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The mathematical models developed in this article predict the following human G-level tolerances: 1 ) rapid onset relaxed (ROR); 2) gradual onset relaxed (GOR); and, 3) straining-rapid onset. Included in the model are specific functions of: 1) anti-G suit; 2) positive pressure breathing (PBG); 3) baroreceptor reflex; 4) handgrip reflex; 5) anti-G straining maneuver (AGSM) increasing intrathoracic pressures (Pi); 6) leg elevation; and, 7) reclining seatback angles ≤ 55° These functions are based on sound physiologic principles. Also discussed in the development of this model, but not included in the models, were: 1) isometric muscle contraction reflex; 2) Qigong (Q-G) maneuver; and, 3) straining GOR tolerances. The straining GOR tolerance profile was calculated to be a measure of G-duration tolerance and not G-level tolerance. A maximum Pi of 125 mm Hg from the AGSM was used in these models that could be augmented with PBG to 185 mm Hg. G-level tolerance predictions using this model were validated with published data.

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From 1988 to 1995, there were five reported cases of hemochromatosis among U.S. Army aviators. Three of the five are presented and discussed. The cases of hereditary hemochromatosis were discovered during unrelated work-ups or from investigation of a positive family history, and not by routine flying duty medical examinations. Recent studies show a prevalence of 5 per 1000 in the general population. This study shows the incidence among Army aviators is 0.296 per 1,000 aviator-years of observation. It is possible that there are cases presently undiagnosed in the Army aviation community. Without screening measures in place, the Army Aviation Branch has greater difficulty diagnosing and treating hereditary hemochromatosis. Heightened awareness and a high clinical index of suspicion are necessary to identify affected patients. Early detection and treatment is essential to prevent long-term end organ damage from iron deposition.