G-LOC
G-induced Loss Of Consciousness (G-LOC) refers to a state of unconsciousness resulting from high and sustained g-forces that deplete blood from the brain, leading to reduced oxygen supply to the brain. This condition predominantly impacts pilots flying high-performance fighter and aerobatic aircraft or astronauts, but it can also occur on certain extreme amusement park rides.
G-LOC incidents have resulted in deadly accidents involving high-performance aircraft that can endure high g forces for prolonged periods. Training for pilots operating high-performance aircraft or spacecraft often involves ground exercises for G-LOC in specialized centrifuges, with certain training profiles subjecting pilots to 9 Gs for an extended duration.
Nevertheless, only a few fighter pilots have experienced G-LOC incidents.
How high Gs over many years damage a fighter pilot’s body
But do repeated exposures to high Gs over many years have long-term negative effects on a fighter pilot’s body?
John Chesire, former US Navy F-4 Phantom II and F-14 Tomcat pilot, explains on Quora;
‘I had a CAT Scan or an MRI a few years ago for something else. Part of it showed a lot of degenerative arthritis and damaged discs in my neck.
‘The doctor reviewing the results said, “Whatever did you do to your neck?” I responded, “I once was a fighter pilot.” He replied, “Well, that explains it!”
‘Of course, little did he know I would also snap my neck at every lovely young lady in a short skirt who passed by me back then, so who knows the cause.
‘I do not know of other fighter guys having the same problem, but I also have never asked. I do remember one flight where I twisted my neck under high Gs and pinched a nerve in my neck. I was stunned and momentarily incapacitated. My RIO was screaming as we were nose down and almost supersonic, asking me what was going on. He almost ejected. We still talk about that decades later.
‘I have mild neck pain to this day, although I can live with it. I don’t know if it is the result of twisting and turning my neck around violently while pulling 6-Gs, or if it was the time, I dove into the Platte River in Nebraska and hit a submerged sandbar.’
Chesire concludes:
‘If I could do it all over again, would I do it? Yes, to being a fighter pilot; no to diving in the Platte River.’
U.S. Navy photo by Photographer’s Mate 2nd Class Daniel J. McLain
