The G Transition Effect Revisited - A Broader Flight Safety Threat than 'Push-Pull'


  1. Cheung, B.
  2. Bateman, W.A.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
The term 'Push-Pull Effect' (PPE), popularized in the last few years, has been used to describe observed reductions in G-tolerance during acceleration that was preceded by exposures to hypogravity (i.e. <+1Gz). The phenomenon can be easily interpreted as occurring only in classical 'bunt-then-pull' maneuvers. However, our review of previous research and operational evidence suggests a much broader spectrum of at-risk situations and adverse physiological and psychophysical effects. This complex phenomenon is not new, it was observed as early as 1953. It is suggested that the term 'G-transition effect' (GTE) more appropriately describes this phenomenon. Flight safety implications range from reductions in Gz-tolerance in a variety of scenarios to associations with disorientation and to confounding the results of centrifuge-based research (on which most current G-protection strategies were based). This report provides an overview of past and current research efforts supporting this broader concept of GTE. Of particular note, it seems that the organ of balance (i.e. the vestibular system, one of the components of the 'inner ear' that detects angular and linear acceleration) has significant influence on Gz-tolerance. TRUNCATED
G-protection;Spatial disorientation;Push-Pull Effect;+Gz;Hypogravity;Hypergravity;G transition;GTE (G-transition effect)
Report Number
DCIEM-TR-1999-085 — Technical Report
Date of publication
01 Sep 1999
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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