Problem Analysis Resolution and Ranking (PARR): Seeing What's Ahead

March 2002

	MITRE developed URET and PARR based on long-term research on strategic conflict detection and resolution capabilities. The corporation has been responsible for concept and requirement development, algorithms and software, operational evaluations, and for establishing metrics to resolve the problem.

MITRE technology provides air traffic controllers with enhanced decision-support capabilities to improve the services of the National Airspace System.

When air traffic controllers in Indianapolis and Memphis Centers manage the flow of traffic in their facilities, around 15,000 airplanes each business day, they have a number of important automation tools at their disposal. One significant one is MITRE's User Request Evaluation Tool (URET), which provides controllers with a "look-ahead" capability that notifies them of possible aircraft conflicts up to 20 minutes in the future.

"Twenty minutes is a significant extension of the time horizon for an air traffic controller," says Susan Schultheis, Center for Advanced Aviation System Development associate program manager for Enroute Decision Support System Evolution. "Early notification of problems promotes strategic planning at the sector. URET's trial planning feature enables controllers to consider various ‘what if?' options—such as a speed or altitude change—in order to solve a problem or respond to a pilot request."

With Problem Analysis, Resolution, and Ranking (PARR), an enhancement to URET, the system provides even more problem-resolution assistance to the controller. Using advanced algorithms built on URET's trajectory modeling and conflict detection functions, PARR provides real options for solving problems at the push of a button. It is still in the development phase, but MITRE believes it can be deployed as a URET enhancement in the next one to three years.

Enhanced decision support "PARR determines multiple potential options and then provides the controller with several possible courses of action, for example, a turn, an altitude change, or a speed change," adds Schultheis. Resolutions are generated and presented to the controller based on a number of operational factors that consider preferences of both controllers and pilots. With this information, the controller can accept the resolution as given or use it to support some other decision. The resolutions developed by PARR are designed to solve problems safely, preserve user preferences, and rapidly and efficiently present results to controllers in an operationally useful manner.

AVOIDING CONFLICT The red lines depict the paths of two aircraft causing a potential conflict situation. The green line shows a PARR-generated alternative flight path that would resolve the problem.

Understanding the Operational Environment

Developing a system that supports the needs of controllers requires a keen understanding of the way they do business. "In January and May [2001], we conducted field evaluations at Indianapolis Center to better understand the operational usefulness of a tool like PARR," explains Dave Winokur, Project Team Manager. "Overall, the evaluation feedback was positive and controllers felt that PARR provided usable and beneficial resolutions for today's air traffic control environment."

"We wanted to validate the operational acceptability and usability of the resolutions," continues Winokur. "For one thing, we learned from our field visits how to make the resolutions more usable in today's air traffic control environment, yet provide enough flexibility for future changes. Now, we're continuing to look at the algorithms and controller interface to determine how we can improve and refine them even further."

In January, members of MITRE's Air Traffic Conflict Probe Team participated in an evaluation of initial PARR capabilities in CAASD's Air Traffic Management lab in McLean, VA. This group, which consists of members designated from the National Air Traffic Controllers Association and the Federal Aviation Administration, is responsible for providing operational input and guidance throughout the design, planning, development, and deployment of URET and follow-on capabilities like PARR. "We're looking forward to making PARR capabilities available to controllers in the field," sums up Schultheis. "It is a terrific enhancement to an already effective system. It will really be a benefit to controllers and users of the National Airspace System."

—By Nadine Monaco

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