Pilot-in-the-Loop Evaluation of Tau-Theory-Based Rotorcraft Obstacle Avoidance Methodology and Visual Cueing System

Low situational awareness (SA) during low-altitude rotorcraft operations near terrain and obstacles increases flight risk by reducing the time available for pilot response. To address this problem, a Tau-theory-based obstacle avoidance methodology has been developed to support real-time trajectory adjustment and improve safety and efficiency in obstacle-dense and degraded visual environments (DVE). The method uses 3D conformal visual cueing presented on a head-up display (HUD) to support a heads-up, eyes-out interaction strategy. The present study provides a quantitative pilot-in-the-loop evaluation of this guidance framework. During the simulations, pilots interact with the visual cues in real time and assess the intuitiveness, responsiveness, and overall effectiveness of the system. The objective is to evaluate whether the framework can support safe obstacle avoidance, smooth maneuver transitions, and effective pilot-system interaction. Pilot feedback is also used to guide further refinement of the cueing system so that it remains intuitive, effective, and suitable for different operational scenarios. Overall, these pilot-in-the-loop evaluations serve as an intermediate validation step and demonstrate the potential of the system to improve situational awareness and flight safety during low-altitude operations in obstacle-rich environments.