aviation physiology · aviation physiology visual illusions there are many different type of visual...

Aviation Physiology

www.AviatorsNavigators.comRev.11/2019

www.AviatorsNavigators.com

Aviation Physiology

Vision in Flight

Our vision sensors are our eyes.• They operate differently during day and night times

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Aviation Physiology

The Eye

The vision is possible due to light striking a photosensitive layer called the retina. This consists of light sensitive receptors known as cones and rods.

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Aviation Physiology

Cones – Day Receptors

• Are concentrated around the center of the retina (Fovea area)• These allow to perceive color by sensing red, blue and green light• They do not function well in darkness• Direct viewing should be use during daytime

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Aviation Physiology

Rods – Night Receptors

• Are concentrated outside of the Fovea area• These allow to perceive black and white (Peripheral Vision)• Objects that move are perceive it better by rods• They do function well in darkness• Offset viewing the eyes during night time

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Aviation Physiology

Night Vision

• Bright lights should be avoided for at least 30 minutes before a night flight• Red cockpit or flightdeck lighting enhances dark adaptation while white

lighting impair vision• Keep the instrument panel and interior lights turned up no higher than

necessary• Your diet and physical health will determine how well you can see at dark

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Aviation Physiology

Other Factors That Can Affect Night Vision

• Carbon Monoxide• Smoking• Alcohol• Certain drugs• Lack of oxygen

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Aviation Physiology

Night Scanning

• When scanning for traffic move eyes slowly and in small sectors• Use off-center viewing and avoid staring in one place for too long

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Aviation Physiology

Aircraft Lighting

• Position lights – enable to see where an aircraft is, as well as its direction of flight.

• Also, a flashing red or white anticollision lights are required during night time.

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Aviation Physiology

Visual Illusions

There are many different type of visual illusions:

• Autokinesis – Occurs by staring to a single point of light against a dark background.

• Night Myopia – Is the eyes tendency to focus between three and six feetin front of you due to the lack of reference point.

• Landing – It occurs in many forms and associated with featureless terrain.• Tendency to fly lower than normal approach

(Rain, haze, or dark runway)• Tendency to fly higher than normal approach

(Cause by bright light runway)

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Aviation Physiology

Landing Illusions

Situation

Upsloping Rwy or Terrain

Narrower Than Usual Rwy

Featureless Terrain

Rain on Windshield

Haze

Downsloping Runway or Terrain

Wider Than Usual Runway

Bright Runway and Approach Lights

Penetration of Fog

Illusion

Greater Height

Greater Height

Greater Height

Greater Height

Greater Height

Less Height

Less Height

Less Distance

Pitching Up

Result

Lower Approaches

Lower Approaches

Lower Approaches

Lower Approaches

Lower Approaches

Higher Approaches

Higher Approaches

Higher Approaches

Steeper Approaches

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Aviation Physiology

Landing Illusions

• For advance warning of conditions that could cause visual illusions, consult the aeronautical chart and airport facility directory

• Always use visual approach slope indicator system to verify your landing approach to any runway

PAPI System VASI System

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Aviation Physiology

Spatial Disorientation

When your body is in state of conflict with what you see and feel.

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Aviation Physiology

Spatial Disorientation

The human body has been designed to lived and operate in a two dimensional environment when feet are on the ground. However, fly takes place in tri-dimensional environment.

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Aviation Physiology

Visual Sense

Helps to keep your balance and position relative an object around you.

Vestibular Sense

Semicircular canals in the inner ear helps identify direction of turn, climb, descent, or speeding up or slowing Down.

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Aviation Physiology

Vestibular Sense

Inner ear consists of fluid and hair cells

Hair Cells

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Aviation Physiology

Vestibular Sense

The brain receives stimulation from the inner ear and eyes and it provides motion and balance around the axis.

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Aviation Physiology

Kinesthetic Sense

• Obtaining information from your body nerves in your skin• It is unreliable because brain cannot tell different between input

cause by gravity or maneuvering G-loads

“FLYING BY THE SEAT OF PANTS”

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Aviation Physiology

Disorientation

• It takes place when the brain receives conflicting messages from your sensory organs

False Information

Skin Nerves

Rely on Instrument

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Aviation Physiology

Spatial Illusions

All the optical illusions is the result of visibility restriction by weather or darkness.

• Graveyard Spiral – A prolonged constant rate of turn. Fluid in the inner ear stops moving

• Coriolis Illusion – A prolonged constant rate of turn. Induce by tilting head down or constant head movements. This cause inner ear fluids motion simultaneously.

• Leans – When an abrupt correction is made to a bank. Inner ear semicircular canal sense a motion in the opposite direction

• Somatogravic Illusion – A rapid acceleration or deceleration. Creates an illusion that you are on a climb or descent even though you are still in a straight and level flight.

