Pilot’s perception of coordinated turns : relevance of long-arm centrifuge training

Human sensory systems, including the vestibular and visual systems, evolved for terrestrial locomotion under Earth’s gravity, and therefore tend to generate spatial illusions when confronted with the unfamiliar forces and motions of flight. Spatial disorientation arises when a pilot’s sensed attitude does not correspond to the aircraft’s true attitude, potentially leading to dangerous misinterpretations of flight maneuvers or instrument indications. During coordinated turns the semicircular canals initially detect roll motion, whereas the otolith organs, unable to distinguish gravity from centrifugally generated inertia, continue to signal an upright posture. The ensuing conflict fosters somatogravic illusions in which the perceived and the actual horizon diverge.

This thesis investigated spatial-orientation learning in dynamic flight-like environments, focusing on how pilots integrate vestibular cues with cognitive knowledge during aircraft and/or centrifuge turns. In all four studies, spatial orientation in the roll plane was quantified with the Subjective Visual Horizontal (SVH): in total darkness, participants rotated an illuminated line until it matched their perceived horizon, thereby yielding a direct measure of the perceived bank angle.

Study I validated a long-arm centrifuge as a proxy for coordinated flight turns. Eight experienced fighter pilots produced closely matching SVH settings in the centrifuge and in the aircraft, supporting the centrifuge’s utility for certain spatialorientation studies.

Study II examined how perceptual and cognitive factors contribute to SVH during simulated turns. Pearson correlation analyses revealed that accuracy was associated with each pilot’s knowledge of the G–bank-angle relationship, ability to sense sustained G-load, and ability to estimate and set verbally requested angles using a luminous line in darkness. Nevertheless, a systematic under-tilt and marked inter-individual differences remained.

Study III assessed a three-week, multisensory centrifuge-training program. Feedback that combined G-load exposure with explicit tilt information significantly improved perception at larger bank angles (≈ 60°) in both centrifuge and aircraft, although the benefit had faded two years later, underscoring the need for refresher training.

Study IV investigated whether increased G-awareness alone could improve rolltilt perception in nine flight cadets with no prior flight time. Five weeks of G-load exposure enhanced G-estimation but left roll-tilt perception unchanged, indicating that G-awareness by itself is insufficient.

Taken together, Studies III and IV show that multisensory feedback and directed attention are necessary if perceptual training is to enhance pilots’ awareness of roll attitude. Such training can complement—but never replace—the ironclad reliability of flight instruments.

Keywords: spatial disorientation; aviation; pilot; vestibular; cognition; spatial orientation learning; centrifuge training; subjective visual horizontal; perception

List of scientific articles

This thesis is based on the following four articles, which will be referred to by their Roman numerals:

I. Visual measures of perceived roll tilt in pilots during coordinated flight and gondola centrifugation. Arne Tribukait, Eddie Bergsten, Andreas Brink and Ola Eiken. Journal of Vestibular Research. 2023; 33(1): 1-19. https://doi.org/10.3233/ves-220016

II. Factors of significance for the ability of fighter pilots to visually indicate the magnitude of roll tilt during simulated turns in a centrifuge. Andreas Brink, Michail E. Keramidas, Arne Tribukait and Ola Eiken. Perception. 2024; 53(2): 75-92. https://doi.org/10.1177/03010066231209847

III. Influence of spatial orientation training in a centrifuge on the ability of fighter pilots to assess the bank angle during flight without visual references. Andreas Brink, Michail E. Keramidas, Eddie Bergsten and Ola Eiken. Journal of Neurophysiology. 2024; 1;132(3):710-721. https://doi.org/10.1152/jn.00129.2024

IV. A 5-week centrifuge-based G training with feedback on the magnitude of G force does not improve the perception of roll tilt during simulated coordinated turns. Michail E. Keramidas, Roger Kölegård, Andreas Brink and Ola Eiken. Journal of Neurophysiology. 2024, 1;132(5):1571-1576. https://doi.org/10.1152/jn.00311.2024