Aerospace Physiologist MSC Symposium LT Yniguez MCAS, Cherry PT G-TOLERANCEIMPROVEMENTPROGRAM.
Transcript of Aerospace Physiologist MSC Symposium LT Yniguez MCAS, Cherry PT G-TOLERANCEIMPROVEMENTPROGRAM.
Aerospace PhysiologistAerospace Physiologist
MSC SymposiumMSC Symposium
LT Yniguez LT Yniguez
MCAS, Cherry PTMCAS, Cherry PT
G-TOLERANCE G-TOLERANCE IMPROVEMENT IMPROVEMENT PROGRAMPROGRAM
GTIP Goals andEnabling Objectives
understand your personal type of light loss
learn when to utilize the anti-G ‘hook’ understand daily variations in relaxed G-
tolerance respect the 6 sec “buffer period” appreciate the potential “GLOC trap” understand the one-sided light loss that
may occur in the check-six position
Terminal ObjectiveG-TIP
Be familiar with Gz acceleration forces, the causes and
symptoms of (G-LOC), and the methods to
improve G-tolerance.
G-LOC A DEADLY THREAT
AIRCRAFT NO. G’sFA-18 8 5.5-8.0F-14 1 4.0AV-8B 1 5.5EA-6B 3 3.0-4.0S-3 1 3.0T-2 3 3.5T-34 35 1.5-9.0
Why pull Gs?
it’s fun it builds character so you can kill the other guy so you don’t get killed actually only pull Gs to change
direction
Anatomical/Physiological effects of
G-Forces
Cardiovascular Respiratory Sensory Cerebral
Cardiovascular Effects of +Gz:
BP above the heart BP below the heart blood pooling lower extremities CO and BV 10 sec delay in reflex Petechial hemorrhages
Cardiovascular system your BP forces blood up to your brain high Gs force the blood down away from your
head ‘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 turn1. press-to-test G-suit2. pull about _ Gs for at least 10 sec
no strain
3. OPTIONAL: gradually increase Gs without straining until you see some light lossdetermines 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?” the carotid bodies in your neck sense a
change in BP and initiate the cardiovascular reflex to maintain blood flow to your head
with increased Gs you see lower BP in your neck, and– your pulse increases– blood vessels throughout your body tighten up
this raises your BP and increases your relaxed G-tolerance
G-warm-up maneuver ...
gives you about 3/4 G additional relaxed G- tolerance protection
but it takes 10-15 seconds to occur– might notice more light loss on first pull of
the day and lasts only about 10-15 minutes
– so might consider doing G-warm-up close to the time that you’ll be needing the extra help
Push-Pull Effect with sustained negative Gs
push over, or level inverted flight
– BP rises in your head and your carotid bodies compensate by:
slowing your pulse, and dilating your blood vessels
– this lowers your BP in about 10-15 sec but normally + Gs come on just as your
BP is falling and you can GLOC at 3Gs! So avoid +Gs after sustained -Gs
– won’t occur unless -Gs last over 3-4 sec.
Petechia polka-dot bruises in dependent areas
where there is no counter-pressure caused by high, sustained Gs worse when you haven’t flown for
awhile like a bruise, looks worse the next
day, but fades out in 3 - 5 days are not contagious!
Respiratory Effects
AtelectasisHard to inhale
Atelectasis chest tightness and feel short of breath
after breathing 100% oxygen– release one side of oxygen mask
makes you cough 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
worse after sustained Gs the cough is the cure -- this re-inflates the
air cells and relieves the unpleasant feeling
Hard to inhale may feel like you can’t get enough air in due to physical forces compressing your
chest– breathing is usually rather easy -- this isn’t
you just have to work at it hypoxia may contribute to decrease in
performance, or increased likelihood of GLOC or ALOC
be efficient -- another reason not to work any harder than you have to!
Visual effects of +Gz:
in retinal circulation in retinal perfusion grayout or blackout visual field
Vision Loss1. tunnel vision ==> in-from-the-sides 2. “dimmer switch effect”3. splotches4. curtain5. combination/variations over time.
Vision loss may be asymmetric.
One sided light loss when check-6, normally
inadvertently tilt our head a little, so one eye becomes higher than other
top eye loses light before lower eye but we tend to “use the good eye”
and ignore the light loss the light loss in the top eye is the
GLOC warning!
G-Excess Illusion head tilt during a turn is misunderstood
by the body, which thinks your head has tilted more than it really has
but since you know where your head is, you think that the plane experienced an uncommanded pitch-up
watch out during a sustained turn don’t go by your instruments!
