Aisha Bowe

A conflict resolution algorithm is introduced that enables a user to specify the degree to which fuel economy is prioritized relative to airborne delay, analogous to the “cost index" setting in flight management computers. Fast-time simulations of current-day traffic levels in two regional airspaces under nominal weather conditions are simulated to evaluate the benefit of modifying a conflict resolution algorithm to select resolution maneuvers based on minimum cost. The study employs the use of… Show more

A conflict resolution algorithm is introduced that enables a user to specify the degree to which fuel economy is prioritized relative to airborne delay, analogous to the “cost index" setting in flight management computers. Fast-time simulations of current-day traffic levels in two regional airspaces under nominal weather conditions are simulated to evaluate the benefit of modifying a conflict resolution algorithm to select resolution maneuvers based on minimum cost. The study employs the use of a parameter to represent the relative importance of fuel burn price to delay price. Additionally, the price of fuel burn and delay relative to one another is varied from the nominal in order to illustrate the differences in the algorithmic behavior should the delay or fuel price increase. Results show the lowest total operational cost occurs when the relative importance of delay to fuel burn price is equally weighted. Overall, minimizing fuel burn when selecting resolutions based on cost results in a lower operational cost than minimizing delay. The sensitivity of total operational cost to resolution types is presented. Implications of these findings for advanced separation assurance concepts are discussed. Show less

One of the complicating factors when detecting and resolving aircraft-to-aircraft conflicts is the presence of uncertainty, which can cause conflicts to be detected without sufficient time to resolve them. Previous work by the authors has shown this situation occurs most often when the uncertainties affect the trajectory of an aircraft near or in its descent phase. This paper attempts to address this issue by exploring a pair of enhanced vertical conflict detection ranges (buffers) for… Show more

One of the complicating factors when detecting and resolving aircraft-to-aircraft conflicts is the presence of uncertainty, which can cause conflicts to be detected without sufficient time to resolve them. Previous work by the authors has shown this situation occurs most often when the uncertainties affect the trajectory of an aircraft near or in its descent phase. This paper attempts to address this issue by exploring a pair of enhanced vertical conflict detection ranges (buffers) for descending aircraft that could provide enough coverage to catch all potential losses near and during descent for multiple types of uncertainty while minimizing the increase in the rate of false alerts. The paper examines uncertainties in the prediction of wind speed, cruise speed, descent speed, top-of-descent location, and the combination of all of those uncertainties plus uncertainty in aircraft weight prediction. The vertical conflict detection buffers are designed to improve performance of the conflict prediction and resolution tools near or after the top-of-descent, so the focus will be on conflicts involving at least one aircraft that is an arrival. These vertical conflict detection buffers should also be tunable to different levels of trajectory prediction accuracy. Therefore, for a known range of uncertainty, there should exist a minimum vertical buffer that will detect all of the conflicts that could occur near or after the top-of-descent. Therefore a second goal of this work is to show that these buffers can be adapted to fit a given range of uncertainty, so that as trajectory predictions improve, the vertical conflict detection ranges can be decreased to reduce the number of false alerts while maintaining safe separation. Finally, the impact of these vertical detection buffers on the conflict resolution process is examined. With buffers tuned to the amount of trajectory prediction error, the total delay as a function of trajectory prediction error is presented. Show less

This experiment evaluates the benefit of augmenting a conflict detection and resolution algorithm to consider a fuel-efficient, Variable Speed Direct-To maneuver when resolving a given conflict based on either minimum fuel burn or minimum delay. Twelve conditions were tested in fast-time simulation conducted in three airspace regions with mixed aircraft types and nominal traffic. Inclusion of this maneuver had no appreciable effect on the ability of the algorithm to safely detect and resolve… Show more

This experiment evaluates the benefit of augmenting a conflict detection and resolution algorithm to consider a fuel-efficient, Variable Speed Direct-To maneuver when resolving a given conflict based on either minimum fuel burn or minimum delay. Twelve conditions were tested in fast-time simulation conducted in three airspace regions with mixed aircraft types and nominal traffic. Inclusion of this maneuver had no appreciable effect on the ability of the algorithm to safely detect and resolve conflicts. Cumulative fuel burn savings were significantly higher when selecting resolutions based on minimum fuel burn; average delay per resolution was only marginally higher.


