GTIP Goals and Enabling Objectives l understand your personal type of light loss l learn when to utilize the anti-G hook l understand daily variations in relaxed G- tolerance l respect the 6 sec buffer period l appreciate the potential GLOC trap l understand the one-sided light loss that may occur in the check-six position
Terminal Objective G-TIP Be familiar with Gz acceleration forces, the causes and symptoms of (G-LOC), and the methods to improve G-tolerance.
Why pull Gs? l its fun l it builds character l so you can kill the other guy l so you dont get killed l actually only pull Gs to change direction
Anatomical/Physiological effects of G-Forces l Cardiovascular l Respiratory l Sensory l Cerebral
Cardiovascular Effects of +Gz: ÷ BP above the heart ù BP below the heart l blood pooling lower extremities ô CO and BV l 10 sec delay in reflex l Petechial hemorrhages
Cardiovascular system l your BP forces blood up to your brain l high Gs force the blood down away from your head l Hook maneuver is designed to raise the BP and keep blood flowing up to your brain –the muscle strain keeps blood from pooling in your legs or arms, trapping it in your chest –the hook closes your glottis so you can strain against it –the deep breath and strain raises pressure in the chest to squeeze blood up to your head
G-warm up maneuver, or G-awareness turn 1. press-to-test G-suit 2. pull about _ Gs for at least 10 sec no strain 3. OPTIONAL: gradually increase Gs without straining until you see some light loss determines your relaxed G-tolerance consider it might be a low-G day
The Cardiovascular Reflex, or Why do I do the G-warm up maneuver? l the carotid bodies in your neck sense a change in BP and initiate the cardiovascular reflex to maintain blood flow to your head l with increased Gs you see lower BP in your neck, and –your pulse increases –blood vessels throughout your body tighten up l this raises your BP and increases your relaxed G-tolerance
G-warm-up maneuver... l gives you about 3/4 G additional relaxed G- tolerance protection l but it takes 10-15 seconds to occur –might notice more light loss on first pull of the day l and lasts only about 10-15 minutes –so might consider doing G-warm-up close to the time that youll be needing the extra help
Push-Pull Effect l with sustained negative Gs l push over, or level inverted flight –BP rises in your head and your carotid bodies compensate by: l slowing your pulse, and l dilating your blood vessels –this lowers your BP in about 10-15 sec l but normally + Gs come on just as your BP is falling and you can GLOC at 3Gs ! l So avoid +Gs after sustained -Gs –wont occur unless -Gs last over 3-4 sec.
Petechia l polka-dot bruises in dependent areas where there is no counter-pressure l caused by high, sustained Gs l worse when you havent flown for awhile l like a bruise, looks worse the next day, but fades out in 3 - 5 days l are not contagious!
Respiratory Effects l Atelectasis l Hard to inhale
Atelectasis l chest tightness and feel short of breath after breathing 100% oxygen –release one side of oxygen mask l makes you cough l but is not because the oxygen is dry –oxygen, unlike air, is absorbed from your lungs so quickly that the air cells actually collapse and stick closed l worse after sustained Gs l the cough is the cure -- this re-inflates the air cells and relieves the unpleasant feeling
Hard to inhale l may feel like you cant get enough air in l due to physical forces compressing your chest –breathing is usually rather easy -- this isnt l you just have to work at it l hypoxia may contribute to decrease in performance, or increased likelihood of GLOC or ALOC l be efficient -- another reason not to work any harder than you have to!
Visual effects of +Gz: ô in retinal circulation ô in retinal perfusion l grayout or blackout ô visual field
Vision Loss 1. tunnel vision ==> in-from-the-sides 2. dimmer switch effect 3. splotches 4. curtain 5. combination/variations over time. Vision loss may be asymmetric.
One sided light loss l when check-6, normally inadvertently tilt our head a little, so one eye becomes higher than other l top eye loses light before lower eye l but we tend to use the good eye and ignore the light loss l the light loss in the top eye is the GLOC warning!
G-Excess Illusion l head tilt during a turn is misunderstood by the body, which thinks your head has tilted more than it really has l but since you know where your head is, you think that the plane experienced an uncommanded pitch-up l watch out during a sustained turn l dont go by your instruments!
