Nhut Ho

Continuous Descent Approach: Design and Flight Test for Louisville International Airport

A design methodology based on the principles of system analysis was used to design a noise abatement approach procedure for Louisville International Airport. In a flight demonstration test, the procedure was shown to reduce the A-weighted peak noise level at seven locations along the flight path by 3.9 to 6.5 dBA, and to reduce the fuel consumed during approach by 400 to 500 lb (181 to 227 kg). The noise reduction is significant given that a 3-dB difference represents a 50% reduction in acoustic energy and is noticeable to the human ear, and the 7% reduction in the size of the 50 day night average noise level (DNL) contour that would result if all aircraft were to perform the procedure. The fuel saving is also significant, given the financial benefit to airlines and the accompanying reduction in gaseous and particulate emissions. Although the analysis of aircraft performance data showed how pilot delay, in combination with auto-throttle and flight management system logic, can result in deviations from the desired trajectory, the results confirm that near-term implementation of this advanced noise abatement procedure is possible. The results also provide ample motivation for proposed pilot cueing solutions and low-noise guidance features in flight management systems.

Achieving low approach noise without sacrificing capacity

Advanced noise abatement procedures such as the three degree decelerating approach (TDDA) can significantly reduce the noise impact of aircraft during approach. With existing aircraft performance and flight operation uncertainties, however, implementation of the TDDA would require an increase in the initial separation between aircraft that would result in significant reduction in runway capacity. Simulation results indicate that this reduction in runway capacity is on the order of 50%, which is not acceptable for any procedure that must be used n high traffic scenarios. In this paper, we introduce a modified three degree decelerating approach (MTDDA) that provides the same noise benefits as the TDDA with little or no loss in capacity relative to conventional approach procedures. Simulation results indicate that for a representative aircraft mix, the capacity of the MTDDA is within 2% less of the maximum possible capacity using conventional approach procedures.

Engineering Trust in Complex Automated Systems

We studied the transparency of automated tools used during emergency operations in commercial aviation. Transparency (operationalized as increasing levels of explanation associated with an automated tool recommendation) was manipulated to evaluate how transparent interfaces influence pilot trust of an emergency landing planning aid. We conducted a low-fidelity study in which commercial pilots interacted with simulated recommendations from NASA’s Emergency Landing Planner (ELP) that varied in their associated levels of transparency. Results indicated that trust in the ELP was influenced by the level of transparency within the human–machine interface of the ELP. Design recommendations for automated systems are discussed.

Trust-Based Analysis of an Air Force Collision Avoidance System:

This case study analyzes the factors that influence trust and acceptance among users (in this case, test pilots) of the Air Force’s Automatic Ground Collision Avoidance System. Our analyses revealed that test pilots’ trust depended on a number of factors, including the development of a nuisance-free algorithm, designing fly-up evasive maneuvers consistent with a pilot’s preferred behavior, and using training to assess, demonstrate, and verify the system’s reliability. These factors are consistent with the literature on trust in automation and could lead to best practices for automation design, testing, and acceptance.

Methodology for Optimizing Parameters of Noise-Abatement Approach Procedures

Noise abatement approach procedures reduce the noise impact on communities surrounding airports by enabling aircraft to descend at lower power and along higher vertical path than standard approaches procedures. A design challenge of theses procedure is the selection of the procedure parameters that minimize the adverse impact of delay in the pilot response and uncertainty in the atmospheric condition. In this paper, a methodology developed to determine the optimum design parameters is presented. The methodology involved: 1) conducting a simulator-based, human factors experiment to obtain models of pilot delay in extending flaps/gear in conditions with and without turbulence; 2) formulating the procedure’s parameters as strategic and tactical control variables; 3) using the pilot delay models and the parameter formulation to perform a Monte Carlo Simulation to resolve the conflicting objectives of reducing noise and increasing probability of target achievement. Simulation results showed that the flap schedule has to be designed to get the aircraft to its desired speed at a target altitude that is 50-ft higher than the desired altitude when there is no turbulence, and 200-ft higher than the desired altitude when there is turbulence; 4) determining the feasibility space of the parameters in different wind conditions. Results showed that when the wind uncertainty is large, accounting for the uncertainty in the procedure design significantly reduces the effectiveness of the procedure. A discussion on the implementation of strategic and tactical control variables is also provided.

