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Aerospace Medicine Technical Reports
FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute
Report No:DOT/FAA/AM-23/6
Title and Subtitle: Cerebral Blood Flow Based Computer Modeling of Gz-Induced Effects
Report Date: January 24, 2023
Authors: K. Copeland; J. E. Whinnery (Ret.)
Abstract: Introduction: There is continued interest in acceleration (G) effects in civil aviation, as G-induced loss of consciousness (G-LOC), impaired consciousness, and visual effects play a role in aerobatic, agricultural, and military aviation accidents. Methods: A software model (the Civil Aerospace Medical Institute G-Effects Model [CGEM]) based on physical and physiological variables related to inflight tissue resupply, using oxygen flow as a proxy for supply availability, was developed to evaluate risk of G-LOC and related phenomena in aeronauts. Aeronauts were modeled using several parameters, including sex, cardiovascular fitness, and other common modifiers such as G-suits, positive pressure breathing gear, anti-G straining and other muscle-tensing. The software was validated by comparison with experimental data from the peer-reviewed literature. Results: CGEM predicted physiological effects of Gz exposure accurately, particularly for rapid onset rates. Predicted times to G-LOC and absolute incapacitation periods were consistently within one standard deviation of pooled results obtained during centrifuge experiments using USN and USAF pilots. Predictions of G tolerance based on visual effects onset also compared well with published data, as did evaluation of symptoms expected during a difficult aerobatic maneuver. Discussion: CGEM is a new tool for civil and military aviation. Rather than providing a simple G tolerance number, through proper selection of parameters flight surgeons, pilots, and accident investigators can gain insight into changes in risk from factors such fatigue, medications, dehydration, and anti-G countermeasures used.
Key Words: acceleration, aerobatics, G-LOC, G-tolerance, modeling
No. of Pages: 18
Aerospace Medicine Technical Reports
FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute
Report No:DOT/FAA/AM-23/5
Title and Subtitle:CGEM User’s Guide
Report Date: May 2021
Authors: Copeland, K.
Abstract: This report is a guide to the use of the Civil Aerospace Medical Institute (CAMI) G Effects Model (CGEM) software. The software models effects of extreme Gz accelerations, including visual symptoms, G-LOC, and return to consciousness following G-LOC. The software accommodates Gz acceleration profiles experienced by most civilian and military pilots and also reproduces historical centrifuge experiments. Effects such as dehydration and fatigue are readily accommodated through changes in physiological parameters. Future planned developments include extending the model to include monitoring additional brain centers, anti-G equipment failure, an improved lung function model, direct inclusion of a library of acceleration profiles for standard maneuvers used in aerobatics, and a more user-friendly means of inputting effects of pilot dehydration and fatigue beyond adjusting the current input parameters.
Key Words: G-LOC, blackout, aerobatics, peripheral light loss, G tolerance, acceleration
No. of Pages: 29