness. These simulations rely on models that accurately reflect the geometries and dynamics of aircraft encounters at close range. These types of encounter models have been developed by several organizations since the early 1980s. Lincoln Laboratory's newer encounter models, however, provide a higher-fidelity representation of encounters, are based on substantially more radar data, leverage a theoretical framework for finding optimal model structures, and reflect recent changes in the airspace.
Summary
Collision avoidance systems play an important role in the future of aviation safety. Before new technologies on board manned or unmanned aircraft are deployed, rigorous analysis using encounter simulations is required to prove system robustness. These simulations rely on models that accurately reflect the geometries and dynamics of aircraft encounters...
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Automatic dependent surveillance-broadcast in the Gulf of Mexico
December 1, 2008
Journal Article
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Lincoln Laboratory Journal, Vol. 17, No. 2, December 2008, pp. 55-69.
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The Federal Aviation Administration is adopting Automatic Dependent Surveillance-Broadcast (ADS-B) to provide surveillance in the National Airspace System (NAS). Aircraft separation services are currently provided by a system of en route and terminal radars, and the performance of these radars in part dictates the separation distance required between aircraft. ADS-B is designed to provide comparable service in areas where no radar coverage exists. It will eventually be the primary surveillance source in the NAS, if it is proven to provide performance equal to or better than radar.
Summary
The Federal Aviation Administration is adopting Automatic Dependent Surveillance-Broadcast (ADS-B) to provide surveillance in the National Airspace System (NAS). Aircraft separation services are currently provided by a system of en route and terminal radars, and the performance of these radars in part dictates the separation distance required between aircraft. ADS-B...
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Uncorrelated encounter model of the National Airspace System version 1.0
November 14, 2008
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-345
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Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are flying under Visual Flight Rules (VFR) and which may not be in contact with air traffic control. In response to the need to develop a model of these types of encounters, Lincoln Laboratory undertook an extensive radar data collection and modeling effort involving more than 120 sensors across the U.S. This report describes the structure and content of that encounter model. The model is based on the use of Bayesian networks to represent relationships between dynamic variables and to construct random aircraft trajectories that are statistically similar to those observed in the radar data. The result is a framework from which representative intruder trajectories can be generated and used in fast-time Monte Carlo simulations to provide accurate estimates of collision risk. The model described in this report is one of three developed by Lincoln Laboratory. An encounter with an intruder that does not have a transponder, or between two aircraft using a Mode A code of 1200 (VFR), is uncorrelated in the sense that it is unlikely that there would be prior intervention by air traffic control. The uncorrelated model described in this report is based on transponder-equipped aircraft using a 1200 (VFR) Mode A code observed by radars across the U.S. As determined from a comparison against primary-only tracks, in addition to representing VFR-on-VFR encounters, this model is representative of encounters between a cooperative aircraft and conventional noncooperative aircraft similar to those that use a 1200 transponder code. A second uncorrelated model is also being developed for unconventional aircraft that have different flight characteristics than 1200-code aircraft. Finally, a correlated encounter model has been developed to represent situations in which it is likely that there would be air traffic control intervention prior to a close encounter. The correlated model applies to intruders that are using a discrete (non-1200) code. Separate electronic files are available from Lincoln Laboratory that contain the statistical data required to generate and validate encounter trajectories. Details on how to interpret the data file and an example of how to randomly construct trajectories are provided in Appendices A and B, respectively. A Matlab software package is also available to generate random encounter trajectories based on the data tables. A byproduct of the encounter modeling effort was the development of National aircraft track and traffic density databases. Example plots of traffic density data are provided in this report, but the complete track and density databases are not provided in electronic form due to their size and the complexity of processing specific locations, altitudes, and times.
Summary
Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are...
