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The impact of thunderstorm growth and decay on air traffic management in class B airspace

February 2, 1997
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Conference Paper
Author:
Bradley A. Crowe
…
Published in:
7th Conf. on Aviation, Range, and Aerospace Meteorology, ARAM, 2-7 February 1997.
Topic:
air traffic management
R&D area:
R&D group:

Summary

Air traffic management is a challenging task, especially if the airspace involved is impacted by inclement weather. The high volume of air traffic which inundates the nation's major airports compounds the difficulties with which Air Traffic Control (ATC) specialists have to cope. When you add the unpredictability of thunderstorm growth and decay to the controllers workload, air traffic management becomes even more of a challenge. ATC specialists would benefit from reliable forecasts of thunderstorm growth and decay. To determine how they would use a Growth and Decay product, ATC specialists from the Memphis Air Route Traffic Control Center (ARTCC), Traffic Management Unit (TMU), and TRACON supervisors were interviewed while viewing five movie loops of Memphis weather cases. The movies consisted of the ASR-9 six-level reflectivity data, aircraft beacons, and storm motion vectors.
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Summary

Air traffic management is a challenging task, especially if the airspace involved is impacted by inclement weather. The high volume of air traffic which inundates the nation's major airports compounds the difficulties with which Air Traffic Control (ATC) specialists have to cope. When you add the unpredictability of thunderstorm growth...

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The impact of thunderstorm growth and decay on air traffic management in class B airspace

The Memphis ITWS convective forecasting collaborative demonstration

February 2, 1997
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Conference Paper
Author:
Cynthia K. Mueller
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Published in:
7th Conf. on Aviation, Range, and Aerospace Meteorology, ARAM, 2-7 February 1997.
Topic:
detection systems
R&D area:
R&D group:

Summary

Accurate, short-term forecasts of where thunderstorms will develop, move and decay allow for strategic traffic management in and around the aviation terminal and enroute airspace. Pre-planning to avoid adverse weather conditions provides safe, smooth and continuous air traffic flow and savings in both fuel cost and time. Wolfson, et. al ( 1997) describe the problem of convective weather forecasting for FAA applications. In 1995, National Center for Atmospheric Research (NCAR), MIT Lincoln Laboratory (MIT-LL) and National Severe Storms Laboratory (NSSL) scientists and engineers agreed to collaborate on the development of a convective weather forecasting algorithm for use in airport terminal areas. Each laboratory brings special strengths to the project. NCAR has been developing techniques for precise, short-term (0-60 minutes) forecasts of thunderstorm initiation, movement and dissipation for the FAA over the past ten years and has developed the Auto-Nowcaster software. MIT-LL has been developing real-time algorithms for the Integrated Terminal Weather System (ITWS), including techniques for storm tracking, gust front detection, and calculating storm growth and decay (as part of predicting microbursts) . NSSL has been working on the NEXRAD Storm Cell Identification and Tracking (SCIT) algorithm, and on understanding the predictive value of the storm cell information. Thus by using the latest research results and best techniques available at each laboratory, the collaborative effort will hopefully result in a superior convective weather forecasting algorithm. Our goal in the immediate future is to develop a joint algorithm that can be demonstrated to users of terminal weather information, so that the benefits of convective weather forecast information can be realized, and the remaining needs can be assessed. As a first effort in the collaboration, the laboratories fielded their individual algorithms at the Memphis ITWS site. This paper gives an overview of our collaborative experiment in Memphis, the system each laboratory operated, some preliminary analysis of our performance on one case, and our plans for the near future.
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Summary

Accurate, short-term forecasts of where thunderstorms will develop, move and decay allow for strategic traffic management in and around the aviation terminal and enroute airspace. Pre-planning to avoid adverse weather conditions provides safe, smooth and continuous air traffic flow and savings in both fuel cost and time. Wolfson, et. al...

