Guidelines for a research and development (R&D) program for high sustained G.
This article is a contribution to the workshop on "Operational Requirements in the Prevention of G-Induced Loss of Consciousness (G-LOC) in High Performance Aircraft"; it focuses on the "operational" side of the requirements to prevent G-LOC.  There are two types of requirements for prevention of G-LOC; a) pre-G-LOC detection devices that monitor physiologic changes of the pilot before G-LOC occurs, and b) the more generic personal G protection systems that increase G tolerance.  Recently there have been major advances in G-protection research and development (R&D) systems (soon to become operational) that significantly improve G-level and G-duration tolerances.  We do not know the extent of the impact of these new systems on G-LOC, but it could be substantial.  These near-term operational anti-G systems are:  1.  Positive pressure breathing (PPB) systems assisted by chest counterpressure that are activated by an increase in G levels; i.e., the higher G level, the greater the pressures applied to the aircrew member (Morgan et al., 1992).  This PPB system is known as PBG.  PBG has been flight tested with the standard operational anti-G suit.  This test program known as Combat Edge significantly reduces pilot fatigue and extends G-duration tolerance.  In limited operational testing of F-16 and F-15 aircraft, PBG has received substantial pilot acceptance.  2.  An improved anti-G suit that provides uniform pressure of the lower body that includes the operational anti-G suit abdominal bladder.  This new anti-G suit concept increases both G-level and G-duration tolerances (Krutz et al., 1990; Morgan et al., 1992).  Flight tested as the Advanced Tactical Anti-G Suit (ATAGS), it is comfortable and preferred by pilots over the standard operational anti-G suit.  3.  The combination of Combat Edge and ATAGS, the most advanced anti-G system in the final stages of development (Morgan et al., 1992).  This anti-G equipment has been tested in the laboratory on the centrifuge.  Experimental subjects are able to tolerate 8 to 9G "relaxed" or with a minimal anti-G straining maneuver (AGSM) (Morgan, 1992).  Accleration scientists believe that once these systems become operational on high performance aircraft that the incidence of G-LOC will be significantly reduced, particularly G-LOC associated with fatigue.
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Armstrong Laboratory, Brooks Air Force Base, Texas 78235-5118, USA.
D000337:Aerospace Medicine; D001359:Aviation / Q000295:instrumentation; D005081:Exercise Therapy; D005676:Gravity Suits; D006801:Humans; D018471:Hypergravity / Q000009:adverse effects*; D011175:Positive-Pressure Respiration; D012106:Research; D013575:Syncope / Q000209:etiology / Q000517:prevention & control*; D014474:Unconsciousness / Q000209:etiology / Q000517:prevention & control