Small remotely piloted aircraft system (sRPAS) to ground human head impact could cause injuries to the public. Skull fractures and brain injuries have been observed in sRPAS-related impacts, which varied in angles, locations and velocities. This study developed a representative quadcopter sRPAS finite element model and incorporated it with THUMS ver 4.02 50th percentile male and 5th percentile small female models to simulate sRPAS to human head impacts. The simulations were validated with cadaver experiments. The common injury metrics such as head injury criteria (HIC) and brain injury criterion (BrIC) were correlated with head injury-related responses such as skull von Mises stress, brain strain, and strainbased cumulative strain damage measure (CSDM). HIC showed moderate to strong correlations with skull stress. BrIC correlated with brain strains but at weaker correlations compared to the correlations in other impact scenarios such as sports- or auto-related collisions, demanding further investigation. The most damaging impact directions were identified as rear 0 degree for inducing high skull von Mises stress and frontal 58 degree and rear 58 degree for inducing high brain strain. Lastly, this study compared the head and brain responses between different sexes under sRPAS impacts and highlighted the higher risks for small female compared to average male.