27:
141:, which controls the pooling of blood in the lower limbs, but there is no suit yet capable of controlling a redout. In both cases, symptoms may be remedied immediately by easing pressure on the flight controls. Continued or heavy g-force will rapidly progress to
129:, or a reddening of the vision, which is the result of negative g-forces caused by performing an outside loop, that is by pushing the nose of the aircraft down. Redouts are potentially dangerous and can cause
118:
Recovery is usually rapid. A greyout can be readily reversed by lying down as the cardiovascular system does not need to work against gravity for blood to reach the brain.
125:
as when pulling up into a loop or a tight turn, which forces blood to the lower extremities of the body and lowers blood pressure in the brain. This is the reverse of a
145:(g-force induced Loss of Consciousness). Untrained individuals can withstand approximately 4g, while fighter pilots with g-suits are trained to perform 9g maneuvers.
148:
Surprisingly, even during a heavy greyout, where the visual system is severely impaired, pilots can still hear, feel, and speak. Complete greyout and
276:
237:
261:
Braithwaite MG, Durnford SJ, Crowley JS, Rosado NR, Albano JP. "Spatial disorientation in U.S. Army rotary-wing operations."
302:
Douglas H. Smith; David F. Meaney (October 2002), "Roller
Coasters, G Forces, and Brain Trauma: On the Wrong Track?",
38:
is a transient loss of vision characterized by a perceived dimming of light and color, sometimes accompanied by a
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72:
167:. Roller coasters are unlikely to have high enough negative g-forces to induce redouts, as most
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137:. Pilots of high performance aircraft can increase their resistance to greyouts by using a
8:
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riders. Many roller coasters put riders through positive g-forces, particularly in
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A greyout may be experienced by aircraft pilots pulling high positive
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50:(low brain oxygen level), often due to a loss of
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281:, British Aerobatic Association, archived from
201: – Medical symptom due to negative g-force
68:, even in mild form such as when drawing blood.
155:Another common occurrence of greyouts is in
57:Greyouts have a variety of possible causes:
274:
263:Aviation, Space, and Environmental Medicine
278:Physiological Effects of Positive G Forces
171:are designed to simulate weightlessness.
25:
236:Mike Leahy; Zeron Gibson (2005-08-25).
195: – Stage before syncope (fainting)
335:
240:. BBC/Open University. Archived from
183: – Illusionary dark gray color
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14:
364:
16:Visual dimming caused by hypoxia
46:or a blackout and is caused by
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268:
265:69(11):1031-7 (November 1998).
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229:
94:, paradoxically: self-induced
30:Simulated stages of a greyout.
1:
7:
174:
10:
369:
71:Standing up suddenly (see
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316:10.1089/08977150260337921
217:Whiteout (disambiguation)
212:Brownout (disambiguation)
207:Blackout (disambiguation)
40:loss of peripheral vision
222:
19:Not to be confused with
189: – Visual illusion
133:damage and hemorrhagic
75:), especially if sick,
73:orthostatic hypotension
42:. It is a precursor to
304:Journal of Neurotrauma
104:shallow water blackout
31:
152:are separate events.
150:loss of consciousness
29:
81:low blood pressure
79:, or experiencing
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310:(10): 1117–1120,
275:Eoin Harvey, MD,
98:, such as in the
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92:Hyperventilation
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238:"G-Force Diary"
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169:low-g elements
161:vertical loops
157:roller coaster
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52:blood pressure
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9:
6:
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3:
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343:Visual system
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285:on 2012-07-22
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244:on 2022-12-18
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100:fainting game
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353:Acceleration
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287:, retrieved
283:the original
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246:. Retrieved
242:the original
231:
154:
147:
120:
117:
113:Panic attack
109:Overexertion
56:
35:
33:
66:hypovolemia
337:Categories
289:2009-11-20
248:2009-11-20
193:Presyncope
96:hypocapnia
64:, such as
21:grayed out
348:Human eye
187:Phosphene
181:Eigengrau
324:12427321
175:See also
123:g-forces
77:hungover
44:fainting
165:helices
131:retinal
87:Fatigue
48:hypoxia
36:greyout
322:
199:Redout
139:g-suit
135:stroke
127:redout
102:or in
223:Notes
143:g-LOC
62:Shock
320:PMID
163:and
312:doi
339::
318:,
308:19
306:,
54:.
34:A
314::
251:.
106:.
83:.
23:.
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