Publications
Wind prediction accuracy for air traffic management decision support tools
June 13, 2000
Conference Paper
Published in:
Proc. 3rd Int. Air Traffic Management R&R Seminar, 13-16 June 2000, pp. 1-9.
Summary
Air traffic automation depends on accurate trajectory predictions. Flight tests show that wind errors are a large source of error. Wind-field accuracy is sufficient on average, but large errors occasionally exist that cause significant errors in trajectory-prediction. A year long study was conducted to better understand the wind-prediction errors, to establish metrics for quantifying large errors, and to validate two approaches to improve wind prediction accuracy. Three methods are discussed for quantifying large errors: percentage of point errors that exceed 10 m/s, probability distribution of point errors, and the number of hourly time periods with a high number of large errors. The baseline wind-prediction system evaluated for this study is the Rapid Update Cycle (RUC). Two approaches to improving the original RUC wind predictions are examined. The first approach is to enhance RUC in terms of increased model resolution, enhancement of the model physics, and increased observational input data. The second method is to augment the RUC output, in near-real time, through an optimal-interpolation scheme that incorporates the latest aircraft reports received since the last RUC update. Both approaches are shown to greatly reduce the occurrence of large wind errors.
Summary
Air traffic automation depends on accurate trajectory predictions. Flight tests show that wind errors are a large source of error. Wind-field accuracy is sufficient on average, but large errors occasionally exist that cause significant errors in trajectory-prediction. A year long study was conducted to better understand the wind-prediction errors, to...
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Weather radar development and application programs
June 1, 2000
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 12, No. 2, 2000, pp. 367-382.
Summary
Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena by radar is challenging because it requires rapid and accurate analysis of the three-dimensional storm structure in the presence of intense ground-clutter returns. For the last two decades, Lincoln Laboratory has been tackling this challenge by applying advanced radar signal- and image-processing techniques to weather radar data. The resulting technology is being deployed in radar-based weather information systems at major airports throughout the United States. We first discuss the salient meteorological factors that contribute to the formation of microburst wind shear, then we provide some general background on the use of pulse-Doppler radar for weather detection. We describe two specific Lincoln Laboratory programs that have generated deployed systems: the Terminal Doppler Weather Radar (TDWR) and the ASR-9 Weather Systems Processor (WSP). The article concludes with a discussion of future detection strategies that emphasizes the fusion of weather radar data by the Integrated Terminal Weather System (ITWS).
Summary
Weather phenomena such as microburst wind shear and severe thunderstorms are major concerns to the aviation industry. A number of significant airplane accidents have resulted from wind-shear encounters during takeoff and landing, and thunderstorms are a major contributor to airplane delay. Providing fully automated and timely warnings of these phenomena...
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The design and validation of the ITWS synthetic sensor data generator
April 12, 2000
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-289
Summary
The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS have been conducted over a multi-year period at several major airports (Memphis, TN, Orlando, FL, Dallas, TX, and New York, NY). Although there are many meteorological events observed at these four airports, the experimental test data sets obtained will not fully suffice for ITWS qualification testing because of limitations in the severity of the weather events and because of the sensor configurations available at these locations. This report describes the design and validation of the Synthetic Data Generator (SDG), which is a tool to provide a production ITWS system with meteorologically consistent scenarios and full ITWS sensor configurations that will create maximal computational loads that can be expected when the system is deployed. Also, the SDG will be a tool for ongoing ITWS maintenance and support. As such, the SDG will complement the extensive experimental data sets collected at the four ITWS demonstration sites. The SDG is designed to specify parameters for a collection of meteorological models describing the various weather phenomena, their motion, appearance, and growth/decay. The software creates several three-dimensional (3D) grids of reflectivity and velocity at each time-step. Finally, the SDG generates sensor (i.e., TDWR, NEXRAD, ASR-9) data by applying the model for each specific sensor's measurements to the 3D grids. The validation of the meteorological model and the sensor model data have been accomplished using a display tool and by assessing results numerically.
Summary
The Integrated Terminal Weather System (ITWS) is an aviation safety and air traffic management decision support system that acquires data from various FAA and NWS sensors and generates a number of products for dissemination to FAA facilities managing air traffic in the terminal area. The development and demonstrations of ITWS...
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Lincoln Laboratory Evaluation of TCAS II Logic Version 7 Appendices Volume II
December 13, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-268,II
Summary
Volume I described the analysis procedures and inputs. This volume presents tables and figures that were generated during the assessment to the TCAS Logic Performance.
Summary
Volume I described the analysis procedures and inputs. This volume presents tables and figures that were generated during the assessment to the TCAS Logic Performance.
