Publications
Quantifying airport terminal area weather surveillance requirements
May 24, 1993
Conference Paper
Published in:
26th Int. Conf. on Radar Meteorology, 24-28 May 1993, pp. 47-49.
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Summary
The Federal Aviation Administration (FAA) Terminal Area Surveillance System (TASS) research, engineering, and development program was initiated in part to address future weather sensing needs in the terminal area. By the early 21st century, planned systems such as the Terminal Doppler Weather Radar (TDWR) and Airport Surveillance Radar-9 (ASR-9) will be well into their designed life cycles. Any new terminal weather surveillance system should be designed to address existing deficiencies. Key unmet weather sensing needs include detections of: true 3-dimensional winds (vs. radial component), winds in the absence of precipitation, wake vortices, total lightning, hail, icing conditions, clear air turbulence, hazardous weather cells (with adequate time and space resolution), cloud cover and cloud bases (including layers), fog, and visibility (Runway Visual Range), as well as predictions of: the atmospheric conditions mentioned above, wind shifts, microbursts, tornadoes, and snow/rainfall rates (Evans 1991a, McCarthy 1991). In this paper, we investigate the premise that hazardous weather cells are not currently being measured with adequate time and space resolution in the terminal area. Since a new surveillance system should be based on knowledge of storm dynamics, we have performed a preliminary study of update rate (using rapid scan radar to detect rapidly developing thunderstorms and precursors to the low altitude hazards such as microbursts that they produce. Other aspects of a future radar system such as multi-parameter techniques required to discriminate between ice and water phase precipitation, etc. are not considered.
Summary
The Federal Aviation Administration (FAA) Terminal Area Surveillance System (TASS) research, engineering, and development program was initiated in part to address future weather sensing needs in the terminal area. By the early 21st century, planned systems such as the Terminal Doppler Weather Radar (TDWR) and Airport Surveillance Radar-9 (ASR-9) will...
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Preliminary results of the weather testing component of the Terminal Doppler Weather Radar operational test and evaluation
May 24, 1993
Conference Paper
Published in:
Proc. 26th Int. Conf. on Radar Meteorology, 24-28 May 1993, pp. 29-34.
Summary
The Terminal Doppler Weather Radar (TDWR) system which has been developed by Raytheon Co. for the Federal Aviation Administration (FAA), provides automatic detection of microbursts and low-altitude wind shear. Microburst- and gust front-induced wind shear can result in a sudden, large change in airspeed which can have disastrous effect on aircraft performance. during take off or landing. The second major function of TDWR is to improve air traffic management through forecasts of wind shifts, precipitation and other weather hazards. The TDWR system generates Doppler velocity, reflectivity, and spectrum width data. The base data are automatically dealiased and clutter is removed through filtering and mapping. Precipitation and windshear products, such as microbursts and gust fronts, are displayed as graphic products on the Geographic Situation Display which is intended for use by Air Traffic Control supervisors. Alphanumeric messages indicating the various windshear alerts and derived airspeed losses and gains are sent to a flat panel ribbon display which is used by the controllers in the control tower. The TDWR proof-of-concept and operational feasibility have been demonstrated in a number of FAA-sponsored tests and evaluations conducted by Massachusetts Institute of Technology's Lincoln Laboratory (MIT/LL) in Memphis, TN (1985); Huntsville, AL (1986); Denver, CO (1987, 1988); Kansas City, MO (1989, and Orlando, FL (1990-1992). In order to verify that the TDWR meets FAA operational suitability and effectiveness requirements, an Operational Test & Evaluations (OT&E) was conducted at the Oklahoma City site during the period from 24 August to 30 October 1992. The testing addressed National Airspace System (NAS)-SS-1000 requirements, weather detection performance, safety, operational system performance, maintenance, instruction books, Remote Maintenance Monitoring System (RMMS), system adaptable parameters, bullgear wear, and limited Air Traffic (AT) suitability. The TDWR OT&E Integration and Operational testing was conducted using a variety of methods dependent on the area being tested. This paper discusses primarily the weather detection performance testing. A rough analysis was performed on the algorithm output and the base data to determine the performance of the TDWR in detecting wind shear phenomena. Final results will be available after additional testing, which is scheduled for Spring of 1993, and post analysis in conducted.
