HUMAN
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FACTORS - CHUF
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BODY WEIGHT
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● Body weight can be measured via BMI or the pinch test
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BODY MASS INDEX
● Attempts to provide indication of appropriate weight range per
height
● Weight (kg) / height (m)^2
● BMI <18 is underweight
● BMI 18<25 is normal weight
● BMI >25 is overweight
● BMI >30 is obese
WEIGHT LOSS
● Given body weight is food intake relative to energy expenditure,
weight loss can be achieved by:
○ Reduce food intake
○ Increase energy expenditure through exercise
● Rules from the National Heart Foundation:
. Reduce fat intake
. Reduce salt intake
. Reduce sugar intake
. Eat more fruit, cereal, vegetables and wholemeal bread
. Eat a balanced diet through a variety of foods
. Eat proper meals at regular intervals, refraining from meal-
skipping
. Exercise regularly, at least 3 times a week with 30 minute
duration, where resting heart rate is doubled
,THE7 PINCH TEST
● Pinched skin fold just above the hip should be no more than 12 mm
thick
● If greater than 20 mm, fitness level should be improved
DIET
● In addition to its effect on body weight, diet can also contribute to
illness and disease
● Poor diet can aggravate gout
● Poor diet can increase the risk of heart problems, including high
blood pressure
● Poor diet may also lead to gastro-intestinal upsets
GOUT
● Imbalance of uric acid in the body leading to arthritic-type pain
● Aggravated by poor diet and high alcohol intake
GASTRO-INTESTINAL UPSETS
● Bacterial contamination of food or drink
● Most common cause of pilot incapacitation during flight
● Risk can be reduced by:
○ Avoiding foods kept hot for long periods of time
○ Avoiding seafood, especially oysters and shellfish
○ Avoiding foods with cream or milk
○ Eating fresh fruit and vegetables, salads, bread, or freshly
cooked hot meals
○ Eating canned food
OPERATING IN NON-OPTIMAL ENVIRONMENTS
● Body is most comfortable operating when temperature is between 21
and 27 degrees, with between 40% and 60% relative humidity
, ● Hot environment is defined as 32 degrees and beyond, and can
cause heat stress
○ Effects are tiredness, lack of concentration, heat exhaustion
○ Overcome by drinking water, wearing light fitting clothes,
protecting skin from sun
● Heat stress can also occur when spending too much time in the sun
○ Could be sunbathing, time in sun without adequate protection or
insufficient water intake
○ Effects are lower concentration leading to poorer decision-
making, however may be difficult to notice given lack of
negative physical effects or environment might be comfortable
○ Overcome by drinking water, wearing light fitting clothes,
protecting skin from sun
● Cold environment is defined as 10 degrees or lower, and can cause
heat stress
○ Body may lose more heat than it can produce
○ Effects are shivering, drowsiness, poor concentration or
hypothermia
○ Overcome by being warmly clothed
SURVIVAL KIT
● Kept on board when flying in extreme temperatures
● In summer, this is at least plastic bottles of water
● In winter, this is at least warm clothes, matches and high-energy
food
HEAT EXHAUSTION
● When the circulatory system cannot meet the increased flow
requirements caused by high body heat
● When the body becomes too hot, the blood vessels dilate and shift
closer to the skin surface in order to cool down
HYPOTHERMIA
, HYPOTHERMIA
● When the body can no longer maintain its core temperature
● Caused by long immersion in cold water or exposure to cold
environments without protection
● Symptoms include:
○ Impairment of thinking
○ Apathy
○ Unconsciousness
○ Death
DEHYDRATION
● Occurs when the body is lacking sufficient water
● Common in flight where air at altitude is drier than at sea-level,
causing the body to perspire more and lose water
● Often unnoticeable as there is no “sweaty” feeling
● Effects are drying of the nasal passages, prickly sensation in the
eyes, emotional disturbance, irrational decision-making and
malfunction of bodily processes
● Overcome by drinking more water or adjusting air conditioning to
provide more relative humidity
BLOOD DONATIONS
● CASA recommends waiting 24 hours before flying after a blood
donation
● Lesser blood volume may cause tiredness or lowering of blood
pressure
SMOKING
● Increases risk of cancer of lungs, tongue, larynx, oesophagus and
pancreas
● Increases risk of heart attack by 100%
○ 200% if coupled with high blood pressure or cholesterol
○ 1,000% if on the contraceptive pill