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The Memphis ITWS convective forecasting collaborative demonstration

Beacon radar and TCAS reply rates: airborne measurements in the 1090 MHz band

January 29, 1997
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Project Report
Author:
William H. Harman III
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Published in:
MIT Lincoln Laboratory Report ATC-256
Topic:
surveillance
R&D area:
R&D group:

Summary

The Federal Aviation Administration (FAA) is in the process of developing Automatic Dependent Surveillance Broadcast (ADS-B) techniques. In one candidate system, GPS-Squitter, each aircraft periodically broadcasts messages, called "squitters," that report the aircraft's identification, position, and velocity. The position and velocity information may be obtained from the Global Positioning System (GPS) or some other navigation device. Reception of squitters can be used for several purposes, including surveillance of airborne aircraft by a ground station, surveillance of aircraft on the airport surface, and air-to-air surveillance... In developing the new system, it is necessary to know the rates of existing signal transmissions in the 1030 and 1090 MHz frequency bands, which are the beacon-radar and TCAS interrogation channels. The GPS-Squitter would be transmitted in the 1090 MHz band, like a reply. A key issue is the possibility of interference to squitter reception from existing signals in the 1090 MHz band....To validate these initial calculations, Lincoln Laboratory has made direct measurements of the rates of existing transmissions in both bands. These signals consist mainly of interrogations in the 1030 MHz band and replies in the 1090 MHz band. This report focuses on airborne measurements that have been made at 1090 MHz. (Not complete)
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Summary

The Federal Aviation Administration (FAA) is in the process of developing Automatic Dependent Surveillance Broadcast (ADS-B) techniques. In one candidate system, GPS-Squitter, each aircraft periodically broadcasts messages, called "squitters," that report the aircraft's identification, position, and velocity. The position and velocity information may be obtained from the Global Positioning System...

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Beacon radar and TCAS reply rates: airborne measurements in the 1090 MHz band

Report on product performance for the Terminal Doppler Weather Radars (TDWRs) at Washington National Airport and Memphis and Orlando International Airports

January 29, 1997
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Project Report
Author:
Diana L. Klingle-Wilson
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Published in:
MIT Lincoln Laboratory Report ATC-246
Topic:
algorithms
R&D area:
R&D group:

Summary

Massachusetts Institute of Technology Lincoln Laboratory provides support to the Terminal Doppler Weather Radar (TDWR) Program Office in the performance analysis of deployed TDWR systems, and resulting recommendations for systems enhancements. This report documents initial performance of the TDWR products at Washington National Airport (DCA), Memphis International Airport (MEM) and Orlando International Airport (MCO). This performance depends, in turn, on the site optimization performed for the specific radars. Therefore, an overview of site optimization process, using DCA as a concrete example, is included. After the sites were optimized, base data (Doppler velocity and reflectivity) and product data (algorithm detections) were collected to assess the quality of the base data and the performance of the microburst and gust front detection algorithms. It is assumed that the reader of this report has an extensive knowledge of the TDWR system. (Not Complete)
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Summary

Massachusetts Institute of Technology Lincoln Laboratory provides support to the Terminal Doppler Weather Radar (TDWR) Program Office in the performance analysis of deployed TDWR systems, and resulting recommendations for systems enhancements. This report documents initial performance of the TDWR products at Washington National Airport (DCA), Memphis International Airport (MEM) and...

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Report on product performance for the Terminal Doppler Weather Radars (TDWRs) at Washington National Airport and Memphis and Orlando International Airports

Terminal area separation standards: historical development, current standards, and processes for change

January 16, 1997
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Project Report
Author:
Steven D. Thompson
Published in:
MIT Lincoln Laboratory Report ATC-258
Topic:
air traffic control
R&D area:
R&D group:

Summary

This paper gives an overview and summary of the separation requirements for air traffic control in the U.S. National Airspace System with emphasis on those relevant to terminal landing operations. These requirements are documented in the Federal Aviation Administration's (FAA's) Air Traffic Control Order 7110.65J, as ammended, and various national and local Orders. These requirements are also addressed in the Aeronautical Information Manual, the International Civil Aviation Organization's Standards and Recommended Practices, and the Federal Aviation Regulations (FARs). The purpose of this paper is to assist those people involved with the introduction of new technologies and procedures in the terminal airspace by providing them with an understanding of the separation requirements, the need for those requirements, and the processes used to change the requirements.
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Summary

This paper gives an overview and summary of the separation requirements for air traffic control in the U.S. National Airspace System with emphasis on those relevant to terminal landing operations. These requirements are documented in the Federal Aviation Administration's (FAA's) Air Traffic Control Order 7110.65J, as ammended, and various national...