Shaping Trust Through Transparent Design: Theoretical and Experimental Guidelines

The current research discusses transparency as a means to enable trust of automated systems. Commercial pilots (N = 13) interacted with an automated aid for emergency landings. The automated aid provided decision support during a complex task where pilots were instructed to land several aircraft simultaneously. Three transparency conditions were used to examine the impact of transparency on pilot’s trust of the tool. The conditions were: baseline (i.e., the existing tool interface), value (where the tool provided a numeric value for the likely success of a particular airport for that aircraft), and logic (where the tool provided the rationale for the recommendation). Trust was highest in the logic condition, which is consistent with prior studies in this area. Implications for design are discussed in terms of promoting understanding of the rationale for automated recommendations.

Management of continuous descent approach during interval management operation

This paper reports on the performance and workload of pilots participating in a human-in-the-loop simulation of interval management operations during a continuous descent approach (CDA) into Louisville International Airport (SDF). The experiment examined variations in pilot roles and responsibilities in an implementation of interval management automation. The roles and responsibility manipulation showed that whether pilots were instructed to follow speed guidance strictly, or to exercise their own judgment, had no effect on workload and only a small effect on interval management performance. However, requiring the pilots to manually enter speeds into the autopilot, rather than having the automation automatically update the autopilot, frequently led to poorer energy management, and higher spacing interval errors at the final approach fix, even in the conditions where pilots were instructed to strictly follow speed guidance. This finding was traced to poorer compliance with the automated speed guidance, lack of awareness of this poor compliance, and insufficient awareness of the energy state of the aircraft. These results suggest that some form of energy guidance may be needed to augment interval management. To do this, recommendations were made for integrating the spacing interval management automation with near-term or far-term energy management systems. Workload measurement showed that, when pilots were required to maneuver to avoid en route weather, the manual conditions resulted in an increase in workload, although the overall level would still be considered low under normal circumstances.

Automated Spacing Support Tools for Interval Management Operations during Continuous Descent Approaches

In this study, pilots were asked to achieve a specific time in trail while flying an arrival into Louisville International airport. Weather shortly before the start of the descent added variability to the initial intervals. A spacing tool calculated airspeeds intended to achieve the desired time in trail at the final approach fix. Pilots were exposed to four experimental conditions which varied how strictly the pilots were told to follow these speeds and whether speeds had to be entered into the autopilot manually. Giving the pilots more discretion had little effect on the final spacing interval. However, pilots required to enter speeds into the autopilot manually did not effectively manage their airplanes energy resulting in less accurate performance. While these results may not always generalize to alternative spacing implementations, one should not assume pilots manually closing the loop on automated commands can perform as well as a fully automated system.

Trust of an automatic ground collision avoidance technology: A fighter pilot perspective.

The present study examined the antecedents of trust among operational Air Force fighter pilots for an automatic ground collision avoidance technology. This technology offered a platform with high face validity for studying trust in automation because it is an automatic system currently being used in operations by the Air Force. Pilots (N = 142) responded to an online survey which asked about their attitudes toward the technology and assessed a number of psychological factors. Consistent with prior research on trust in automation, a number of trust antecedents were identified which corresponded to human factors, learned trust factors, and situational factors. Implications for the introduction of novel automatic systems into the military are discussed.

A convergent frequency estimator

Online identification of sinusoidal components is an important problem that occurs in active noise control, vibration suppression, online health monitoring, and radar, sonar, and seismic applications. We adopt an approach to this identification problem which consists of the utilization of the underlying nonlinearity and an algorithm that is based on the nonlinear parameterization. The algorithm is shown to result in global convergence in the presence of two unknown frequencies. Extensions to n unknown frequencies for n/spl ges/2 that have unknown amplitudes are also discussed.