Objective documentation and monitoring of human Gz tolerance

Close correlation between noninvasively recorded changes in blood content of the ear and simultaneous intra-arterial pressures at head level support the validity and utility of more widespread use of noninvasive, online monitoring and recording of circulatory changes at head level for objective measurements of G_z tolerance when unprotected and during use of anti-G suits alone and in conjunction with various self-protective respiratory and musculature-straining maneuvers. Extensive centrifuge and in-flight experiences during World War II verify that these objective hemodynamic techniques will expedite development and increase safety of high-G _z testing of improved methods for prevention of acceleration-induced loss of consciousness. The use of circulatory changes at head level to warn of impending loss of vision and/or consciousness for training purposes and as an activating signal for an automatic plane control system in potential ground impact situations is validated. The development of an unobtrusive within-the-ear photoelectric or ultrasound transducer, remotely controlled and received by a self-contained helmet or cockpit mounted system, would enhance pilot acceptability and the practicality of such a system