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Terminal area separation standards: historical development, current standards, and processes for change

AM-FM separation using auditory-motivated filters

January 9, 1997
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Journal Article
Author:
Thomas F. Quatieri
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Published in:
IEEE Trans. Speech Audio Process., Vol. 5, No. 5, September 1997, pp. 465-480.
Topic:
signal processing
R&D area:
R&D group:

Summary

An approach to the joint estimation of sine-wave amplitude modulation (AM) and frequency modulation (FM) is described based on the transduction of frequency modulation into amplitude modulation by linear filters, being motivated by the hypothesis that the auditory system uses a similar transduction mechanism in measuring sine-wave FM. An AM-FM estimation is described that uses the amplitude envelope of the output of two transduction filters of piecewise-linear spectral shape. The piecewise-linear constraint is then relaxed, allowing a wider class of transduction-filter pairs for AM-FM separation under a monotonicity constraint of the filters' quotient. The particular case of Gaussian filters, and measured auditory filters, although not leading to a solution in closed form, provide for iterative AM-FM estimation. Solution stability analysis and error evaluation are performed and the FM transduction method is compared with the energy separation algorithm, based on the Teager energy operator, and the Hilbert transform method for AM-FM estimation. Finally, a generalization to two-dimensional (2-D) filters is described.
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Summary

An approach to the joint estimation of sine-wave amplitude modulation (AM) and frequency modulation (FM) is described based on the transduction of frequency modulation into amplitude modulation by linear filters, being motivated by the hypothesis that the auditory system uses a similar transduction mechanism in measuring sine-wave FM. An AM-FM...

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AM-FM separation using auditory-motivated filters

Sub-Poisson statistics observed in an electronically shuttered and back-illuminated CCD pixel

January 1, 1997
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Journal Article
Author:
Robert K. Reich
Published in:
IEEE Trans. Electron Devices, Vol. 44, No. 1, January 1997, pp. 69-73. Selected Papers on CCD and CMOS Imagers, SPIE Milestone Series, Vol. MS 177, 2003, pp. 169-173.
Topic:
electronics
R&D area:
R&D group:

Summary

The variance versus average signal has been measured for a pixel in an electronically shuttered and back-illuminated CCD imaging array. The measurements demonstrate that, over a certain operating range, the electronic shutter modifies the input Poisson distributed photoelectrons during the collection process such that the charge signal accumulated in the CCD well has a sub-Poisson distribution (variance less than a mean). A simple one-dimensional model has been developed that explains the experimental results.
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Summary

The variance versus average signal has been measured for a pixel in an electronically shuttered and back-illuminated CCD imaging array. The measurements demonstrate that, over a certain operating range, the electronic shutter modifies the input Poisson distributed photoelectrons during the collection process such that the charge signal accumulated in the...

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Sub-Poisson statistics observed in an electronically shuttered and back-illuminated CCD pixel

A comprehensive system for measuring wake vortex behavior and related atmospheric conditions at Memphis, Tennessee

January 1, 1997
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Journal Article
Author:
Timothy J. Dasey
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Published in:
Air Traffic Control Q., Vol. 5, No. 1, January 1997, pp. 49-68.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Models of vortex behavior as a function of atmospheric conditions are being developed in an attempt to improve safety and minimize unnecessary airport capacity restrictions due to wake vortices. Direct measurements of vortices and the relevant meteorological conditions in an operational setting, which would serve to improve the understanding of vortex behavior, are scarce and incomplete. A comprehensive vortex, meteorological, and aircraft measurement system has been constructed at Memphis International Airport and operated in two I-month periods during 1994 and 1995. A 10.6 um continuous-wave (CW) coherent lidar was used to measure vortex parameters with high fidelity. This lidar features a number of improvements over previous systems, including an automatic vortex detection and tracking algorithm to ensure efficient scanning. Meteorological data were collected from a 45 m instrumented tower, balloon soundings, a wind profiler/radio acoustic sounding system (RASS), sonic detection and ranging (SO DAR), and other sensors. This paper presents ensemble distributions of the conditions under which the over 500 aircraft were measured, and samples of vortex and atmospheric measurements. These data will be compared with theoretical predictions of vortex behavior as part of the development of an operational system designed to reduce aircraft spacings in the terminal area.
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Summary