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Automated separation assurance algorithms are envisioned to play an integral role in accommodating the forecasted increase in demand of the National Airspace System. Developing a robust, reliable, air traffic management system involves safely increasing efficiency and throughput while considering the potential impact on users. This experiment seeks to evaluate the benefit of
augmenting a conflict detection and resolution algorithm to consider a fuel efficient, Zero-Delay Direct-To… Show more

Automated separation assurance algorithms are envisioned to play an integral role in accommodating the forecasted increase in demand of the National Airspace System. Developing a robust, reliable, air traffic management system involves safely increasing efficiency and throughput while considering the potential impact on users. This experiment seeks to evaluate the benefit of
augmenting a conflict detection and resolution algorithm to consider a fuel efficient, Zero-Delay Direct-To maneuver, when resolving a given conflict based on either minimum fuel burn or minimum delay. A total of eight conditions were tested in a fast-time simulation conducted in two airspace regions with mixed aircraft types and light weather. Results show that inclusion of this maneuver has no appreciable effect on the ability of the algorithm to safely detect and resolve conflicts. The results further suggest that enabling the Zero-Delay Direct-To maneuver significantly increases the cumulative fuel burn savings when selecting resolution based on minimum fuel burn while marginally increasing the average delay per resolution. Show less

Trajectory prediction is fundamental to automated separation assurance. Every missed alert, false alert and loss of separation can be traced to one or more errors in trajectory prediction. These errors are a product of many different sources including wind prediction errors, inferred pilot intent errors, surveillance errors, navigation errors and aircraft weight estimation errors. This study analyzes the impact of six different types of errors on the performance of an automated separation… Show more

Trajectory prediction is fundamental to automated separation assurance. Every missed alert, false alert and loss of separation can be traced to one or more errors in trajectory prediction. These errors are a product of many different sources including wind prediction errors, inferred pilot intent errors, surveillance errors, navigation errors and aircraft weight estimation errors. This study analyzes the impact of six different types of errors on the performance of an automated separation assurance system composed of a geometric conflict detection algorithm and the Advanced Airspace Concept Autoresolver resolution algorithm. Results show that, of the error sources considered in this study, top-of-descent errors were the leading contributor to missed alerts and failed resolution maneuvers. Descent-speed errors were another significant contributor, as were cruise-speed errors in certain situations. The results further suggest that increasing horizontal detection and resolution standards are not effective strategies for mitigating these types of error sources. Show less

The effects of selecting conflict resolution maneuvers based on minimum delay are compared to resolution selection based on minimum fuel burn. The algorithm used in this study is designed to support an automated separation assurance capability for next generation air traffic management systems. The algorithm resolves detected conflicts that are projected to be between three and twenty minutes prior to loss of separation. A total of nine fast-time simulations were conducted, each representing… Show more

The effects of selecting conflict resolution maneuvers based on minimum delay are compared to resolution selection based on minimum fuel burn. The algorithm used in this study is designed to support an automated separation assurance capability for next generation air traffic management systems. The algorithm resolves detected conflicts that are projected to be between three and twenty minutes prior to loss of separation. A total of nine fast-time simulations were conducted, each representing thirty six hours of traffic on a "low weather," high volume day with mixed aircraft types, flight phases and conflict geometries. The test matrix varied airspace region and resolution selection criteria. System-wide effects such as the number of conflicts, fuel burn, delay, and maneuver type are analyzed and compared to the same metrics when maneuvers are selected based on delay. When selecting resolutions based on fuel burn, the cumulative fuel burn of the system decreases by 27% and the delay increases by 25% when compared to resolutions selected based on minimum delay. Results indicate that speed maneuvers are the most efficient when selecting resolutions based on minimum fuel burn. Horizontal and vertical maneuvers were executed with similar frequency when comparing delay and fuel burn. Show less