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Correlated encounter model for cooperative aircraft in the National Airspace System, version 1.0
October 24, 2008
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-344
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Summary
This document describes a new cooperative aircraft encounter model for the National Airspace System (NAS). The model is used to generate random close encounters between transponder-equipped (cooperative) aircraft in fast-time Monte Carlo simulations to evaluate collision avoidance system concepts. An extensive set of radar data from across the United States, including more than 120 sensors and collected over a period of nine months, was used to build the statistical relationships in the model to ensure that the encounters that are generated are representative of actual events in the airspace.
Summary
This document describes a new cooperative aircraft encounter model for the National Airspace System (NAS). The model is used to generate random close encounters between transponder-equipped (cooperative) aircraft in fast-time Monte Carlo simulations to evaluate collision avoidance system concepts. An extensive set of radar data from across the United States...
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Operational usage of the Route Availability Planning Tool during the 2007 convective weather season : executive summary
October 6, 2008
Project Report
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MIT Lincoln Laboratory Report ATC-339-1
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The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance at forecasting route blockage, to assess RAPT operational use during adverse weather, and to evaluate RAPT benefits. The operational test found that RAPT guidance was operationally sound and timely in many circumstances. RAPT applications included increased departure route throughput, more efficient reroute planning, and more timely decision coordination. Estimated annual NY departure delay savings attributed to RAPT in 2007 totaled 2,300 hours, with a cost savings of $7.5 M. The RAPT field study also sought to develop a better understanding of NY traffic flow decision-making during convective weather impacts since the RAPT benefi ts in 2007 were significantly limited by a number of factors other than direct weather impacts. Observations were made of the multi-facility departure management decision chain, the traffic management concerns and responsibilities at specific FAA facilities, and the procedures and pitfalls of the current process for capturing and disseminating key information such as route/fix availability and restrictions.
Summary
The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance...
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Operational usage of the Route Availability Planning Tool during the 2007 convective weather season
October 6, 2008
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-339
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Summary
The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance at forecasting route blockage, to assess RAPT operational use during adverse weather, and to evaluate RAPT benefits. The operational test found that RAPT guidance was operationally sound and timely in many circumstances. RAPT applications included increased departure route throughput, more efficient reroute planning, and more timely decision coordination. Estimated annual NY departure delay savings attributed to RAPT in 2007 totaled 2,300 hours, with a cost savings of $7.5 M. The RAPT field study also sought to develop a better understanding of NY traffic flow decision-making during convective weather impacts since the RAPT benefits in 2007 were significantly limited by a number of factors other than direct weather impacts. Observations were made of the multi-facility departure management decision chain, the traffic management concerns and responsibilities at specific FAA facilities, and the procedures and pitfalls of the current process for capturing and disseminating key information such as route/fix availability and restrictions.
Summary
The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance...
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Detection probability modeling for airport wind-shear sensors
September 15, 2008
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-340
Summary
An objective wind-shear detection probability estimation model is developed for radar, lidar, and sensor combinations. The model includes effects of system sensitivity, site-specific wind-shear, clutter, and terrain blockage characteristics, range-aliased obscuration statistics, antenna beam filling and attenuation, and signal processing differences which allow a sensor- and site-specific performance analysis of deployed and future systems. A total of 161 sites are analyzed for the study, consisting of airports currently serviced by the Terminal Doppler Weather Radar (TDWR) (46), Airport Surveillance Radar Weather Systems Processor (ASR-9 WSP) (35), Low Altitude Wind Shear Alert System-Relocation/Sustainment (LLWAS-RS) (40), and no wind-shear detection system (40). Sensors considered are the TDWR, WSP, LLWAS, Weather Surveillance Radar 1988-Doppler (WSR-88D, commonly known as NEXRAD), adn the Lockheed Martin Coherent Technologies (LMCT) Doppler lidar and proposed x-band radar. [not complete]
Summary
An objective wind-shear detection probability estimation model is developed for radar, lidar, and sensor combinations. The model includes effects of system sensitivity, site-specific wind-shear, clutter, and terrain blockage characteristics, range-aliased obscuration statistics, antenna beam filling and attenuation, and signal processing differences which allow a sensor- and site-specific performance analysis of...
