Evaluation of a Trajectory Prediction Algorithm Within a Ground Collision Avoidance System

While transport category aircraft have maintained an excellent safety record for over 20 years, small general aviation aircraft pose significantly higher risks. To address this, the National Aeronautics and Space Administration (NASA) and the Federal Aviation Administration (FAA) are funding research to adapt technologies originally developed for military fighter aircraft to enhance safety in small general aviation aircraft. One promising technology is the Ground Collision Avoidance System (GCAS). This paper focuses on evaluating a critical component of GCAS, the Trajectory Prediction Algorithm (TPA), for implementation in general aviation airplanes. The TPA approximates the aircraft's future trajectory, which is cross-referenced with terrain data to assess the need for ground avoidance maneuvers.The paper presents a detailed description of a comprehensive simulation-based evaluation tool-set designed for the verification of the TPA. Specifically, it provides techniques and analysis of the NASA "EVAA" TPA, which has been tuned for a 1982 Cessna 172P aircraft. The results of over 600 individual test cases, considering varied initial states and environmental conditions, are presented. These tests reveal the strengths of NASA's TPA and areas where further tuning could be beneficial. The findings highlight the effectiveness of simulation-based evaluation tools in the development and verification of a GCAS for small general aviation aircraft.