Air traffic control within the US is getting more complicated as the number of aircraft increases. There is a great need to increase the efficiency of the system so that flight delays are minimized without having to build new airports or runways. At the same time, safety must be maintained so that increased traffic levels do not lead to air traffic control-related incidents.

This work encompasses all components and tools currently existing within the Center/TRACON Automation System (CTAS), a software suite of real-time decision support tools for air traffic controllers. Tools covered by previous disclosures include Traffic Management Advisor (TMA), Passive Final Approach Spacing Tool (PFAST), Descent Advisor (DA), En-route Descent Advisor (EDA), Direct-To (D2), and Traffic Flow Automation System (TFAS). Related software also covered previously is the Pseudo Aircraft System (PAS), a software system for enabling real-time, controller-in-the-loop simulation of CTAS concepts. This disclosure covers all of the above, and in addition, includes the following: Terminal Sequencing and Spacing (TSAS), a tool to permit increased use of fuel-efficient arrival procedures in the terminal area; Active Final Approach Spacing Tool (AFAST), an extension of PFAST to provide active turn and heading advisories to controllers managing arrival aircraft in the terminal area; Expedite Departure Path (EDP), a tool for managing departure aircraft in the terminal area; and Tactical Separation-Assured Flight Environment (TSAFE), a short-term, tactical conflict probe tool.

TSAS is an extension of TMA that permits continued use of fuel-efficient arrival procedures in the terminal area during periods of moderate and high traffic congestion. TSAS uses a detailed model of the terminal portion of each flight's arrival procedure. The TSAS trajectory model specifically accounts for the speed and altitude constraints in the terminal area. It improves the TMA arrival schedule by also ensuring proper separation at additional key merge locations in the terminal area. Delay is allocated to the terminal area that maintains high airport throughput while conducting fuel-efficient arrival procedures. The TSAS arrival schedule is used by both en-route and terminal controllers to actively control the flights.

AFAST adds a significant new capability to the previous Passive FAST tool; namely, active controller advisories in the form of heading, speed, and altitude commands to achieve the desired trajectory and schedule for each aircraft. The AFAST scheduling algorithm systematically orders and merges aircraft from their current positions to their runway thresholds along an appropriate series of flight segments. This scheduling process consists of sequencing and conflict resolution. The sequencing algorithm uses fuzzy reasoning to determine the relative sequence of each pair of aircraft that share one or more flight segments. The conflict resolution algorithm uses decision trees of air traffic control tactics to resolve predicted conflicts among all scheduled aircraft. Solution trajectories are generated that are designed to be conflict-free with minimal excess separation between aircraft. Thus, each aircraft's solution trajectory reflects its earliest time of arrival while maintaining proper separation from other scheduled aircraft.

Similar to AFAST for arrivals, EDP generates active controller advisories for departures. EDP is a decision support tool aimed at providing terminal area (TRACON) Traffic Management Coordinators (TMCs) with pertinent departure traffic loading and scheduling information, and radar controllers with advisories for tactical control of TRACON departure traffic. EDP employs the CTAS trajectory synthesis routine to provide conflict-free altitude, speed, and heading advisories. These advisories will assist the TRACON departure controller in efficiently sequencing, spacing, and merging departure aircraft into the en-route traffic flow.

TSAFE is a critical new component originally conceived to provide a safety monitor for a future, highly automated air traffic control system. During development, it was discovered that it could be useful to controllers working in today's level of automation. In the context of the current CTAS system, TSAFE is a controller tool for detecting near-term conflicts and reducing the potential for operational errors.

Prior to the AFAST and EDP tools being available, controllers used manual decision-making to provide turn and speed advisories for arrivals and departures in the terminal area. TSAFE is the first of its kind in near-term conflict prediction that takes into account pilot and controller intent, but also accounts for possible pilot error. In this way, it is able to warn controllers of impending conflicts as a result of clearances as well as pilot errors.

Prior attempts to do this work have suffered from a lack of adequate fidelity in modeling aircraft performance, controller behavior and preferences, and realistically complex air traffic scenarios. That lack of fidelity led to automation algorithms that did not hold up under real-life conditions, or that were not acceptable to controllers. Those shortcomings have limited the applicability of such decision support tools.

This work was done by Douglas Isaacson, John Robinson, Yoon Jung, Russell Paielli, and Heinz Erzberger of Ames Research Center. This software is available for use. To request a copy, please visit here .

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This article first appeared in the July, 2017 issue of Tech Briefs Magazine.

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