‘Everything quickly went from blue to gray to black. Like really quick. Had I continued to haul back on the stick, I probably would have taken a nap, but I had a window where my eyes weren’t working at all, but my brain was fully aware of what was going on,’ Lynn Taylor, former A-10 Pilot.
G-induced Loss Of Consciousness (abbreviated as G-LOC) is a term generally used in aerospace physiology to describe a loss of consciousness occurring from excessive and sustained g-forces draining blood away from the brain causing cerebral hypoxia. The condition is most likely to affect pilots of high performance fighter and aerobatic aircraft or astronauts but is possible on some extreme amusement park rides. G-LOC incidents have caused fatal accidents in high performance aircraft capable of sustaining high g for extended periods. High-G training for pilots of high performance aircraft or spacecraft often includes ground training for G-LOC in special centrifuges, with some profiles exposing pilots to 9 Gs for a sustained period.
But during a high G manoeuvre, when you have to fight to not black out, can you still think clearly? Does blood draining from your head seriously impede you?
‘There I was…
‘I was still fairly new to the flying gig, maybe midway through the first phase of pilot training, learning aerobatics in the 6,000 pound dog whistle [Cessna T-37],’ remembers Lynn Taylor, A-10 Pilot, Joint Firepower Course Instructor, Air Liaison Officer, remembers on Quora.
‘The maneuver was supposed to be a simple loop. Steady pull straight back on the stick until the world is upside down, then keep everything aligned properly on the way down as you put the Earth back the way you found it.
‘My instructor in the seat next to me knew our planned profile, and I checked everything in preparation for the maneuver. Altitude good. Airspeed good. Airspace good. G-strain maneuver on. And… pull.’
‘I realized I had a problem as my nose approached the vertical. Everything quickly went from blue to gray to black. Like really quick. Had I continued to haul back on the stick, I probably would have taken a nap, but I had a window where my eyes weren’t working at all, but my brain was fully aware of what was going on.
‘I relaxed back stick pressure and let the jet coast (I was nose up with a lot of air below me). My vision returned in short order and I transitioned into a completely different maneuver.
‘“What are you doing?” asked my instructor.
‘“Nose high recovery,” I said, as nonchalant as a noob fighter pilot in training could be.
‘“Why?” “I couldn’t see anything.” ‘“…Oh.”
‘I executed a textbook nose high recovery, and got set up for the loop again.
‘I was better on my G-strain the second time around. And every time after that. It was a good lesson to learn early on.’
‘So, it’s possible to G-LOC with little to no warning if the G-onset is quick enough and large enough. But it is also possible to retain consciousness and function even during blackout. It really varies by situation, by pilot, and even depends on transient factors like how well rested and hydrated you are. Some days you’re a G-monster, and others… not so much.
‘But if you have a good anti-G strain maneuver going, and you’re in good shape, you can sustain a solid pull and think clearly for quite some time. The trick is keeping blood in the brain pan. Do that, and you’ll be A-okay.’
Photo credit: U.S. Air Force and screenshot from YouTube Video