Unmanned Aerial Vehicles (UAVs) are becoming increasingly common in both everyday life and professional contexts. The present study investigates the human factors that have to be considered in the adoption of UAVs in practice. In a one-factorial design, the impact of UAV indoor flights on human cognitive performance and well-being were analyzed. Fourty-eight participants were divided into an experimental (EG) and a control group (CG) and completed the Work Efficiency Test. In the EG, UAVs flew different path trajectories indoors behind a safety net. Additionally, flow experience, mental effort, and mental strain were measured. Results show that the EG performed marginally worse on the Work Efficiency Test than the CG and experienced less flow during task processing. Additional qualitative interviews showed that participants felt distracted by UAV noise and flight trajectories. Our results corroborate that the human factor cognitive performance should be considered in the implementation of UAV technology in the workplace.