Impact of + Gz Acceleration Stress on Accuracy of Colour-coded Number Recognition in Pilots

Abstract

Colour vision, particularly in modern so-called glass cockpits, plays a crucial role in ensuring flight safety. In this study, we investigated how exposure to high G-forces affects visual perception and performance in colour-coded number recognition tasks among pilots. Ten men fast-jet pilots (ages 28–45 years) were tested in a human centrifuge while reading digitalised plates from an Ishihara test displayed on a screen. Generated accelerations ranged from + 3 to + 7 G_z, increasing in nine intervals of 0.5 G with a rapid onset rate of 1 G·s⁻¹. During each 15-s acceleration plateau, three colour plates were displayed. Colour vision in the blue-yellow and red-green axes was tested in two separate sessions. The accuracy of predicting the correct reading of the colour plates based on the + G_z level was 81% for the blue-yellow axis and 76% for the red-green axis. The first impairment in colour perception occurred at + 5.5 Gz and affected both colour axes. The reading time is slightly affected by increasing G levels, with no apparent relationship to colour processing. Sequential changes in colour perception were observed. A high sensitivity threshold of the Ishihara test likely hindered the detection of subtle changes in colour vision among pilots under high G-forces. Despite its limitations, our study provides useful insights for future research on colour vision under high-G conditions.