MITRE CAASD's RNAV Takes Aim at Improving Airport Efficiency

June 1999

In an era where over 500 million passengers fly in the United States each year, improving airline schedule predictability and efficiency, while maintaining a high standard of safety, remains a top priority of the U.S. Federal Aviation Administration (FAA). In support of our partnership with the FAA, MITRE's Center for Advanced Aviation System Development (CAASD) has been working collaboratively with the FAA and USAirways, Inc., to identify, develop, and assess various near-term terminal area procedures that will improve airline service. The goal of these procedures is to reduce pilot and controller workload, increase safety, enhance schedule predictability, improve operational efficiency, and reduce overall aircraft delays. This project, called Area Navigation (RNAV) Route Development activity, began in early 1999 with Phase I—the development and implementation of these procedures at the Philadelphia International Airport.

Prior to the development of RNAV routes, aircraft traveling to and from the Philadelphia airport often suffered from poor on-time performance, disrupted bank schedules, and passenger delays. One primary reason for these problems was the mandatory miles-in-trail restrictions at the Terminal Radar Approach Control (TRACON) entry/exit fixes. These restrictions required ad hoc vectoring of aircraft, not only to fly in the airspace where routes are not currently defined, but also to achieve desired aircraft separations. Consequently, flying over these extended paths cost time and fuel, and resulted in aircraft delays. To remedy the problem and to minimize variances between desired versus actual flight paths and to improve schedule predictability, the FAA, MITRE/CAASD and USAirways sought to define efficient routes to and from the airport. To do so, CAASD developed the Terminal Area Route Generation, Evaluation and Traffic Simulation (TARGETS), a subset of the Terminal Route Using Speed Control Techniques (TRUST) system, and adapted it specifically for use in TRACON airspace. As Jeff Formosa the CAASD project facilitator explains, "The TARGETS system is the tool that helped us design efficient and reliable paths for airplanes to fly. It's efficient because it benefits fuel economy and airspace use yet it's reliable enough to allow for reduced communications between pilots and air traffic controllers because the controllers know the exact position of the plane."

RNAV Route Development Team members from left to right are: Tom Becher, Mark Huberdeau, Steve Chase, Chad Grube, Jen Harding, Barry Wise, Kelly Connolly, and David Eccleston. Team members not available for photo include: Jeff Formosa, David Domino and Greg Tennille.

The project began with the formation of the Philadelphia RNAV route development team tasked with defining more efficient routes to and from the airport. The first meeting occurred in Philadelphia on February 2, 1999, and included seventeen representatives from the FAA, Philadelphia Tower/TRACON, USAirways, Inc., and CAASD. Since that initial meeting, CAASD has had a major role in the design and assessment of the RNAV route.

One of CAASD's primary roles on this project was the creation and documentation of the RNAV implementation process and project steps. The team's work included the development of a repeatable process used to ensure that the necessary activities are completed, major milestones are met and tasks are assigned and completed. The team also ensures that the overall process is critical-path observant, streamlined, and efficient. Kelly Connolly, the CAASD project team manager, stresses the importance of the process. "One of the true benefits of this project is the repeatable process—it reduces implementation time from two or more years to approximately eight months."

Beyond the development of the repeatable process, CAASD also adapted TARGETS for the terminal area. The team used TARGETS to define the RNAV route by depicting the route profile, deriving latitude and longitude coordinates for the proposed waypoints, and running preliminary flyability checks with respect to aircraft performance characteristics. The new RNAV route permits equipped aircraft to self-navigate all the way to touchdown. By contrast, aircraft unequipped with Area Navigation capabilities fly the conventional vectors. This new approach reduces the number of controller clearances (voice communications) from approximately eight to two or three. "Reduced voice communications is a clear sign of increased efficiency and reduced workload," says Connolly. "Furthermore, the controllers know precisely where the aircraft are flying thereby improving situational awareness. " In addition, because the route permits the aircraft to self-navigate all the way to touchdown, there are fewer altitude crossing restrictions and required speed assignments. The result is a more predictable flight path than the flight path variations that result from current pilot/controller practices.

Chad Grube and Tom Becher developing an RNAV route for Philadelphia International Airport using TARGETS.

Another major portion of CAASD's contributions to the project centered on the successful installation of the TARGETS system at the Philadelphia airport and the training of air traffic controllers in the use of the new RNAV procedure. Phase I route development consisted of a route that overlays the conventional paths used by controllers for inbound flights. "While our team had a major role in the development of software tools for TARGETS, we were also on site helping the Philadelphia controllers learn to use our route design tool to define waypoints for an RNAV approach to a specific runway, " explains Jen Harding, a CAASD software development engineer.

Preliminary Results and Future Developments

At present, the FAA, USAirways, and MITRE/CAASD are pleased with the use of TARGETS at the Philadelphia International Airport. As CAASD's Connolly remarks, "The success of Phase I is largely attributable to the dedication, experience and knowledge of the team members." Even the team members have found the process to be an educational and rewarding experience. Chad Grube, a CAASD software developer observes, "As part of the TARGETS team, CAASD staff has worked with a wide variety of people throughout Phase I. The exposure to all sides of the project has given us a unique holistic perspective on the process of defining RNAV procedures within terminal airspace. This perspective is a vital part of solving the problem since the procedures defined must satisfy each and every requirement presented in order to be implemented and used effectively."

A 30-day live field trial utilizing USAirways revenue flights will occur in the summer of 1999. Upon completion of the live test period—and barring any unexpected issues—the RNAV route will be flown by USAirways, wind and weather permitting, on a regular basis. Furthermore, the special approach plate will become available for use by all other carriers that are properly equipped. The other carriers will be advised of the new RNAV route and will be asked to have their crews prepare to fly the route on a common date, expected to be in fall of 1999.

Future developments include an expansion of the route development process that will capture other arrival and departure routes at the Philadelphia airport. In addition, CAASD has begun RNAV route development activities at the Newark airport (New York TRACON) with flight tests occurring on the new arrival routes this summer. RNAV development work at two more sites is scheduled for the year 2000.

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