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Lincoln Laboratory Evaluation of TCAS II Logic Version 7 Volume I
December 13, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-268,I
Summary
This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in the U.S. airspace. Version 7 is a major revision to the TCAS II logic consisting of more than 300 separately defined changes affecting all majot TCAS areas (surveillance, CAS logic and displays/aurals). Lincoln Laboratory Evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual tracks recorded in U.S. airspace. The main goals of the evaluation were: (1) to study the performance of the new TCAS-TCAS coordinated reversal logic; (2) to detect and explain any areas of performance; (3) to examine the performance of the version 7 logic for the 30 Representative NMACs identified during the 6.04a logic evaluation; and (4) to understand the limitations of the logic by analyzing every version NMAC. Five Lincoln Laboratory analysis programs written for previous logic evaluation work were updated and new software was written to aid in the evaluation of TCAS-TCAS sense reversals. There were four phases of the evaluation corresponding to the above goals. For each phase the report gives an overview of the evaluation approach taken and a description of the results. An overall summary and perspective on the evolution of the TCAS II logic are given at the end of the report.
Summary
This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...
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Weather sensing and data fusion to improve safety and reduce delays at major west coast airports
November 30, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-290
Summary
The objective of this study was to analyze the weather sensing and data fusion required to improve safety and reduce delays at a number of west coast airports that are not currently scheduled to receive an Integrated Terminal Weather System (ITWS). This report considers the Los Angeles (LAX), San Francisco (SFO), Seattle (SEA) and Portland, OR (PDX) international airports. A number of visits were made to the various ATC facilities to better understand their weather decision support operational needs. Analyses were made of an incident of lightning strikes to two aircraft at SEA in February 1999, and a prototype terminal winds product was developed for LAX that uses profilers as well as plane reports to update the the National Weather Service (NWS) Rapid Update Cycle (RUC) winds estimates. We found that an augmented ITWS could potentially address safety concerns for triggered lightning strikes and vertical wind shear in winter storms at Portland and Seattle. An augmented ITWS terminal winds product (that uses wind profiler data in addition to the current ITWS sensors) could provide very large delay reductions for LAX and SFO during winter storms as a component of a wake vortex advisory system. This augmented product also could provide significant delay reduction benefits at SEA. The sensors required to obtain the projected benefits at SFO do not exist currently. Portland may warrant additional sensors to address the vertical wind shear problems, and LAX would require additional sensors for a wake vortex advisory system. We recommend near-term experimental measurements at PDX to determine the optimum sensor mix and that an operational evaluation of the prototype augmented ITWS terminal winds product be carried out at LAX to determine if the current sensor mix can meet operational needs. Lightning strike data at SEA and PDX should be analyzed to determine if a proposed triggered lightning predictant is accurate.
Summary
The objective of this study was to analyze the weather sensing and data fusion required to improve safety and reduce delays at a number of west coast airports that are not currently scheduled to receive an Integrated Terminal Weather System (ITWS). This report considers the Los Angeles (LAX), San Francisco...
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A comparative study of existing and proposed FAA and Eurocontrol CHIs for en route air traffic control
September 26, 1999
Conference Paper
Published in:
44th Annual Air Traffic Control Association Conf. Proc., 26-30 September 1999, pp. 22-26.
Summary
In this paper we present a comparison of the Computer Human Interface (CHI) similarities and differences among the key Free Flight Phase 1 (FFP1) products for en route air traffic control (ATC) and air traffic control management (ATM) as well as some recent Eurocontrol-based CHI innovations. Our comparative study focuses on details of these disparate CHIs and the potential introduction of advanced graphical interactive features seen in the Eurocontrol CHI. Active US controllers who participated in Eurocontrol's Operational Display and Input Development (ODID) study have requested that the FAA develop an alternative CHI based on ODID and its successors such as the Denmark Sweden Interface (DSI). MIT Lincoln Laboratory has built a CHI Requirements Engineering Model (CREM) to support testing of an alternative ODID-like CHI that is feasible given the newly deployed Display System Replacement (DSR).
Summary
In this paper we present a comparison of the Computer Human Interface (CHI) similarities and differences among the key Free Flight Phase 1 (FFP1) products for en route air traffic control (ATC) and air traffic control management (ATM) as well as some recent Eurocontrol-based CHI innovations. Our comparative study focuses...
