Limiting g onset

[peekay]

The following is taken from an article in the British Medical Journal, Vol 286, May 1983. It was written by John Mills & Richard Harding of the RAF Institute of Aviation Medicine.

"In an unprotected relaxed subject unconsciousness usually occurs between +5 Gz and +6 Gz, the exact level depending on the rate of onset of G. If this is less than 2 G/s then the subject invariably experiences a sequence of visual symptoms before losing consciousness. At about +3 to +4 Gz the visual fields become darker, and at +0.5 to +1 Gz later peripheral vision is lost. From this condition of "greyout" the fields contract further to a state of “blackout”, when vision is lost completely. Hearing and mental orientation are, however, adequate for intelligent conversation until consciousness is finally lost about 0.5 Gz later. At higher rates of onset loss of consciousness is too rapid for these characteristic visual symptoms to develop."

The full article is available on the BMJ website but registration is required to view it.

This article seems to support the view that loss of conciousness can occur with little or no warning in high g manoeuvres with high onset rates. Unfortunately it doesn't provide any guidance on what the limit on g-onset rate should be.