Confesor Santiago

A Computer Simulation of the System-Wide Effects of Parallel-Offset Route Maneuvers

Modernization of the current air transportation system is an ongoing, incremental process. An early step in this modernization process is the implementation of enhancements to the Federal Aviation Administration’s (FAA’s) En Route Automation Modernization (ERAM) that supports en-route controllers in managing separation. This project is called Trajectory Based Operations (TBO) Separation Management: Modern Procedures. Research supporting this project involves computer human interface improvements to ERAM’s Decision Support Tools (DSTs) post Release 3 and algorithmic enhancements to the Conflict Probe to increase the usability of the tools for the near-term time frame of NextGen. One proposed algorithmic enhancement is to enable ERAM to model parallel-oset

The Generic Resolution Advisor and Conflict Evaluator (GRACE) for Detect-And-Avoid (DAA) Systems

The paper describes the Generic Resolution Advisor and Conflict Evaluator (GRACE), a novel alerting and guidance algorithm that combines flexibility, robustness, and computational efficiency. GRACE is “generic” in that it makes no assumptions regarding temporal or spatial scales, aircraft performance, or its sensor and communication systems. Accordingly, GRACE is well suited to research applications where alerting and guidance is a central feature and requirements are fluid involving a wide range of aviation technologies. GRACE has been used at NASA in a number of real-time and fast-time experiments supporting evolving requirements of DAA research, including parametric studies, NAS-wide simulations, human-in-the-loop experiments, and live flight tests.

UAS Well Clear Recovery Against Non-Cooperative Intruders Using Vertical Maneuvers

This paper documents a study that drove the development of a mathematical expression in the detect-and-avoid (DAA) minimum operational performance standards (MOPS) for unmanned aircraft systems (UAS). This equation describes the conditions under which vertical maneuver guidance should be provided during recovery of DAA well clear separation with a non-cooperative VFR aircraft. Although the original hypothesis was that vertical maneuvers for DAA well clear recovery should only be offered when sensor vertical rate errors are small, this paper suggests that UAS climb and descent performance should be considered—in addition to sensor errors for vertical position and vertical rate—when determining whether to offer vertical guidance. A fast-time simulation study involving 108,000 encounters between a UAS and a non-cooperative visual-flight-rules aircraft was conducted. Results are presented showing that, when vertical maneuver guidance for DAA well clear recovery was suppressed, the minimum vertical separation increased by roughly 50 feet (or horizontal separation by 500 to 800 feet). However, the percentage of encounters that had a risk of collision when performing vertical well clear recovery maneuvers was reduced as UAS vertical rate performance increased and sensor vertical rate errors decreased. A class of encounter is identified for which vertical-rate error had a large effect on the efficacy of horizontal maneuvers due to the difficulty of making the correct left/right turn decision: crossing conflict with intruder changing altitude. Overall, these results support logic that would allow vertical maneuvers when UAS vertical performance is sufficient to avoid the intruder, based on the intruder’s estimated vertical position and vertical rate, as well as the vertical rate error of the UAS’ sensor.

A Study of Conflict Resolution Timeliness and Impact of Horizontal Maneuver Parametric Settings

The tradeoff between efficiency and trajectory uncertainty is considered when evaluating how early to initiate a conflict resolution maneuver. Four fast-time simulations are conducted employing a well-established prototype conflict detection and resolution algorithm to quantify the fuel and delay penalties associated with deferring resolution maneuvers in order to increase confidence in the conflict prediction. Additionally, the effects of using finer resolution when selecting conflictresolution heading maneuvers are evaluated. Results indicate that early initiation of resolution maneuvers reduces airborne delay and fuel consumption, but only slightly. This finding suggests that it may be operationally desirable to forgo the modest delay and fuel benefits associated with earlier maneuvers in order to buy down the uncertainty that is inherent in trajectory predictions with longer time horizons.