1. Introduction
Extreme time pressure, task criticality, and mission complexity cause stress and increase a military pilot’s workload in a manner that impact aviation safety directly ( Huttunen et al., 2011). Stress is the physical manifestation of a body reacting to change requiring a physical, mental, or emotional adjustment or response. Acceler-ation (G) is a major physical stress associated with combat flying ( Balldin, 2002). Gravitational force (G-force) is the measurement of a force acting on an object, with acceleration proportional to multiples of G, acting in the opposing direction from which the object receives the force. The rapid acceleration of a jet fighter generates G-forces. A G-force from six to nine Gs is usually considered high. A high G-environment can be extremely dangerous, particularly for fighter pilots unfamiliar with the physical effects of continuous exposure to these forces. Inexperi-enced pilots cannot understand completely how to avoid or compensate for the dangerous consequences of high gravitational exposure ( Gillingham and Fosdick, 1988). Blood flow in a human body subject to high positive G (>þ6 G) can barely reach the brain,
increase or alleviate the perceived stress undergone by trainees when partaking in centrifuge training.