[Effect of rotation and vibration on orientation in man in relation to the gravitational vertical].

The man's ability to get oriented in relation to the gravitational vector was investigated. The test subjects were exposed either to rotation in 1 m arm centrifuge or tilting in a chair. They were simultaneously exposed to total-body vertical vibration of 20 Hz. As the exposure continued, the ratio of the perceived vertical (in the absence of visual keys) and the apparent body position changed significantly. It is concluded that the tests used to evaluate the pilot ability for spatial orientation should include evaluations of the subjective vertical and body position relative to the gravitational vector. The tests should be performed during exposures to simulated dynamic flight factors.