Cerebral effects of +Gz:
cerebral perfusion cerebrospinal fluid pressure
Buffer Period
your brain functions normally without any blood flow for about 6 seconds, then simply shuts down!– probably a self-protective mechanism
answer to today’s quiz question is:
6 sec
Stohl curve
GLOC Trap
get in habit of waiting for light loss before we start to strain
but may have no light loss warning before GLOC above 6 Gs
Neurological Effects Cognitive changes -- error making
– some fatigue related, some ALOC ALOC -- “Almost GLOC”
– impairment but not LOC– typical “almost lost it” scenario
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 GLOCG-induced loss of consciousness1. Absolute Incapacitation Period
– classic LOC -- out cold– varies 1-18 sec, mean 12 sec
typical in-flight GLOC is short: 1-6 sec as pilot lets go of the stick, plane goes to
1G
– flailing is common blood flow returns in watershed pattern
2. Relative Incapacitation Period– 1-24 sec additional– lights are on, but no one is home
subject is upright, looks OK, but 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 ... have some tingling or numbness have some twitching or jerking have a pleasant dream not realize that you GLOCed! be a little confused or disoriented be aware that you have lost your
hearing 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
the G level at which you have significant light loss without doing a straining maneuver.
relates to heart-to-eye distance– body shape– seat-back angle
varies– from person to person– from day to day
same for women and men 4 to 6 Gs for most people obviously different with or without
an anti-G suit does not relate to physical training
Relaxed G-Tolerance
your relaxed G tolerance is increased
by tilt-back seat
– lowers shortens heart-to-eye distance– less than 1G improvement seen in F-16
anti-G suit– onset delayed until after the Gs come
on recent G exposure --
the “training effect”
your relaxed G-tolerance is decreased
by: fatigue alcohol dehydration illness medication layoff from G exposure
Straining G-tolerance the highest G-level you can stand
when doing your best straining maneuver
but is hard to measure and study does relate to physical strength, and
is improved by working out physical training improves your
ability to repeatedly strain without wearing out
Endurance G-tolerance the time you can keep straining
against varying G levels until you are exhausted
hard to measure, hence hard to use reliably in research
improved by both aerobic and anaerobic training!
Aerobic Training was once thought to decrease your
relaxed G-tolerance; probably not true
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 ...
does not affect your relaxed G-tolerance
does improve your strength and endurance G-tolerance– pays off on long, difficult
engagements, and on frequent flights
Physical Training
So, train the muscles you strain– your goal is sustained, repeated
straining with rapid recovery include aerobic training my personal view is that you are
better served by understanding Gs, and doing what you have to effectively and efficiently
Neck Strengthneck pain is #1 cause of down time for
high-G aviatorsmovement under Gshelmet, mask, NVGs, etc.
Great Benefits come with neck strength better control (don’t want to kiss your belly button!)
less likely to be injured
so, include neck strength training in your weight workout!
Neck Pain/Injury leading cause of down time for high-G
aviators associated with high rate of G onset
(“snatching on the Gs”) non-pilot can’t anticipate G onset
head movement under Gs additional head mounted equipment good neck strength training minimizes
injury potential
The “Det Effect”or, “Where’d my G-tolerance
go?” Training Effect
– G-tolerance increases when you fly Gs Layoff Effect
– and drops off again when you don’t
Training Effect relaxed G-tolerance will increase all by
itself with frequent exposure to Gs– it’s not flight time, but “G-time”
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 don’t ever have to strain.
You get used to not having to strain
Engineering changes to improve G tolerance
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
anti-G suit– always lags the G onset
start your muscle strain before the Gs come on -- esp before high Gs
– gives a 1G increase in relaxed G-tolerance
positive pressure breathing with chest jerkin and Eagle anti-G suit
can sustain 8 Gs without straining! can keep talking and breathing
throughout high Gs so increases your endurance too
– less straining– better breathing
high Gs still suck, though....
Navy Combat Edge
Proper G suit fit ... G-suit helps you by doing some of the work strain first, then slack off after the G-suit fills fit should be snug, not tight
too loose just takes longer to fill up
– while standing, should easily slip: two fingers down by the thigh and calf, and open hand down the front
release G-suit when you need to (spring, fall)
AGSM M-1 classic grunt L-1 glottis closed completely “Hook” maneuver I say it’s 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 maneuver1. 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 airit’s hard to inhale under high Gs
5. work only as hard as you have to