Eli5, how fighter jet pilots do not crash when they become unconscious due to high g force?
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Two ways:
– The flight suits they wear are specifically designed to help them combat g-force. They push on the extremities so it is tougher for blood to get there, keeping it near the core so the brain continues to get enough oxygen.
– There is an anti-g technique they use, where they contract certain muscles to help push blood toward the brain.
A combination of these two techniques allows them to consistently withstand up to 9 gs.
Sometimes they do: [https://www.aopa.org/training-and-safety/online-learning/early-analysis/n129mm](https://www.aopa.org/training-and-safety/online-learning/early-analysis/n129mm)
The short answer is altitude, because with that comes time, usually. When pilot blacks out, generally they relax and whatever control input that was causing the high G loading is no longer there, so they wake up, hopefully with time to resume control and prevent bad things happening.
Most modern jets will auto-recover. It’s called an Auto-GCAS (Ground Collision Avoidance System). It will basically auto-level the plane if it detects an impending crash. There are videos of F-16 pilots that blacked out and the GCAS recovering the aircraft.
They used to crash a whole lot but sometime after Fly-by-wire was introduced someone rigged the autopilot to the radar altimeter so the plane levels out when it gets too close to the ground. It’s not perfect but it’s often just enough to keep the plane flying long enough for the pilot to wake up.
Some good answers here, but people are still missing a few important aspects.
First is that a pilot going unconscious is a VERY BAD THING. This is not normal. Fighter pilots do not typically pull enough G’s to fall unconscious. They intentionally go to the limit and not any further. So unconscious pilots are a fairly rare thing.
Second, when a pilot passes out from too many G’s, they recover very quickly. Typically within a few seconds after the G forces have been lowered. [Here](https://www.popsci.com/story/technology/f-15-incident/) is a story of a trainee who passed out during a training flight from pulling too many G’s, he recovered in 11 seconds.
So unconscious pilots (from G forces) are very rare, and when it does happen they regain consciousness quickly.
Well, a lot of time they DO crash when the pilot goes unconscious from the G load. So, the emphasis is on preventing GLOC.
Some planes have auto-GCAS that flies the plane away from the ground when the pilot loses control, but it is possible that the airplane is out of the envelope of the system and the plane still crashes.
They can crash if they lose consciousness. That’s why they train so hard building up tolerance and learning how close to the limit they can go without crossing it.
Short answer is still happens from time to time especially on older airplanes.
Others have special computer programs to automatically level the jet so it doesn’t head straight into the ground if a pilot passes out.
They generally speaking *don’t* become unconscious during high force maneuvers. If it does happen that’s a serious event and that flight is over.
You hope you have enough time and altitude to wake up and recover before the dirt, or as others have alluded to, the auto-recovery software kicks in to give you the extra time needed to wake up.
Tons of prevention and safety measures.
First, specific training for knowing a pilot’s limit until LOS. There are many ways of applying high g forces in a pilot without needing to risk the pilot’s safety and the plane. Use a machine that mimicks the g forces applied and periodically make the pilot use it so that both the pilot and its superiors know the limit. And the pilot will actively avoid entering such g force zone.
Second, neck training, just like professional driving pilots, is mandatory. This is necessary to handle lower g that make most humans unable to hold their neck still ; being unable to hold the neck is one of the ways of getting loss of consciousness (LOS), as misposition of the neck constrics some structures.
Third, brain circulation physiology. People that get LOS when they get a neck hold (for example, MMA fighters) usually regain consciousness in seconds after the neck hold is stopped. So when a fighter pilot gets LOS due to high g force, being unable to continue to execute the maneuver reduces the g forces being applied and the pilot will regain consciousness in seconds as well.
Fourth, body type is actively chosen by the military and the pilot is subject to intense cardio routine training. Return of consciousness is faster the lower the muscle mass and the better shape the heart is. The 6’6 240 lbs guy that likely uses steroids and hates cardio training? Awful for being a fighter pilot. The average pilot is likely to be of average height and weight (if not lower than average as this allows for a smaller aircraft) and gets a ton of cardio training. The average pilot is likely a guy that is so physically unremarkable that the general public would never suspect that the guy is a military officer. Yuri Gagarin, for example, was 1.57m tall.
Fifth, automode. Fighter jets have auto recover mode that detects when the pilot has gone through LOS and maneuvers itself in a way that prevents a crash.
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