== Abstract ==

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The nation's air-traffic-control system is the subject of an extensive modernization program, including the planned introduction of advanced automation techniques. This paper gives an overview of a concept for automating terminal-area traffic management. Four-dimensional (4D) guidance techniques, which play an essential role in the automated system, are reviewed. One technique, intended for on-board computer implementation, is based on application of optimal control theory. The second technique is a simplified approach to 4D guidance intended for ground computer implementation. It generates advisory messages to help the controller maintain scheduled landing times of aircraft not equipped with on-board 4D guidance systems. An operational system for the second technique, recently evaluated in a simulation, is also described.

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== Original document ==

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The different versions of the original document can be found in:

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* [http://www.aviationsystemsdivision.arc.nasa.gov/publications/1984/AF1984101.pdf http://www.aviationsystemsdivision.arc.nasa.gov/publications/1984/AF1984101.pdf]

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* [http://xplorestaging.ieee.org/ielx5/4788337/4788338/04788371.pdf?arnumber=4788371 http://xplorestaging.ieee.org/ielx5/4788337/4788338/04788371.pdf?arnumber=4788371],

: [http://dx.doi.org/10.23919/acc.1984.4788371 http://dx.doi.org/10.23919/acc.1984.4788371]

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* [https://ntrs.nasa.gov/search.jsp?R=19850065532 https://ntrs.nasa.gov/search.jsp?R=19850065532],

: [https://www.infona.pl/resource/bwmeta1.element.ieee-art-000004788371 https://www.infona.pl/resource/bwmeta1.element.ieee-art-000004788371],

: [http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.ieee-000004171300 http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.ieee-000004171300],

: [https://repository.exst.jaxa.jp/dspace/handle/a-is/389744 https://repository.exst.jaxa.jp/dspace/handle/a-is/389744],

: [https://academic.microsoft.com/#/detail/2151488409 https://academic.microsoft.com/#/detail/2151488409]

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