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An evaluation of the ASR-9 weather channel based on observations from the ITWS prototypes
September 23, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-270
Summary
The Federal Aviation Administration's (FAA) Airport Surveillance Radar (ASR-9) is a high-scan-rate system which provides a "critical" function in terms of air traffic control (ATC). In addition to its primary role of air traffic surveillance, the system also generates precipitation data for display on air traffic specialists' radar scopes and for use by automated systems such as the Integrated Terminal Weather System (ITWS) and Weather Systems Processor (WSP). Air traffic managers use these data to provide optimum routes for aircraft operating in and near the Terminal Radar Approach Control (TRACON) airspace. The primary advantage of the ASR-9 - as an aviation weather radar - over either the Terminal Doppler Weather Radar (TDWR) or the Next Generation Weather Radar (NEXRAD) is the rapid update rate, i.e., 30 seconds, which provides air traffic managers with a more accurate representation of weather echo location within the sensor's domain. This is far superior toeither the TDWR or NEXRAD, which takes from 2.5 to 6 minutes to create a volume scan, depending on the scan strategy. The sensor is also quite reliable, with limited down time. An analysis of ASR-9 data from the ITWS prototypes has uncovered a number of problems, which impact the quality of the precipitation data. The data quality issues discussed are overly aggressive ground clutter suppression, polarization mode issues, hardware failures associated with high beandlow beam switching, attenuatiodsignal depolarization, beam-filling losses, bright- band contamination, distant weather contamination, calibration issues, and radadantenna failures. The recommendations to address the ASR-9 data quality issues can be grouped into three categories: "Variable Site Parameter (VSP)" adjustments, hardware component maintenance checks, and automated flagging of data quality problems. The report includes discussion of the frequency and characteristics of each degradation, presenting both hardware and non- hardware related problems, and concludes with proposed solutions to the problems and recommendations designed to improve the overall utility of the ASR-9 precipitation data.
Summary
The Federal Aviation Administration's (FAA) Airport Surveillance Radar (ASR-9) is a high-scan-rate system which provides a "critical" function in terms of air traffic control (ATC). In addition to its primary role of air traffic surveillance, the system also generates precipitation data for display on air traffic specialists' radar scopes and...
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Operational and spectrum tests for ATIDS at Dallas/Fort Worth Airport
September 20, 1999
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-272
Summary
Runway Incursion (RI) prevention is on the National Transportation Safety Board's (NTSB) list of "10 Most Wanted" safety improvements. Improved surveillance on the airport surface is an important ingredient in that it improves situational awareness and improves the accuracy of tracks used by automation algorithms. Towards this goal, the Runway Incursion Reduction Program (RIRP) has been developing the Airport Target Identification System (ATIDS). ATIDS is a prototype multilateration and Automatic Dependent Surveillance - Broadcast (ADS-B) system. It requires the enabling of existing transponders on the airport surface....The RIRP team, which includes the FAA Volpe National Transportation Systems Center, Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL) and Trios Associates, Inc., has conducted interferences tests at Dallas/Fort Worth Airport (DFW) to quantify the impact that ATIDS would have on that high-use environment. The tests included environmental 1040/1090 MHz measurements, ATCRBS false target investigations, and Mode S interrogation tests. This document reports the results of these tests. [Not complete].
Summary
Runway Incursion (RI) prevention is on the National Transportation Safety Board's (NTSB) list of "10 Most Wanted" safety improvements. Improved surveillance on the airport surface is an important ingredient in that it improves situational awareness and improves the accuracy of tracks used by automation algorithms. Towards this goal, the Runway...
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Criteria for sprites and elves based on Schumann resonance observations
July 27, 1999
Journal Article
Published in:
J. Geophys. Res., Vol. 104, No. D14, 27 July 1999, pp. 16,943-16,964.
Summary
Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the measured time constants for lightning charge transfer with the electrostatic relaxation time at altitudes of nighttime sprite initiation (50-70 km) generally validate the electrostatic assumption in predictions made initially by Wilson [1925]. The measured charge moments (Q dS = 200-2000 C-km) are large in comparison with ordinary negative lightning but are generally insufficient to account for conventional air breakdown at sprite altitudes. The measured charge moments, however, are sufficient to account for electron runaway breakdown, and the long avalanche length in this mechanism also accounts for the exclusive association of sprites with ground flashes of positive polarity. The association of elves with large peak currents (50-200 kA) measured by the National Lightning Detection Network in a band pass beyond the Schumann resonance range is consistent with an electromagnetic pulse mechanism for these events.
Summary
Ground flashes with positive polarity associated with both sprites and elves excite the Earth's Schumann resonances to amplitudes several times greater than the background resonances. Theoretical predictions for dielectric breakdown in the mesosphere are tested using ELF methods to evaluate vertical charge moments of positive ground flashes. Comparisons of the...
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