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HIGHLIGHTS ARCHIVE
09.14.11
Division Highlights

Contents
Kick-off meeting starts project exploring Dynamic Airspace Configuration in response to Uncertain Weather
A team consisting of experienced air traffic management researchers from Metron Aviation, Intelligent Automation Incorporated, and State University of New York at Stony Brook presented a research plan for Dynamic Airspace Configuration in response to uncertain weather at NASA Ames Research Center. Severe weather makes regions of airspace unsuitable for air traffic, so flights are delayed and rerouted to avoid this severe weather. The resulting flight patterns around weather can be considerably different than the normal flight patterns that the current static airspace boundaries divide into regions of traffic appropriate for management by a single team of air traffic controllers. This mismatch can lead to overworked air traffic controllers, which can cause even more delayed and rerouted flights. The team presented methods for dynamically adjusting airspace boundaries so that they better handle the unusual and uncertain flight patterns that result from severe weather. Severe weather is difficult to predict accurately, as are the flight patterns that will result from severe weather, so the research will design airspace boundaries that are robust to relevant uncertainties. Approaches for coordinating changes to flight patterns with airspace boundary changes were also presented. The team will evaluate their approaches with simulations conducted in the Airspace Concept Evaluation System (ACES), an air traffic simulator developed at NASA Ames Research Center. (POC: Michael Bloem)

Graphic showing the SoCal TRACON airspace surrounding LAX airport
Terminal TSAFE study simulated the Southern California TRACON airspace surrounding Los Angeles International Airport

Second Simulation for Terminal TSAFE Research (T-TSAFE)
The second Terminal Tactical Separation Assurance Function (T-TSAFE) experiment was completed August 20th after two weeks of data collection in the Aviation Systems Divsion ATC Lab. The T-TSAFE concept takes TSAFE, as developed for use in Centers, and adapts it for use in Terminal airspace. Terminal airspace is more crowded and has more complicated separation criteria than high altitude airspace. Terminal TSAFE is expected to reduce the number of false alerts, and provide conflict resolution to controllers. The experiment simulated the SoCal Terminal Radar Approach Control (TRACON) airspace surrounding the Los Angeles International airport because of the complexity of this airspace. The focus of the second T-TSAFE human-in-the-loop experiment was adding altitude-based conflict resolutions for the controllers. The experiment added refinements to the T-TSAFE controller interface. It also tested T-TSAFE conflict alerts in the final approach all the way to the threshold instead of using Automated Terminal Proximity Alert (ATPA) on the final approach and T-TSAFE in the rest of the TRACON. In addition to digital data, the study assessed controller workload, situation awareness, trust, and obtained controller feedback on operational procedures. (POC: Savvy Verma and Debbi Ballinger)

Graphic showing the LCTR and with Hanger 1 and Ames Research Center in the background
Large Civil Titl Rotor simulation at NASA Ames Research Center

Large Civil Tilt-Rotor (LCTR) Handling Qualities Evaluation on the Vertical Motion Simulator (VMS)
A four-week long, joint NASA/Army simulation study in the Vertical Motion Simulator (VMS) investigated flight control design and handling quality issues of a 100-passenger Large Civil Tilt-Rotor (LCTR). The primary objective was to study the influence of nacelle actuation bandwidth on handling qualities in the hover/low speed flight regime with a Translational Rate Command (TRC) flight control system, and to develop supplementary control augmentation to improve handling qualities. The secondary objective was to investigate civil area procedures and operations, and handling qualities during forward flight and transition to hover. An enhanced stability derivative math model was developed to simulate the LCTR with fully moveable nacelles and a flight envelope up to 120 knots. Eleven experimental test pilots from NASA, the U.S. Army, U.S. Marine Corps, Bell Helicopter, Boeing and Sikorsky performed formal handling quality evaluations using carefully designed evaluation tasks. The high-fidelity motion cueing capability was also used to explore refinements to the control laws as well as pilot control technique. Preliminary results show that, as anticipated, lower actuator bandwidth configurations resulted in degraded handling qualities. Significant improvement in the handling qualities was observed when supplementary control augmentations, such as response quickening control laws and augmenting nacelle actuation with longitudinal cyclic, were used. The pilots were impressed with the simulation, with one stating that the VMS was “a valuable tool” for this type of research. (POC: Steve Beard and Emily Lewis)

Photo showing simulation pilots during a Trajectory-Based Automation System (TBAS) simulation in the Boeing 747-400 simulator at NASA Ames Research Center.
Trajectory-Based Automation System (TBAS) simulation in the Boeing 747-400 simulator

Successful Simulation with Controllers and Pilots in the Loop Demonstrates Viability of Efficient New Weather-Avoidance Routing Capability
On September 2, 2011, the “Trajectory-Based Automation System for En Route and Transition Airspace” (TBAS-ET) project successfully completed a two-week simulation evaluation with controllers and pilots in the loop. This TBAS-ET simulation studied a trajectory-based air traffic management operational concept that encompasses the use of datalink communication in a near-term, mixed-equipage environment. Initial results support the conclusion that significant operational efficiencies can be achieved by issuing complex yet efficient weather-avoidance routes via datalink communication. Furthermore, such operations appear to be viable even in the near-term future, before data communications are ubiquitous. In addition to investigating strategic and tactical weather avoidance, the simulation also evaluated new clearance procedures to improve controller/pilot communications, automated conflict resolution advisories, and improved tactical conflict detection (using the ground-based “Tactical Separation-Assisted Flight Environment” or TSAFE algorithm). (POC: Chester Gong)

Researchers Achieve Significant Improvement in Climb Trajectory Prediction
A new technique developed by NASA researchers has reduced climb-trajectory prediction errors by as much as 90% in laboratory testing. Aircraft climb trajectories are the most difficult to project; high errors in this regime increase the rate of false and missed alerts from separation assurance automation and reduce the potential operational benefits of some advanced concepts for NextGen. In simulations with fuel weight uncertainty of up to 50% (or roughly 15% of gross weight), the algorithm is able to adapt to within 1% of gross weight within two minutes. As a result, the standard deviation of five-minute prediction altitude errors declined by 90%, from about 1000 ft to 100 ft. When uncertainties in climb speed and climb mach were modeled (at up to 10% each), the algorithm still improved climb prediction accuracy by 20-40% (roughly 300 to 600 feet). Based on these results, the adaptive climb-trajectory prediction algorithm is slated for integration into the trajectory predictor of CTAS (Center/TRACON Automation System), NASA's real-time ground-based prototype system. (POC: David Thipphavong and Charles Schultz)

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