Buffer Period l your brain functions normally without any blood flow for about 6 seconds, then simply shuts down! –probably a self-protective mechanism l answer to todays quiz question is: 6 sec
GLOC Trap l get in habit of waiting for light loss before we start to strain l but may have no light loss warning before GLOC above 6 Gs
Neurological Effects l Cognitive changes -- error making –some fatigue related, some ALOC l ALOC -- Almost GLOC –impairment but not LOC –typical almost lost it scenario l GLOC -- G induced loss of consciousness –LOC is all-or-none, but – G effects are a continuum
GLOC -- A Continuum fully conscious light loss blackout cognitive impairment = ALOC unconscious = GLOC
More about GLOC G-induced loss of consciousness 1. Absolute Incapacitation Period –classic LOC -- out cold –varies 1-18 sec, mean 12 sec l typical in-flight GLOC is short: 1-6 sec l as pilot lets go of the stick, plane goes to 1G –flailing is common l blood flow returns in watershed pattern
2. Relative Incapacitation Period –1-24 sec additional –lights are on, but no one is home l subject is upright, looks OK, but l incapable of thinking or responding –terminates abruptly with reintegration of mental functions and return to near normal capabilities –may lose SA
If you GLOC you may... l have some tingling or numbness l have some twitching or jerking l have a pleasant dream l not realize that you GLOCed! l be a little confused or disoriented l be aware that you have lost your hearing l feel a little off the rest of the day
Does Physical Training help G-tolerance? before we can answer, we must understand the terms: –Relaxed G-tolerance –Endurance G-tolerance –Straining G-tolerance
Relaxed G-Tolerance l the G level at which you have significant light loss without doing a straining maneuver. l relates to heart-to-eye distance –body shape –seat-back angle
l varies –from person to person –from day to day l same for women and men l 4 to 6 Gs for most people l obviously different with or without an anti-G suit l does not relate to physical training Relaxed G-Tolerance
your relaxed G tolerance is increased by l tilt-back seat –lowers shortens heart-to-eye distance –less than 1G improvement seen in F-16 l anti-G suit –onset delayed until after the Gs come on l recent G exposure -- the training effect
your relaxed G-tolerance is decreased by: l fatigue l alcohol l dehydration l illness l medication l layoff from G exposure
Straining G-tolerance l the highest G-level you can stand when doing your best straining maneuver l but is hard to measure and study l does relate to physical strength, and is improved by working out l physical training improves your ability to repeatedly strain without wearing out
Endurance G-tolerance l the time you can keep straining against varying G levels until you are exhausted l hard to measure, hence hard to use reliably in research l improved by both aerobic and anaerobic training!
Aerobic Training l was once thought to decrease your relaxed G-tolerance; probably not true l aerobic training actually improves your staying power by allowing rapid recovery from the straining –avoid extreme training -- keep your resting heart rate above 45
So, Physical Training... l does not affect your relaxed G-tolerance l does improve your strength and endurance G-tolerance –pays off on long, difficult engagements, and on frequent flights
Physical Training l So, train the muscles you strain –your goal is sustained, repeated straining with rapid recovery l include aerobic training l my personal view is that you are better served by understanding Gs, and doing what you have to effectively and efficiently
Neck Strength neck pain is #1 cause of down time for high-G aviators movement under Gs helmet, mask, NVGs, etc. Great Benefits come with neck strength better control (dont want to kiss your belly button!) less likely to be injured so, include neck strength training in your weight workout!
Neck Pain/Injury l leading cause of down time for high-G aviators l associated with high rate of G onset (snatching on the Gs) non-pilot cant anticipate G onset l head movement under Gs l additional head mounted equipment l good neck strength training minimizes injury potential
The Det Effect or, Whered my G-tolerance go? l Training Effect –G-tolerance increases when you fly Gs l Layoff Effect –and drops off again when you dont
Training Effect l relaxed G-tolerance will increase all by itself with frequent exposure to Gs –its not flight time, but G-time l can increase up to 2 Gs within a week –say usual relaxed G-tolerance is 5; G-suit makes it 6. So training effect can push it up to 8! You dont ever have to strain. l You get used to not having to strain
Engineering changes to improve G tolerance l tilt back seat (30 deg tilt) –gives < 1 G additional relaxed tolerance –standard seat is 13 deg; this raises your head and lets you see out better l anti-G suit –always lags the G onset l start your muscle strain before the Gs come on -- esp before high Gs –gives a 1G increase in relaxed G-tolerance
l positive pressure breathing with chest jerkin and Eagle anti-G suit l can sustain 8 Gs without straining! l can keep talking and breathing throughout high Gs l so increases your endurance too –less straining –better breathing l high Gs still suck, though.... Navy Combat Edge
Proper G suit fit... l G-suit helps you by doing some of the work l strain first, then slack off after the G-suit fills l fit should be snug, not tight l too loose just takes longer to fill up –while standing, should easily slip: l two fingers down by the thigh and calf, and l open hand down the front l release G-suit when you need to (spring, fall)
AGSM l M-1 classic grunt l L-1 glottis closed completely l Hook maneuver l I say its OK to use your own combination of leg strain/abdominal strain/hook maneuver as you need to. –Do what you have to do, but no more –understand what to do and why –know and respect the traps!
Hook maneuver 1. tighten all muscles before G onset Get a Jump on the Gs! above 6 2. deep breath, close glottis (say hook) 3. bear down and strain for 3 seconds strain harder for higher Gs; slack off at lower Gs 4. while maintaining continuous muscle strain, rapidly exchange full lung of air its hard to inhale under high Gs 5. work only as hard as you have to