G-LOC
Loss of consciousness due to G (Abbreviation: G-LOCCerebral hypoxia (stroke) is a term commonly used in aerospace physiology to describe loss of consciousness caused by excessive and sustained G-forces depriving the brain of blood, resulting in cerebral hypoxia. This condition is most commonly seen in high-performance fighter and acrobatic aircraft pilots and astronauts, but can also occur on some extreme amusement park rides.
G-LOC Incident Fatal accidents have occurred in high performance aircraft that can withstand high G forces for extended periods of time. High G training for pilots of high performance aircraft and spacecraft often involves ground-based training in G-LOC in specialized centrifuges, with some profiles exposing pilots to 9 G forces for extended periods of time.
However, there were only a few fighter pilots. Experienced a G-LOC incident.
Pull 9G
But what does it feel like to pull 9G?
Adam Deimudethe former U.S. Navy EA-18G Growler Pilot,explain On Quora;
“Oh, that hurts!!”
“From experience, at 220 pounds, 9 G’s is nearly a ton. That alone makes it difficult to maintain that gravitational force, but there are other things that make it difficult. 9G pulls a very temporary state.
“First, blood. Because the G-vector is down, blood is pulled there. With so much blood rushing in, your feet and legs swell up quickly, which is a problem because you have to think, but blood is being pulled from your brain. What you usually lose before losing consciousness is your peripheral vision (the photoreceptors in your peripheral vision are oxygen sensitive). That’s why we’re taught to do leg and abdominal clenching movements to get the blood pumping before the G’s start (the G-suit also provides about three times the G-resistance compared to resting). But at 9G, no matter how much G you clench, you can’t hold out for long. If you don’t stop clenching immediately, you’ll get (GLOC…G-induced unconsciousness).”
G cough and G measles
He continues:
Coughing. This is fun. If you hold it in for too long, it can damage some of the delicate tissue in your lungs and make you literally cough your lungs out. This doesn’t happen all the time, but if you’re in a long fight, be prepared for it.
“And finally, my favorite, G measles. This only happens in a centrifuge and it’s because I was exposed to speeds of 9G for about 15 seconds (which is a lot longer than it sounds). Some of my capillaries (in my case my arms) burst and you get spots on your skin from the burst capillaries. You look like you have measles, hence the name. And it itches like crazy! To make matters worse, the same thing that always happens when blood leaks from your veins or arteries happens: you get bruises. After going through the centrifuge, my arms were covered in bruises for about 4 days.
When I pull 9G, I feel like I have an elephant standing on my chest.
“So, to summarise, when you pull 9G it feels like an elephant is standing on your chest and it starts to do damage to your body very quickly. It’s reversible damage, but it’s damage nonetheless.”
Daymude concludes:
“Regarding G-tolerance: First off, I’m going to say that the values I give are based on a cardiovascularly healthy crew member. Just sitting in an ejection seat can typically tolerate 3G, meaning 3G should not cause drowsiness or other high G-conditioning symptoms. As I said above, wearing the G-suit gives you another 3G of tolerance. If you clench your legs and do what’s called a “hiccup” maneuver (actually pronounce it “hiccup”, pause on the k, and tighten your abs and chest), you get at most another 2G of tolerance. So, the most the average crew member can handle without fighting a losing battle is 8G. Very few people have that extra G-tolerance to safely hold a 9G pull.”
Photo credit: U.S. Navy, via Growler Air Show Team Instagram page