• Inversion Illusion – Abrupt changes from a climb to straight and level flight. Creates the illusion that you are tumbling backward

• False Horizons – Occurs when the natural horizon is obscured or not visible.• Flicker Vertigo – a light source flickering can results with nausea, convulsion and

unconsciousness• Motion Sickness – Occurs by looking to a single object in the airplane

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Aviation Physiology

Respiration

• Oxygen is attached to the hemoglobin in the bloodstream• Oxygen releases energy and this process creates a waste product

called carbon dioxide (CO2)• Co2 in your bloodstream is released back to the atmosphere• As altitude increases the density of air decreases• The altitude at which body becomes starved for oxygen depends

upon your level of activity

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Aviation Physiology

Hypoxia

Lack of oxygen in the bloodstream

Types:

• Hypoxic – Occurs when there is not enough oxygen in the atmosphere

• Anemic – Occurs when the blood is not capable to carry enough oxygen to the cell in the body

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Aviation Physiology

Hypoxia Symptoms

• Impaired judgement• Lightheaded• Dizziness• Sweating• Blue fingernails• A slowing of decision making• Feeling of euphoria• Changing in personality traits• An increase in breathing rate• Tingling or warm sensation

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Aviation Physiology

Useful Consciousness

The maximum time you have to make a rational life saving decision and carry it out following a lack of oxygen at a given altitude.

Altitude While Seating Quietly

During Moderate Activity

40,000 Feet 30 Seconds 18 Seconds

35,000 Feet 45 Seconds 30 Seconds

30,000 Feet 1 Minute and 15 Sec 45 Seconds

25,000 Feet 3 Minutes 2 Minutes

22, 000 Feet 10 Minutes 5 Minutes

20,000 Feet 12 Minutes 5 Minutes

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Aviation Physiology

Carbon Monoxide

The most common cases of anemic hypoxia come from carbon monoxide poisoning.

• It suspected turn aircraft heater off (faulty heater system)

Symptoms:

• Headache• Dizziness• Loss of muscle power

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Aviation Physiology

Blood Donation

• Another type of anemic hypoxia can be caused by the loss of blood.

• Your blood can take several week to come back to normal, so there is risk flying during this time

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Aviation Physiology

Supplemental Oxygen

To avoid the effect of hypoxia do not fly for prolonged period of time above 10,000 feet MSL during day or 5,000 feet MSL at night without breathing supplemental oxygen.

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Aviation Physiology

Hyperventilation

Rapid or extra deep breathing can cause this condition as result of emotional tension, anxiety or fear.

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Aviation Physiology

Hyperventilation Symptoms

• Dizziness• Tingling of the fingers and toes• Muscle spasms• Coolness• Drowsiness• Weakness or numbness• Rapid heart rate• Apprehension and mental confusion• Loss of consciousness

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Aviation Physiology

Pressure Effects

As you climb or descend, changes in atmospheric pressure affect many parts of your body. Half of the atmospheric pressure lies below 18,000 feet.

28,000 feet - 4.8 p.s.i Volume Tripled

18,000 feet - 7.3 p.s.i Volume Doubled

Sea level - 14.7 p.s.i Original Size

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Aviation Physiology

Ears

The eustachian tube keeps the pressure equalized between the ear canal and the middle ear. When the pressure is equal, the ear drum is not distended.

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Aviation Physiology

During Ascend

When the eustachian tube does not open during an ascent, the positive air pressure in the middle ear pushes the ear drum outward toward the ear canal. Then you experience a slight hearing loss because eardrum cannot vibrate as freely as before.

Blockage

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Aviation Physiology

During Descent

During a descent, the pressure inside the ear canal increases, while lower pressure air remains in the middle ear. This forces the eustachian tube to close and causes the eardrum to be pushed inward.

Close

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Aviation Physiology

Pressure Imbalance

• Most people are aware of the pressure imbalance during descent• You can open the eustachian tube by yawning, swallowing or

chewing

Close

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Aviation Physiology

Trapped Air Discomfort

• Sinuses – air trapped in the sinus cavities• Teeth – air trapped in a cavity• Gastrointestinal Tract – gas inside this system expands and cause pain• Scuba Diving – Nitrogen absorbed comes out and formed bubbles in

the tissues and bloodstream

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Aviation Physiology

Alcohol, Drugs and Performance

The hazardous effects of alcohol and drugs can sometimes cause serious problems in the flying environment. They can produce side effects.

• Depressants – Slow motor responses and mental process• Alcohol – Increase heart rate, blood pressure and depress the nervous

system. Also, body can’t metabolized alcohol at higher altitude

Example:• 1 Oz at Sea Level = 3 Hours• 1 Oz at 12,000 Feet = 12 Hours

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Aviation Physiology

Alcohol, Drugs and Performance

The hazardous effects of alcohol and drugs can sometimes cause serious problems in the flying environment. They can produce side effects.

• Caffeine - Nervousness• Nicotine - Fatigue• Smoking - Hypoxia• Prescription Drugs or Over The Counter - Ensure with doctor that you

can use them while flying activities are considered

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aviation physiology · aviation physiology visual illusions there are many different type of visual...

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