Summary
The Terminal Doppler Weather Radar (TDWR) system which has been developed by Raytheon Co. for the Federal Aviation Administration (FAA), provides automatic detection of microbursts and low-altitude wind shear. Microburst- and gust front-induced wind shear can result in a sudden, large change in airspeed which can have disastrous effect on...
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Real-time multiple single Doppler analysis with NEXRAD data
May 24, 1993
Conference Paper
Published in:
26th Int. Conf. on Radar Meteorology, 24-28 May 1993, pp. 460-462.
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Summary
As part of the Aviation Weather Development Program of the Federal Aviation Administration, a high resolution winds analysis system was demonstrated at Orlando International Airport (MCO) in the summer of 1992. The purpose of this demonstration was to illustrate the winds analysis capability possible from operational sensors in the mid '90s. An important part of the design of this system was the development of a procedure for the assimilation of Doppler data from multiple radars. This procedure had to be able to automatically handle regions with missing data from one or more radars, as well as avoid baseline instability. The two operational radars scanning the analysis region were the National Weather Service WSR-88D (NEXRAD) radar located approximately 65 km east and slightly south of MCO, and the MIT prototype Terminal Doppler Weather Radar (TDWR) located 7 km due south of the airport. The base data from these two Doppler radars were the major information component for the analysis system. Our system includes the most recent improvements in the winds analysis portion of the Local Analysis and Prediction System (LAPS) developed by the Forecast Systems Laboratory (McGinely et al., 1991). LAPS is designed to run locally on systems affordable for operational weather offices and takes advantages of all sources of local data at the highest possible resolution. Our implementation for the airport terminal region id called the Terminal-area LAPS (T-LAPS). LAPS formerly had a technique for the assimilation of data from a single Doppler radar. We have modified that technique for the assimilation of data from the two available radars. Our approach, using a Multiple Single Doppler Analysis (MSDA) technique, is more suited for unsupervised operational analysis than traditional Dual Doppler Analysis (DDA), because it is able to handle such problems as incomplete data and baseline instability. We will describe the T-LAPS analysis, with particular attention to our implementation of ASDA, and give some examples from our demonstration.
Summary
As part of the Aviation Weather Development Program of the Federal Aviation Administration, a high resolution winds analysis system was demonstrated at Orlando International Airport (MCO) in the summer of 1992. The purpose of this demonstration was to illustrate the winds analysis capability possible from operational sensors in the mid...
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Optimal mean velocity estimation for Doppler weather radars
May 1, 1993
Journal Article
Published in:
IEEE Trans. Geosci. Remote Sens., Vol. 31, No. 3, May 1993, pp. 575-586.
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Summary
Optimal Doppler velocity estimation is explored for a standard Gaussian signal measurement model and thematic maximum likelihood (ML) and Bayes estimation. Because the model considered depends on a vector parameter (velocity, spectrum width (SW), and signal-to-noise ratio (SNR), the exact formulation of an ML or Bayes solution involves a system of coupled equations which cannot be made explicit for any of the parameters. In the past, iterative methods have been suggested for solving the required equations. In addition to being computationally intensive, it is unclear whether an iterative method can be constructed to converge well under general conditions. Simple computational forms are shown to exist when SW and SNR are assumed known. An information theoretic concept is used to propose an adaptive extension of these equations to the general case of SW and SNR unknown. This new idea is developed to the poise of operational application. A Monte Carlo simulations experiment is used to verify that the method can work; the example presented considers the particularly difficult situation of no a priori information for either SW or SNR under the additional constraint of a very small (20 pulse samples) sample size. The improved performance of this new Doppler velocity estimator is documented by comparison with derived optimal bounds and with the performance of the well-known pulse pair (PP) method. Small-sample estimator statistics are presented; and Bayes estimator results, assuming known SW and SNR, are used to provide true performance bounds for comparison. Cramer-Rao (CR) bounds are also derived and shown to be inferior to the Bayes bounds in the small sample case considered.
Summary
Optimal Doppler velocity estimation is explored for a standard Gaussian signal measurement model and thematic maximum likelihood (ML) and Bayes estimation. Because the model considered depends on a vector parameter (velocity, spectrum width (SW), and signal-to-noise ratio (SNR), the exact formulation of an ML or Bayes solution involves a system...
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Automated gust front detection using knowledge-based signal processing
April 20, 1993
Conference Paper
Published in:
Proc. 1993 IEEE Natl. Radar Conf., 20-22 April 1993, pp. 150-155.
