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My first blackout

VNugget

suck squeeze bang blow
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[font=Verdana, Arial, Helvetica, sans-serif]So today I had my 5th or so acro lesson, and at the end, when we were about to head home, I asked my CFI if I could fly a steep spiral and pull and sustain max G to see if I could grey or black out. It's just something that I had never experienced, and was really curious about. So he said sure. This was in a Citabria 7KCAB, by the way.

With a 90 degree bank and a hefty nose-down attitude and pulling hard, I may have hit 4 Gs, but the most I could sustain was probably around 3, and nothing happened. Also, the straining from pulling the stick may have been enough to keep my vision intact. I didn't really get any symptoms.

So we decided that he'd fly the next time, while I sat there completely relaxed. That time actually worked. He had the nose way down there, and we managed to sustain 4 Gs. I felt every part of my body sag, and after 4 or 5 seconds, my vision got all fuzzy and bubbly, but I can't really say that I lost any of the color. Maybe a little bit. A bit later, I finally started to lose my vision around the outside, and the grey zone squeezed in farther and farther toward the middle, until the visible circle finally shank to nothing, like the end of a Looney Tunes cartoon. Next thing, I decided to tighten my legs and abdomen to squeeze the blood back up to my head, but just as I started, my CFI unloaded the plane so I didn't get to see the effect.

I asked him to do it one more time, and this time he sustained it long enough for me to completely lose my vision again, and then squeeze it back in. It was neat.

Everything, including the blackout and the straining maneuver, went pretty much exactly as I read about it and expected, except that the "curtain" was grey, and not black. I suppose I'd have to wait a little longer (and/or pull some more Gs) for it to go all the way black. Although I'm pretty sure it's accurate to say that I did black out, since all my vision was gone, and greyout just refers to the loss of color.

It was a pretty cool experience, both as a learning experience and as fulfilling a long-held curiousity.
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Fury220

Resident T-38A/C FAIP
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I don't think GLOC is fun. G's are fun, GLOC is deadly.
 

Occam's Razor

Risible...ALWAYS risible
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I got to put on my dress blues twice to bury comrades killed by GLOC.

The "tunnel" is probably a good thing for every pilot to experience, if only to demonstrate the danger.

Stalls, spins, GLOC, and flying as my F/O.

All have an element of real-world danger.
 

siucavflight

Back from the forsaken
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GravityHater said:
What is the max g limit for a citabria, anyway?
3 G's.:D
 

RockyMnt1

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Be sure to report this loss of conciousness on your next medical!! Then the fun will really begin......
 

Flying Illini

Hit me Peter!
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Can someone explain the difference in GLOC and blackout? Can GLOC kill him or does it only kill people who experience it in single-pilot aircraft?
 

ms6073

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G-induced Loss of Consciousness (G-LOC) does not kill pilots - unless the pilot has some physiological deficiency that may cause an aneurysm or heart attack. G-LOC interferes with a pilots ability to make inputs to the flight controls and can create a momentary loss of situational awareness - not somewhere you want to be when traveling at high rates of speed (any speed actually) and close to the ground. When the pilot is experiencing G-LOC, the risk of CFIT (controlled flight into terrain) or an unrecoverable departure from controlled flight become major factors.
 
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EagleRJ

Are we there yet?
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It sounds like you never lost consciousness. When you begin to black out, your vision will go before the rest of your brain, so at a certain point you will still be conscious even though you cannot see. When you wake up from total GLOC, it feels like you have been asleep for hours, even though it was probably only a few seconds.

Using the Energy Straining Maneuver (tightening every muscle in your body below the chest) works best before you expose yourself to high G-forces, if you are trying to remain conscious. It's especially important in civil aerobatic aircraft, since you don't have a G-suit or semi-reclining seat to help you out.

GLOC doesn't usually kill people in GA acro aircraft, since the aircraft will unload the second you release the stick, and normally won't depart before you wake up. As always, there are exceptions (Vertical-8 performed at low altitude).
 

Immelman

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Max load factor for a 7GCAA is +5.5G... KCAB is probably the same.

I have experienced the same (under instruction from an AF pilot with plenty of t-38 fun time) at about 4.5 Gs.. we never wanted to really go over that to not approach the airframe's max load.. I agree that it is good practice; just be sure whoever is instructing can handle the G-load!!! I found that flying regualar aerobatics, a tolerance of sorts (at least for slightly longer periods of time at those loads) were built up.
 

Occam's Razor

Risible...ALWAYS risible
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ms6073 wrote: "When the pilot is experiencing G-LOC, the risk of CFIT (controlled flight into terrain) or an unrecoverable departure from controlled flight become major factors."

Not to quibble...but it ain't "controlled" flight into terrain if the carbon-based "control unit" (spelled "P-I-L-O-T") isn't controlling. When the pilot goes to sleep during a high-G maneuver, which got us to the GLOC portion of our flight, the whole control thing ends.
 
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