The Effect of Aircrew Age on +Gz Tolerance as Measured in a Human-Use Centrifuge

Abstract

Abstract : Pilots of high performance aircraft are exposed to positive acceleration (+Gz). This type of acceleration displaces blood in the head to foot direction. As the pressure in the vessels of the lower body increases, the vessels dilate, and a major portion of the blood from the upper part of the body is translocated to these lower vessels. The pooling of blood in the lower extremities translates into reduced cardiac output provoking the cardiovascular system, mainly by the activation of baroreceptor reflexes, to maintain adequate blood flow to the central nervous system (CNS) and thereby maintain normal brain function (1, 3, 11). The physiologic symptoms of acceleration stress range from petechia hemorrhages (burst capillaries present in the limbs) to loss of vision and ultimately loss of consciousness with potential fatal consequences when it occurs in flight (1, 6, 11, 21). Mission effectiveness may also be affected by the stress in that the lack of adequate blood flow to the CNS leads to degraded motor and cognitive performance. This degradation may then lead to aircraft accidents and incidents commonly labeled as caused by pilot error. Hence, aircrew are routinely trained in the human-centrifuge to understand and better tolerate +Gz stress (10, 12, 18. 19).