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Summary
For reasons of aviation safety and airport operations efficiency, gust front detection and tracking is an important product of Doppler weather radars developed for use in airport terminal areas. Previous gust front algorithms, which have relied on the detection of one or two conspicuous signatures in Doppler radar imagery, have worked reasonably well in images generated by the high-resolution, pencil-beam Terminal Doppler Weather Radar (TDWR). The latest Airport Surveillance Radar, enhanced with a Wind Shear Processor (ASR-9 WSP), is being developed as a less expensive alternative weather radar. Although gust fronts are visible to human observers in ASR-9 WSP imagery, the lower sensitivity and less reliable Doppler measurements of this radar make automated gust front detection a much more challenging problem. Using machine intelligence and knowledge-based signal processing techniques developed in the context of automatic target recognition, a Machine Intelligent Gust Front Algorithm (MIGFA) has been constructed that is radically different from the previous algorithms. Developed initially for use with ASR-9 WSP data, MIGFA substantially outperforms a state-of-the-art gust front detection algorithm based on earlier approaches. These results also indirectly suggest that MIGFA performance may be nearly as good as human performance. Preliminary results of an operational test period (two months, approximately 15000 scans processed) are presented.
Summary
For reasons of aviation safety and airport operations efficiency, gust front detection and tracking is an important product of Doppler weather radars developed for use in airport terminal areas. Previous gust front algorithms, which have relied on the detection of one or two conspicuous signatures in Doppler radar imagery, have...
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Evaluation of the capacity and delay benefits of terminal air traffic control automation
April 14, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-192
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Summary
This report reviews the benefits that the CTAS component of the FAA Terminal Air Traffic Control Automation program (TATCA) offers to aviation users. In particular, the report evaluates the prospects that exist for increasing arrival capacity during Instrument Meteorological Conditions (IMC) by introducing CTAS functionality into current operations. The impact of anticipated capacity gains on air traffic delays is analyzed. Savings in delay are translated into dollar savings using FAA statistics on the fleet-weighted direct cost of delay to domestic air carriers. Also, the value of passenger time is considered. Economic impacts are estimated and reported on an annualized, nationwide basis. Adopting FAA projections of future traffic growth, estimates of delay and attendant cost savings to air carriers and their passengers are provided for fiscal years 1995-2015. Taking the nominal estimate of a 12% gain in IMC arrival capacity, a nationwide implementation of CTAS would be estimated to save an average of 412,000 hours of air carrier delay annually over this 21-year period, and 273 million gallons of fuel per year. With current fuel and labor costs, this amounts to average direct operating savings to air carriers of $1.5 billion per year, and value to passengers of over $3 billion per year, in constant 1988 dollars. There may be factors outside the scope of this study that restrict the implementation of CTAS to certain sites, or that limit the weather conditions in which CTAS is effective. Methods are discussed in the report for modifying benefits estimates in response to such considerations. However, since development and implementation costs of CTAS are estimated to be a small fraction of the benefits enumerated above, and since the delay savings recur annually, it is concluded that the development of STC automation software such as CTAS is economically justifiable.
Summary
This report reviews the benefits that the CTAS component of the FAA Terminal Air Traffic Control Automation program (TATCA) offers to aviation users. In particular, the report evaluates the prospects that exist for increasing arrival capacity during Instrument Meteorological Conditions (IMC) by introducing CTAS functionality into current operations. The impact...
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Contributions to the American Meteorological Society's 26th International Conference on Radar Meteorology
April 1, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-199
Summary
Eleven papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 26th International Conference on Radar Meteorology, to be held May 24-28, 1993 in Norman, Oklahoma, are compiled in this volume. The work reported was sponsored by several FAA programs, including Terminal Doppler Weather Radar (TDWR), Air Surveillance Radar-9 (ASR-9), Integrated Terminal Weather System (ITWS), and Terminal Area Surveillance System (TASS). The papers are based on analyses completed over the past year at Lincoln Laboratory and in collaboration with staff at the National Severe Storms Laboratory, the University of Oklahoma, Raytheon Corporation, and the FAA Technical Center in Atlantic City, NJ. The staff members of the Weather Sensing Group have documented their studies in four major areas: Operational Systems (TDWR Operational Test and Evaluation results); Radar Operations (future airport weather surveillance requirements, a "machine intelligent" gust front detection algorithm, microburst asymmetry study results, a shear-based microburst detection algorithm, and a hazard index for TDWR-detected microbursts); Signal Processing (coherent processing across multi-PRI waveforms, clutter filter design for multiple-PRT signals, and identification of anomalous propagation associated with thunderstorm outflows); and Analysis Methods (multiple-single Doppler wind analysis using NEXRAD data, and an adjoint method wind retrieval scheme).
