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The Center News
FAA William J. Hughes Technical Center
Atlantic City Airport, New Jersey

May 08, 2003
By Nancy Tucker and Nancy Dorighi
NASA Ames Research Center

(Any questions about the content of this article, please contact Karen Buondonno, ACB-330)

D/FW Perimeter Taxiway Demonstration: FAA & NASA working together

In February 2003, Dallas/Fort Worth International Airport's study of their perimeter taxiway concept culminated with a simultaneous real-time demonstration at NASA Ames' FutureFlight Central and B747-400 simulators. In collaboration with NASA, the FAA William J. Hughes Technical Center Simulation and Analysis Group (ACB-330) provided the Principle Investigator, the simulation design, data analysis, and technical report.

Proposed taxiway system at DFW (highlighted).

Participants in the demonstration included five certified FAA controllers from the DFW tower and seven pilot representatives from the airlines and pilot unions. Five of the pilots were active pilots with large, commercial aircraft experience. For the first time, users jointly experienced a future airport design in real time.

The demonstration ran for four days with controllers managing DFW traffic at future demand levels, an approximate 20 - 30 % increase over estimated current traffic levels. Traffic was run under the current airport configuration and with the perimeter taxiways for comparison. On conclusion of the project and after each run, controllers and pilots evaluated various aspects of the demonstration.

What are some of the preliminary results? FAA ACB-330's initial analysis reported that both controller and pilot surveys rated the perimeter taxiways as an improvement.

Survey Question: Based on your experience in the demonstration, do you feel that adding the PTs improves operations at DFW? 1= Not At All, 7 = A Great Deal

Controllers also asserted that perimeter taxiways reduced frequency congestion and analysis of a sample of recorded voice communication supported this perception: There were fewer transmissions. However, it is important to note that this is demonstration, not operational data, with factors affecting its precision.

During the Baseline runs, there was an average of 147 runway crossings per hour. Perimeter taxiways completely eliminated runway crossings at DFW under the conditions simulated for the demonstration.

To address concerns, pilots flew profiles of landing and departing aircraft with perimeter-taxiing aircraft below. All participating pilots requested views of a worst case scenario, specifically an engine loss at maximum gross weight at takeoff. Participants seemed comfortable that traffic cleared the perimeter taxiways with at least a margin of several hundred feet and found that all safety standards and clearance boundaries were satisfactory.

Prior to the demonstration week, controllers had the opportunity to refine the operational procedures for managing perimeter taxiway traffic. A choke point was identified during pre-demonstration Shakedown Runs where east and west side arrivals passed through the same intersection. Controllers modified their procedures to alleviate this bottleneck, redirecting some of the traffic from the East Side to a nearby taxiway, thus reducing traffic levels at the intersection.

Jim Crites, Executive Vice-President, Airport Operations at DFW summed up the demonstration: “The perimeter taxiway project has been a labor of love for ten years. However, DFW didn't have the tools to solve the critical question: how the changes would affect the operators. [The FutureFlight and CVSRF] system fills in a critical component.”

He concluded by saying that an informational video of the demonstration will be shared with NATCA, ICAO, National Academy of Sciences, International Council of Airports, ALPA, and APA, among others. It will show how both management and the user community were brought together. “This is one of the most critical messages; here we had honest dialogue. It was a big win for all parties.”

DFW will formally release the demonstration findings and the informational video at a press conference in June.