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  • Title: Greyout, blackout, and G-loss of consciousness in the Brazilian Air Force: a 1991-92 survey.
    Author: Alvim KM.
    Journal: Aviat Space Environ Med; 1995 Jul; 66(7):675-7. PubMed ID: 7575318.
    Abstract:
    A national survey has been performed with high and medium performance aircraft pilots on the incidence of symptoms due to +Gz acceleration, in order to make up a human centrifuge physiological training profile directed to the needs of the Brazilian Air Force pilots. Anonymous questionnaires were sent to Flight Squadrons of F-5, AMX, Mirage F-103, Xavante AT-26, and Tucano T-27. They consisted of inquiries about the occurrence of visual symptoms and/or loss of consciousness during +Gz (G-LOC) maneuvers, and post-G-LOC symptoms. Some 193 pilots answered the questionnaire: 23 (11.92%) reported greyout and/or loss of peripheral vision; 40 (20.72%) reported blackout; 20 (10.36%) reported G-LOC. Those who reported LOC also reported post-G-LOC symptoms (100%), 16 (80%) being gradual and 4 (20%) instantaneous. Incidence of G-LOC did not depend upon the type of aircraft flown (p > 0.05). Considering the pilots who reported G-LOC, 80% were preceded by blackout, which could allow them to relieve +Gz load before they would reach their endpoint for the occurrence of G-LOC. For these reasons we recommend intensive human centrifuge training periodically, similar to the hypoxia-recognition test in the hypobaric chamber, not only for high performance aircraft pilots but for any pilot who can perform aerobatics (thus exposing himself to the adverse effects of "pulling G"). This will allow each pilot to recognize his consciousness endpoint when undergoing +Gz maneuvers, in a controlled and safe environment.
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