Summary
Eleven papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 26th International Conference on Radar Meteorology, to be held May 24-28, 1993 in Norman, Oklahoma, are compiled in this volume. The work reported was sponsored by several FAA programs, including Terminal Doppler Weather Radar (TDWR)...
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Two simulation studies of precision runway monitoring of independent approaches to closely spaced parallel runways
March 2, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-190
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Summary
This report documents the findings of two simulation studies of air traffic controller reaction to the Precision Runway Monitor (PRM). The PRM is a new system for monitoring independent approaches, to closely spaced parallel runways. It consists of a radar which has higher accuracy and a faster update interval than the current system. The PRM radar is accompanied by a high-resolution color display which provides automated visual and vocal warnings to alert controllers of impending and actual penetration of a 'No Transgression Zone' between parallel runways. The studies, were conducted in order to determine the effects of key variables on controller reaction time and to determine controller opinion on system acceptability. Study I examined the use of the PRM when the runway separation was both 3,400 ft and 4,300 ft. Study II examined the use of the PRM when the runway separation was 3,000 ft. Real-time simulated approach blunders were presented to controllers, and measurements of their reaction times were recorded and analyzed. Independent variables studied included sensor update interval, runway separation, deviation angle, deviation range, flight path condition, approach blunder type, and controller experience level. In addition, controller opinions of the PRM were surveyed. Findings regarding the effects of each of the variables are reported. Survey results of controller opinion are reported. Recommendations for enhancing the realism of the simulation and recommendations of issues for future study are discussed.
Summary
This report documents the findings of two simulation studies of air traffic controller reaction to the Precision Runway Monitor (PRM). The PRM is a new system for monitoring independent approaches, to closely spaced parallel runways. It consists of a radar which has higher accuracy and a faster update interval than...
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Machine intelligent gust front detection
March 1, 1993
Journal Article
Published in:
Lincoln Laboratory Journal, Vol. 6, No. 1, Spring 1993, pp. 187-212.
Summary
Techniques of low-level machine intelligence, originally developed at Lincoln Laboratory to recognize military ground vehicles obscured by camouflage and foliage, are being used to detect gust fronts in Doppler weather radar imagery. This Machine Intelligent Gust Front Algorithm (MIGFA) is part of a suite of hazardous-weather-detection functions being developed under contract with the Federal Aviation Administration. Initially developed for use with the latest generation Airport Surveillance Radar equipped with a wind shear processor (ASR-9 WSP), MIGFA was deployed for operational testing in Orlando, Florida, during the summer of 1992. MIGFA has demonstrated levels of detection performance that have not only markedly exceeded the capabilities of existing gust front algorithms, but are competitive with human interpreters.
Summary
Techniques of low-level machine intelligence, originally developed at Lincoln Laboratory to recognize military ground vehicles obscured by camouflage and foliage, are being used to detect gust fronts in Doppler weather radar imagery. This Machine Intelligent Gust Front Algorithm (MIGFA) is part of a suite of hazardous-weather-detection functions being developed under...
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Setting values for TDWR/LLWAS 3 integration parameters
February 5, 1993
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-195
Summary
In 1993 the FAA will begin deploying the Terminal Doppler Weather Radar (TDWR) at selected airports in the United States. Forty-five TDWRs will be collocated with LLWAS 3 systems, and the FAA has decided that all TDWRs collocated with LLWAS 3 systems must be integrated with LLWAS 3 prior to commissioning. The algorithm chosen to perform this integration must be supplied with a set of site-specific parameters. This report gives guidance on how to set the values of theme integration parameters.
Summary
In 1993 the FAA will begin deploying the Terminal Doppler Weather Radar (TDWR) at selected airports in the United States. Forty-five TDWRs will be collocated with LLWAS 3 systems, and the FAA has decided that all TDWRs collocated with LLWAS 3 systems must be integrated with LLWAS 3 prior to...
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