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catching up, but they tried anyway.
The first one wrote itself off in a
ditch because it was going too fast,
the driver of the second suddenly
put the brakes on because he
realised there had been an ejection
and that he might run over a pilot
on the runway, at which point the
number three appliance smashed
into the back of him.
We are in a similar situation – how
many times have you jumped into
the cockpit of a different machine,
to find the switches you need in a
totally different place? This doesn't
help you if you rely on previous
experience to find what you need (in
emergencies you tend to fall back to
previous training), so the trick here is
to know what you need at all times,
and take the time to find out where
it is (and read the switches).
Physiological (The Body)
The human body is wonderful, but
only up to a point. It has limitations
that affect your ability to fly
efficiently, as your senses don't
always tell you the truth, which is
why you need extensive training to
fly on instruments, as you have to
unlearn so much. The classic
example is the "leans", where you
think you're performing a particular
manoeuvre, but your instruments tell
you otherwise.
238 JAR Private Pilot Studies
Why do you need to learn about the
body? Well, parts of it are used to
get the information you need to
make decisions with. And, of course,
if it isn’t working properly, you can’t
process the information or
implement any action based on it.
G Tolerance
The body can only cope with certain
amounts of G-force, from the effects
of acceleration. When there is none,
you are subject to 1G.
Negative G acts upwards and can
increase the blood flow to the head,
leading to red out, facial pain and
slowing down of the heart. In
addition, your lower eyelids close at
–3G. Positive G is more normal, but
will drain the blood, with the
obvious consequences, including
loss of vision, called grey out, at
+3.5G This could end up as black out
and unconsciousness at +6G. Both
are affected by hyperventilation,
hypoxia, heat, hypoglycaemia,
smoking and alcohol, all of which
are discussed more fully below.
The valsalva manoeuvre can be used to
help cope with high G (close your
throat and hold your nose), or you
could use a pressure suit.
Impact-wise, the body can tolerate
25G vertically and 45G horizontally
- if you don't wear shoulder straps,
tolerance to forward deceleration
reduces to below 25G, and you will
jackknife over your lapstrap with
your head hitting whatever is in
front of it at 12 times the speed it is
coming the other way.
Body Mass Index (BMI)
This is calculated by your weight in
kg divided by your height squared, in
metres squared.
If it is over 30, you are obese. This
could lead to diabetes and heart
disease, and reduce your ability to
cope with hypoxia, decompression
sickness and G tolerance.
The Central Nervous System
This consists of the brain and spinal
cord, though, for exam purposes, it
also includes the visual and aural
systems (eyes and ears),
proprioceptive system and
chemosensory system (smell).
The autonomic nervous system
regulates vital functions over which
you have no conscious control, like
heartbeat and breathing (unless
you're a high-grade Tibetan monk,
of course).
Although the brain is only 2% of the
body mass, it takes up to 20% of the
volume of each heartbeat – its blood
supply needs to be continuous, as
the brain cannot store oxygen.
Eyes
Vision is your primary (and most
dependable) source of information.
It gets harder with age to distinguish
moving objects; between the ages of
40 and 65, this ability diminishes by
up to 50%. This is only one of the
limitations of sight, and we need to
examine the eye to see how you
overcome them.
The eye is nearly round, and its
rotation in its socket is controlled by
external muscles:
Human Factors 239
It has three coatings; the sclerotic,
which is transparent at the front; the
choroid, which lines the sclerotic and
contains tiny blood vessels, and the
retina, which is the light sensitive bit
that detects electromagnetic waves
of the frequency of light, and
converts them to electrical signals
that are interpreted by the brain, and
which is sensitive to hypoxia.
This means you see with the brain as
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