Models of vortex behavior as a function of atmospheric conditions are being developed in an attempt to improve safety and minimize unnecessary airport capacity restrictions due to wake vortices. Direct measurements of vortices and the relevant meteorological conditions in an operational setting, which would serve to improve the understanding of...

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A comprehensive system for measuring wake vortex behavior and related atmospheric conditions at Memphis, Tennessee

Automated English-Korean translation for enhanced coalition communications

January 1, 1997
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Journal Article
Author:
Clifford J. Weinstein
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Published in:
Lincoln Laboratory Journal, Vol. 10, No. 1, 1997, pp. 35-60.
Topic:
machine translation
R&D area:
R&D group:

Summary

This article describes our progress on automated, two-way English-Korean translation of text and speech for enhanced military coalition communications. Our goal is to improve multilingual communications by producing accurate translations across a number of languages. Therefore, we have chosen an interlingua-based approach to machine translation that readily extends to multiple languages. In this approach, a natural-language-understanding system transforms the input into an intermediate-meaning representation called a semantic frame, which serves as the basis for generating output in multiple languages. To produce useful, accurate, and effective translation systems in the short term, we have focused on limited military-task domains, and have configured our system as a translator's aid so that the human translator can confirm or edit the machine translation. We have obtained promising results in translation of telegraphic military messages in a naval domain, and have successfully extended the system to additional military domains. The system has been demonstrated in a coalition exercise and at Combined Forces Command in the Republic of Korea. From these demonstrations we learned that the system must be robust enough to handle new inputs, which is why we have developed a multistage robust translation strategy, including a part-of-speech tagging technique to handle new works, and a fragmentation strategy for handling complex sentences. Our current work emphasizes ongoing development of these robust translation techniques and extending the translation system to application domains of interest to users in the military coalition environment in the Republic of Korea.
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Summary

This article describes our progress on automated, two-way English-Korean translation of text and speech for enhanced military coalition communications. Our goal is to improve multilingual communications by producing accurate translations across a number of languages. Therefore, we have chosen an interlingua-based approach to machine translation that readily extends to multiple...

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Automated English-Korean translation for enhanced coalition communications

45-GHz MMIC power combining using a circuit-fed, spatially combined array

January 1, 1997
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Journal Article
Author:
John T. Delisle
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Published in:
IEEE Microw. Guid. Wave Lett., Vol. 7, No. 1, January 1997, pp. 15-17.
Topic:
antennas
R&D area:
R&D group:

Summary

We describe the design and measurement of a hybrid-circuit, tile-approach subarray for use in spatial power-combined transmitters. The subarray consists of 16 monolithic millimeter-wave integrated circuit (MMIC) amplifiers, each feeding a circularly polarized cavity-backed microstrip antenna. The average performance across the 43.5-45.5 GHz band is as follows: EIRP 18.3 dBW, dc-RF efficiency 10.3%, effective transmitter power 530 mW, system gain 13.2 dB, and combining efficiency of 46.2%. The minimum axial ratio is 1.2 dB at 43.9 GHz, and the array has a 3% 3-dB axial ratio bandwidth.
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Summary

We describe the design and measurement of a hybrid-circuit, tile-approach subarray for use in spatial power-combined transmitters. The subarray consists of 16 monolithic millimeter-wave integrated circuit (MMIC) amplifiers, each feeding a circularly polarized cavity-backed microstrip antenna. The average performance across the 43.5-45.5 GHz band is as follows: EIRP 18.3 dBW...

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45-GHz MMIC power combining using a circuit-fed, spatially combined array
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