BACKGROUND: The risks posed by flight illusions impacting pilot spatial orientation have been determined as a safety concern from numerous past aviation accident investigations. Early demonstration of the adverse effects of flight illusions on spatial orientation would be desirable for all pilots, especially at the early training stages to deeply embed good practices for onset detection, flight correction, and response mitigation.METHOD: Simulated flights on a disorientation demonstrator were performed by 19 pilots for 3 conditions: no illusion, somatogyral illusion, and Coriolis illusion. An objective approach for assessing pilot performance degradation due to flight illusions can be done by using a defined flight profile: instrument landing system (ILS) flight trajectory during final instrument approach. Deviations to the standard ILS profile were recorded to measure and evaluate the influence of the demonstrated flight illusion on pilot performance.RESULTS: The results show the expectation that the smallest deviations from the ideal trajectory are caused by pilot tracking error (no illusion), and the greatest deviations are caused by the Coriolis illusion. Results demonstrated a statistically significant effect of illusions on performance. According to statements from pilots, training for flight illusion response is essential to complement training in aircraft regulations and aerodynamics.DISCUSSION: Measuring the influence of vestibular illusions on flight profile with a simulator allows assessment of individual differences and improvement of pilot performance under the conditions of no illusion, the somatogyral illusion, and the Coriolis illusion.Boril J, Smrz V, Blasch E, Lone M. Spatial disorientation impact on the precise approach in simulated flight. Aerosp Med Hum Perform. 2020; 91(10):767775.