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Convection diagnosis and nowcasting for oceanic aviation applications
August 25, 2008
Conference Paper
Published in:
Proc. SPIE, Vol. 7088, Remote Sensing Applications for Aviation Weather Hazard Detection and Decision Support, 25 August 2008, 708808.
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An oceanic convection diagnosis and nowcasting system is described whose domain of interest is the region between the southern continental United States and the northern extent of South America. In this system, geostationary satellite imagery are used to define the locations of deep convective clouds through the weighted combination of three independent algorithms. The resultant output, called the Convective Diagnosis Oceanic (CDO) product, is independently validated against space-borne radar and lightning products from the Tropical Rainfall Measuring Mission (TRMM) satellite to ascertain the ability of the CDO to discriminate hazardous convection. The CDO performed well in this preliminary investigation with some limitations noted. Short-term, 1-hr and 2-hr nowcasts of convection location are performed within the Convective Nowcasting Oceanic (CNO) system using a storm tracker. The CNO was found to have good statistical performance at extrapolating existing storm positions. Current work includes the development and implementation of additional atmospheric features for nowcasting convection initiation and to improve nowcasting of mature convection evolution.
Summary
An oceanic convection diagnosis and nowcasting system is described whose domain of interest is the region between the southern continental United States and the northern extent of South America. In this system, geostationary satellite imagery are used to define the locations of deep convective clouds through the weighted combination of...
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A Bayesian approach to aircraft encounter modeling
August 18, 2008
Conference Paper
Published in:
AIAA Guidance, Navigation, and Control Conf., 18-21 August 2008.
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Aircraft encounter models can be used in a variety of analyses, including collision avoidance system safety assessment, sensor design trade studies, and visual acquisition analysis. This paper presents an approach to airspace encounter model construction based on Markov models estimated from radar data. We use Bayesian networks to represent the distribution over initial states and dynamic Bayesian networks to represent transition probabilities. We apply Bayesian statistical techniques to identify the relationships between the variables in the model to best leverage a large volume of raw aircraft track data obtained from more than 130 radars across the United States.
Summary
Aircraft encounter models can be used in a variety of analyses, including collision avoidance system safety assessment, sensor design trade studies, and visual acquisition analysis. This paper presents an approach to airspace encounter model construction based on Markov models estimated from radar data. We use Bayesian networks to represent the...
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Applications of a macroscopic model for en route sector capacity
August 18, 2008
Conference Paper
Published in:
AIAA Guidance, Navigation and Control Conf. and Exhibit, 18-21 August 2008.
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Airspace capacity estimates are important both for airspace design and for operational air traffic management. Considerable effort has gone into understanding the complexity factors that reduce sector capacity by increasing controller workload. Yet no analytical means is available for accurately estimating the maximum capacity of an en route sector. The Monitor Alert Parameter (MAP) values that determine the operational traffic limit of en route sectors in the United States account only for workload from inter-sector coordination tasks. We propose a more complete sector capacity model that also accounts for workload from conflict avoidance and recurring tasks. We use mean closing speeds and airspace separation standards to estimate aircraft conflict rates. We estimate the mean controller service times for all three task types by fitting the model against observed peak traffic counts for hundreds of en route airspace volumes in the Northeastern United States. This macroscopic approach provides numerical capacity predictions that closely bound peak observed traffic densities for those airspace volumes. This paper reviews recent efforts to improve the accuracy of the bound by replacing certain global parameters with measured data from individual sectors. It also compares the model capacity with MAP values for sectors in the New York Center. It concludes by illustrating the use of the model to predict the capacity benefits of proposed technological and operational improvements to the air traffic management system.
Summary
Airspace capacity estimates are important both for airspace design and for operational air traffic management. Considerable effort has gone into understanding the complexity factors that reduce sector capacity by increasing controller workload. Yet no analytical means is available for accurately estimating the maximum capacity of an en route sector. The...
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