Search

When entering a coordinated flight turn without visual references, the perception of roll-angular displacement is determined by vestibular cues, and/or probably by assessment of the gravitoinertial (G) load (G magnitude) and its translation into the corresponding bank angle. Herein, we examined whether repeated exposures to hypergravity (G training) in a centrifuge, would advance, not only the ability to accurately assess the G load but also the capacity to detect or estimate the corresponding roll inclination of the centrifuge gondola. To this end, in nine men without piloting experience, the subjective estimation of G load and roll tilt were assessed, in complete darkness, during 5-min coordinated turns in the centrifuge, performed at 1.1 G (25° roll-tilt angle) and 2.0 G (60° roll tilt angle). These trials were conducted before and after 5 wk of G training {3 × 40-min sessions·wk−1; protocol: 20 × 1 min at G levels close to the individual relaxed G-level tolerance [range: ∼2.6 G (∼67°)–3.6 G (74°)], separated by 1-min intervals at idle speed (1.4 G)}, whereas continual feedback to the subjects was limited to the G load. As expected, G training improved subjects' capacity to assess G load, especially at 2.0 G (P = 0.006). The perception of roll tilt, however, was consistently underestimated (by ∼70%–80%), and not enhanced by G training (P ≥ 0.51). The present findings demonstrate that prolonged repeated G-induced roll-tilts in a centrifuge gondola, while external feedback is restricted to graviception, enhance the capacity to perceive G load, but fail to advance the ability to detect or consciously estimate the magnitude of roll-angular displacement during a coordinated turn. NEW & NOTEWORTHY: During a coordinated flight turn without external visual references, the pilot typically underestimates the aircraft bank angle, because unreliable information of roll tilt is conveyed by the vestibular system. The present results demonstrate that prolonged repeated gravitoinertial (G)-induced roll-tilts in a centrifuge gondola, while external feedback is restricted to graviception, enhance the capacity to perceive G load, but fail to advance the ability to consciously estimate the magnitude of roll angular displacement. [ABSTRACT FROM AUTHOR]

Without visual references, nonpilots exposed to coordinated flight turns underestimate the bank angle, because of discordant information of the roll-angular displacement from the otoliths, consistently signaling vertical position, versus the semicircular canals, enabling detection of the displacement. Pilots may also use their ability to perceive the G load and knowledge of the relation between load and angle to assess the bank angle. Our aim was to investigate whether the perception of bank angle can be improved by spatial orientation training in a centrifuge. Sixteen pilots/pilot students assessed their roll tilt, in complete darkness, during both real coordinated flight turns and gondola centrifugation, at roll tilts of 30° and 60°. The experiments were repeated after a 3-wk period, during which eight of the subjects performed nine training sessions in the centrifuge, comprising feedback on roll angle vs. G load, and on indicating requested angles. Before training, the subjects perceived in the aircraft and centrifuge, respectively: 37 (17)°, 38 (14)° during 60° turns and 19 (12)°, 20 (10)° during 30° turns. Training improved the perception of angle during the 60° [to 60 (7)°, 55 (10)°; P ≤ 0.04] but not the 30° [21 (10)°, 15 (9)°; P ≥ 0.30] turns; the improvement disappeared within 2 yr after training. Angle assessments did not change in the untrained group. The results suggest that it is possible to, in a centrifuge, train a pilot's ability to perceive large but not discrete-to-moderate roll-angular displacements. The transient training effect is attributable to improved capacity to perceive and translate G load into roll angle and/or to increased reliance on semicircular canal signals. NEW & NOTEWORTHY: Spatial disorientation is a major problem in aviation. When performing coordinated flight turns without external visual cues (e.g., flying in clouds or darkness), the pilot underestimates the aircraft bank angle because the vestibular system provides unreliable information of roll tilt. The present study demonstrates that it is possible to, in a long-arm centrifuge, train a pilot's ability to perceive large but not discrete-to-moderate roll-angular displacements. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pilots undergoing coordinated flight turns or centrifugation, whilst devoid of visual cues, exhibit substantial interindividual variation in their perception of roll tilt. The objectives of this study were to investigate whether, and to what extent, specific perceptual and cognitive abilities can account for this inter-individual variability. METHODS: Twelve experienced fixed-wing pilots were subjected to centrifuge tests on two separate occasions, with a six-month interval between them. The subjective visual horizon (SVH) was measured in darkness using an adjustable luminous line during three 6-minute centrifuge runs, each involving different roll tilts: 25° (1.1 G), 56° (1.8 G), and 66° (2.5 G). Initial and final SVH settings were recorded for each G plateau. During the second occasion, the SVH settings were temporarily interrupted at each plateau (visual distraction task). In addition, verbal estimations of experienced G loads were provided by the pilots. After the centrifuge tests, 1-g environment, the pilots were questioned about the relationship between G load and roll tilt, and they were asked to adjust the luminous line so that its slope corresponded with specified angles. RESULTS: The pilots underestimated their roll tilt throughout each G plateau, average SVH being 4° to 28° less than the actual roll angle at the different G loads. The visual distraction task did not affect the SVH settings. A multiple regression analysis indicated that the chain of tested capacities - perception of G load, knowledge of relation between G load and bank angle, accuracy when indicating angles in 1 g - significantly contributed to the SVH. DISCUSSION: Thus, the tested chain of skills appears to influence the pilots' ability to assess the degree of roll tilt during simulated coordinated flight turns. Notwithstanding, SVH was typically markedly smaller than predictions based on the specific abilities. Presumably, SVH is also dependent on subconscious processing, linking the sensation of bodily weight to a visually imagined horizon. Learning Objectives 1. Participants will gain insight into the role of the vestibular system in pilots' perception of roll tilt during coordinated flight turns and centrifugation, and how it interfaces with cognitive processes, shedding light on the complexities of pilot perception. 2. Participants will understand the challenges posed by the nonlinear relationship between G load and bank angle perception, and how the brain's reliance on otolith information for spatial orientation can affect pilots' ability to accurately estimate roll tilt, highlighting the need for potential training regimens to improve this capability. [ABSTRACT FROM AUTHOR]