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

Published in:
MIT Lincoln Laboratory Report ATC-258

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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AM-FM separation using auditory-motivated filters

Published in:
IEEE Trans. Speech Audio Process., Vol. 5, No. 5, September 1997, pp. 465-480.

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

Author:
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.

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

Published in:
Air Traffic Control Q., Vol. 5, No. 1, January 1997, pp. 49-68.

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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Automated English-Korean translation for enhanced coalition communications

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

Published in:
IEEE Microw. Guid. Wave Lett., Vol. 7, No. 1, January 1997, pp. 15-17.

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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ITWS microburst prediction algorithm performance, capabilities, and limitations

Summary

Lincoln Laboratory, under funding from the Federal Aviation Administration (FAA) Terminal Doppler Weather Radar program, has developed algorithms for automatically detecting microbursts. While microburst detection algorithms provide highly reliable warnings of microbursts. there still remains a period of time between microburst onset and pilot reaction during which aircraft are at risk. This latency is due to the time needed for the automated algorithms to operate on the radar data, for air traffic controllers to relay any warnings and for pilots to react to the warnings. Lincoln Laboratory research and development has yielded an algorithm for accurately predicting when microburst outflows will occur. The Microburst Prediction Algorithm is part of a suite of weather detection algorithms within the Integrated Terminal Weather System. This paper details the performance of the Microburst Prediction Algorithm over a wide range of geographical and climatological environments. The paper also discusses the full range of the Microburst Prediction Algorithm's capabilities and limitations in varied weather environments. This paper does not discuss the overall rationale for a prediction algorithm or the detailed methodology used to generate predictions.
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Summary

Lincoln Laboratory, under funding from the Federal Aviation Administration (FAA) Terminal Doppler Weather Radar program, has developed algorithms for automatically detecting microbursts. While microburst detection algorithms provide highly reliable warnings of microbursts. there still remains a period of time between microburst onset and pilot reaction during which aircraft are at...

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A comparative performance study of TDWR/LLWAS 3 integration algorithms for wind shear detection

Author:
Published in:
Workshop on Wind Shear and Wind Shear Alert Systems, Oklahoma City, 13-15 November, 1996.

Summary

This paper gives a brief overview of the history of the development of the TDWR/LLWAS 3 integration algorithms, a brief overview of the various algorithms, and a discussion of the comparative evaluation of the TDWR, LLWAS 3, and the three candidate TDWR/LLWAS 3 integration algorithms. This is followed by a more detailed description of the TDWR/LLWAS 3 integration algorithm chosen by the FAA for production, and a brief overview of the ITWS/LLWAS 3 integration algorithm.
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Summary

This paper gives a brief overview of the history of the development of the TDWR/LLWAS 3 integration algorithms, a brief overview of the various algorithms, and a discussion of the comparative evaluation of the TDWR, LLWAS 3, and the three candidate TDWR/LLWAS 3 integration algorithms. This is followed by a...

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ASR-9 Weather Systems Processor (WSP): wind shear algorithms performance assessment

Published in:
Workshop on Wind Shear and Wind Shear Alert Systems,. Oklahoma City, 13-15 November, 1996.

Summary

Under Federal Aviation Administration sponsorship, Lincoln Laboratory has developed a prototype Airport Surveillance Radar Weather Systems Processor (ASR-WSP). This prototype has been used for field measurements and operational demonstrations since 1987. Measurements so acquired provide an extensive database for development and validation of the algorithms used by the WSP to generate operational wind shear information for Air Traffic Controllers. In this paper we assess the performance of the current versions of the WSP's microburst and gust front wind shear detection algorithms on data from each of the locations at which our prototype system has operated. Evaluation of the associated environmental characteristics (e.g., storm structure, radar ground clutter environment) allows for generalization of these results to the major U.S. climatic regimes where the production version of WSP will be deployed.
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Summary

Under Federal Aviation Administration sponsorship, Lincoln Laboratory has developed a prototype Airport Surveillance Radar Weather Systems Processor (ASR-WSP). This prototype has been used for field measurements and operational demonstrations since 1987. Measurements so acquired provide an extensive database for development and validation of the algorithms used by the WSP to...

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Analysis of the 12 April 1996 wind shear incident at DFW airport

Published in:
Workshop on Wind Shear and Wind Shear Alert Systems, 13-15 November, 1996.

Summary

Wind shear detection algorithms that operate on Doppler radar data are tuned to primarily recognize the velocity and reflectivity signatures associated with microbursts and gust fronts. Microbursts produce a divergent pattern in the velocity field that is associated with a descending column of precipitation. Gust fronts produce a convergent pattern that is often associated with a thin-line reflectivity feature. On April 12, 1996 at Dallas-Fort Worth International Airport (DFW) three pilots reported encounters with wind shear in a five minute period (2329-33 GMT). The third pilot (AA 1352) reported an encounter with "severe wind shear", which we refer to as "the incident" throughout the paper. He used maximum throttle to keep the MD-80 in the air and reported that it was only "by the grace of God" that the aircraft did not crash (Dallas Morning News, 4/19/96). The plane, originally bound for Pittsburgh, was diverted to Tulsa where the passengers were offloaded to another aircraft, the black box was removed, and the engines were checked according to procedures required whenever maximum throttle is utilized.
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Summary

Wind shear detection algorithms that operate on Doppler radar data are tuned to primarily recognize the velocity and reflectivity signatures associated with microbursts and gust fronts. Microbursts produce a divergent pattern in the velocity field that is associated with a descending column of precipitation. Gust fronts produce a convergent pattern...

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