Aeromedical FactorsGroups B/D: First Year

Essential Questions

• What is a medical certificate and what ranks are there?

• What different types of physiological factors can affect pilots during flight?

• In what ways can your vision trick you during flight?

Obtaining a Medical Certificate

• Valid medical certificate required to exercise privileges of airman certificates (exception of glider and free balloon pilots)

• Acquisition of medical requires exam by AME (aviation medical examiner)

Obtaining a Medical Certificate

• Third class– Required for private or recreational– 3 years for under 40 years old, 2 years otherwise

• Second class– Required for commercial– 1 year

• First class– Required for ATP– 6 months

Obtaining a Medical Certificate

• Higher the class, more rigorous the standards• Higher class medicals have met requirements

for lower classes• First class lasts for 2 (or 3) years for

private/recreational, same applies for second class

• 14 CFR part 67• 14 CFR part 61

Physiological Factors Affecting Pilot Performance

• Hypoxia• Hyperventilation• Middle Ear/Sinus Problems• Spatial Disorientation• Illusions• Posture• Motion Sickness• CO Poisoning• Stress• Fatigue• Dehydration/Heatstroke• Alcohol• Drugs

Hypoxia

• Means “reduced oxygen” or “not enough oxygen”

• Most concern is with getting enough oxygen to brain

• Reduction in mental function while flying can result in life-threatening errors

• Hypoxia can be caused by insufficient supply of oxygen, inadequate transportation of oxygen, or inability of the body tissues to use oxygen

Symptoms of Hypoxia

• Cyanosis (blue fingernails/lips)• Headache• Decreased reaction time• Impaired judgment• Euphoria• Visual impairment• Drowsiness• Lightheaded or dizzy sensation• Tingling in fingers and toes• Numbness

• Time of useful consciousness describes maximum time the pilot has to make rational, life-saving decisions and carry them out at a given altitude without supplemental oxygen

Hyperventilation

• Excessive rate and depth of respiration leading to abnormal loss of carbon dioxide from the blood

• Disturbing symptoms can alarm the uninformed pilot

• Can lead to unconsciousness due to respiratory system’s overriding mechanism to regain control of breathing

• Breathing more rapidly than normal in a stressful situation can lead to hyperventilation

Symptoms of Hyperventilation

• Visual impairment• Unconsciousness• Lightheaded or dizzy sensation• Tingling sensations• Hot and cold sensations• Muscle spasms

• Breathe normally or into a bag to recover from hyperventilation. Talking aloud also helps.

Middle Ear and Sinus Problems

• Air inside body cavities expands due to difference in air pressure at higher altitudes

• Middle ear is a small cavity located in the bone of the skull

• Air can get trapped inside middle ear and cause a uncomfortable difference in pressure internally and externally

• Greater external pressure, eardrum will bulge inward; greater internal pressure, eardrum will bulge outward

Middle Ear and Sinus Problems

• This is why you don’t go flying when you’re sick!!!• Swelling can cause closing of Eustachian tube and

pressure difference cannot be relieved• Can be damaging to eardrums• Air pressure in sinuses also equalizes with

pressure in flight deck that connect sinuses to nasal passages

• Respiratory infection, allergies, colds, etc. can lead to slow equalization and cause discomfort

Spatial Disorientation• Lack of orientation with regard to position, attitude,

or movement of airplane in space• Three body systems working together to decide

orientation in space:– 1. vestibular system: organs in inner ear that sense position

by balance– 2. somatosensory system: nerves in skin, muscles, and

joints which, along with hearing, sense position based on gravity, feeling, sound

– 3. visual system: eyes sense position based on what is seen• Flying can sometimes cause systems to supply

conflicting information to the brain, leading to disorientation

Carbon Monoxide (CO) Poisoning

• CO is a colorless, odorless gas produced by all internal combustion engines

• CO prevents hemoglobin from carrying oxygen to cells, resulting in hypoxia

• Body requires up to 48 hours to dispose of CO• If CO poisoning is severe enough, it can lead to

death

Carbon Monoxide (CO) Poisoning

• Effects:– Headache– Blurred vision– Dizziness– Drowsiness– Loss of muscle power

Stress• Body’s response to physical and psychological

demands placed upon it• Stressor is an element that causes stress

– Physical stress (noise or vibration)– Physiological stress (fatigue)– Psychological stress (difficult work or personal situations)

• Acute stress– Immediate threat that is perceived as danger– “Fight or Flight”– Can lead to chronic stress

• Chronic stress– Level of stress that presents an intolerable burden,

exceeds the ability of an individual to cope, and causes individual performance to fall sharply

Fatigue

• FREQUENTLY ASSOCIATED WITH PILOT ERROR• Acute– Short term– Normal occurrence in everyday living

• Chronic– Long term– Usually has psychological roots

• Best way to prevent is to get adequate rest

Vision in Flight

• Of all senses, vision is most important for flight• Structure of eye includes an aperture, lens, mechanism for

focusing, and surface for registering images• Rods and cones are light-sensitive cells that convert light

energy into electrical signals that are sent to the brain• Cones

– Responsible for all color vision– Concentrated toward center of field of vision

• Rods– Responsible for detecting movement and provide vision in dim

light• No rods or cones in area where optic nerve enters eyeball

leaves blind spot in field of vision

Find Your Blind Spot

Autokinesis

• Caused by staring at a single point of light against dark background for more than a few seconds

• Light appears to move on its own after a few moments

• Focus eyes on objects at varying distances to prevent illusion and avoid fixating on one target

False Horizon

• Natural horizon is obscured or not readily apparent

• Can be generated by confusing bright stars and city lights

• Can also occur while flying toward shore of ocean or large lake

Night Illusions

• Pilots are more likely to fly a lower-than-normal approach

• Lights should always be as dim as possible during landing so as to have correct depth perception

• Visual obscurities can cause night illusions– Rain– Haze