Physiology & Aeronautical
Decision Making
Sensory Systems for Orientation
• Visual System
• Vestibular System
• Postural
• Auditory Cues
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Visual System
• Primary method of orientation
• Responsible for 80% of flight information received
• Works similar to a camera focusing light through a lens
• Sends signals to the brain via an optic nerve
• Subject to visual illusions and contains blind spots
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Visual System
• Light enters the eye through the cornea
• It then passes through the lens and falls on the retina
• Sensors located on the retina convert light into electrical impulses
that are sent to the brain via the optic nerve
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Visual System
• Rods
• Sensors concentrated on the peripheral of the retina
• Highly sensitive to light
• Primarily used during low light conditions, at night
• Do not detect color
• Contains rhodopsin, visual purple
• Optic Nerve
• Contains no rods or cones
• Result in loss of vision
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Visual System
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Visual System – Blind Spots
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Black and White Vision
• Images cast on the retina are converted from light energy into
electrical impulses then sent to the brain
• Rods contain the protein rhodopsin which in turn contains a
derivative of Vitamin A
• Located on the periphery of the eye, the rods are 10,000 times more
sensitive to light than the fovea
• A healthy human has about 120 million rods in each eye
• Rods are light sensitive and used for viewing in low light conditions,
such as night time
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Color Vision
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Color sensitive cells in the retina are called cones
There are 3 types of cones: Red, green, blue
6 million cones add color detail to images sensed by the rods
The photo pigment in the cones responsible for color are called rhodopsin
Each type of cone transmits light into wavelengths of light energy sent to
the brain
• Cones require much higher light energy than rods to elicit a response
• They are used for detailed viewing during day light hours
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Limits to the Visual System
• Adjusting from high light to low light conditions
• Vitamin A deficiency and its affect on vision
• Optical illusions
• Daylight viewing vs. night time viewing
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Socrative Multiple Choice 1
• Which Mineral is Important for the Eyes to Function?
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Vitamin A
Omega 3
Vitamin C
Grape Soda
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Vestibular System
• The inner ear houses 3 semi-circular canals
• Fluid in the canals orientate the body along the three main axes
• These axes correspond to the axes of pitch, roll and yaw in an aircraft
• This system falls secondary to the ever-dominant visual system
• False signals can overwhelm an untrained pilot
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Location of Vestibular System
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Semicircular Canals and Corresponding Axes
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Inside the Semicircular Canal
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Fluid in Motion Starting a Turn
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Loss of Sensations
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Postural and Auditory
• Postural uses the body’s center of gravity
• A person can be upside down, but if pulling 1 positive G load, it will feel like
sitting normally right side up
• Auditory uses aural queues when other senses are limited
• Engine sound (low pitch = airspeed reduction)
• Wind speed (increase in wind noise = airspeed gain)
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Postural Orientation
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Illusions in Flight
• Vestibular Illusions
• When visual cues are not received and the body has to rely on information
being sent from the vestibular nerve
• Visual Illusions
• Due to optical illusions created by the eyes. Experienced pilots are aware of
these illusions and are not as susceptible
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Spatial Disorientation
• When a pilot becomes unaware of his or her position due to a
disharmony between multiple senses
• When this occurs, full focus should be placed on the flight
instruments in order to maintain safe flight attitudes
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Postural and Auditory
• Rapid acceleration can feel like
pitching up
• This is dangerous during low
visibility takeoffs and go around
due to proximity to the ground
• While accelerating, the pilot
might falsely sense an over
pitching moment and
incorrectly pitch down
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The Leans
• Discussed before, during long durations of constant motion, the fluid
can re-settle in the canal
• This can lead to a sense of not turning during a turn
• When the pilot rolls wings level, the fluid will begin flowing in the
opposite direction, giving the false sensation of beginning another
turn
• This is dangerous because he will try to correct by attempting to roll
until he feels like he is wings level, when in fact he will be in a turn
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Coriolis Illusion
• Occurs when the fluid in a canal of the same axis of motion, begins to
flow at the same rate as the motion
• Due to rapid head movement fluid in another canal will begin to
move giving the false sense of motion in the new canal’s axis
• Pilot must develop an instrument scan which minimizes head
movement
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Inversion Illusion
• Due to abrupt level off from climb
• Body feels as if it were tumbling backwards
• Pilot might incorrectly adjust for level by pushing nose down into a
dangerous attitude
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Elevator Illusion
• Due to strong updraft or downdraft
• Pilot feels as if in a climb or descent
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Graveyard Spirals
• Prolonged turns lead to sense of not turning
• Aircraft begins to descend in turn and pilot pulls back on yoke
• Because he is pulling back but not reducing bank, the descending turn
steepens into a tight spiral
• Proper recovery is to roll level wings (using the Attitude indicator) and
slowly recover from the dive, reducing throttle to idle to avoid
exceeding VNE
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Graveyard Spin
• After recovery from a spin
• Pilot feels as if spinning in opposite Direction and will incorrectly try to recover
from a non-existent spin, thus causing another and crashing
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Coping with Spatial Disorientation
• Do not make abrupt movements
• Always be aware of the state of the aircraft
• Understand the cause of the illusion
• Correct based off of the aircraft instruments
• Cross-check instruments for accuracy
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Visual Illusions - Autokinesis
• In a dark sky with few references
• A single light, or point of light to focus on
• Eye cannot fully focus and will begin rapid movement
• The object will appear to move
• Pilot might try to maintain attitude position and chase the light
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Visual Illusions – False Horizon
• Stars, boats, or sloping clouds
create a new horizon
• Pilot tries to align aircraft with
new horizon
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Empty-Field Myopia
• Occurs at night
• When the eyes have nothing to focus on, the eye will default to focus
4 feet in front of you
• This inhibits that ability to see objects far away unless the pilot
forcibly tries to focus on other distances
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ICEFLAGGS
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Inversion
Coriolis Illusion
Elevator Illusion
False Horizon
Leans
Autokinesis
Graveyard Spiral
Graveyard Spin
Somatogravic Illusion
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Socrative Short Answer 1
• If I focus on a light during the middle of the night, it appears to me
that it starts moving. What illusion am I experiencing?
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Other Illusions…
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Runway Width
• A narrow runway makes pilot appear high and fly a lower than normal
approach, possibly striking terrain
• A wide runway makes the pilot appear low and fly a higher than
normal approach, possibly over shooting the runway
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Runway Slope
• An up-sloping runway makes pilot appear high and fly a lower than
normal approach, possibly striking terrain
• A down-sloping runway makes the pilot appear low and fly a higher
than normal approach, possibly over shooting the runway
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Featureless Terrain / Black Hole Approach
• Lack of terrain makes pilot appear high
• Pilot flies lower approach
• Approaching a runway at night with little or no other light references
make it difficult to judge distance, altitude and proper glide path
• Use your PAPI or VASI whenever able!
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Haze and Fog Effects
• Haze
• Haze makes object appear further away
• Pilot feels higher on an approach and flies lower
• Fog
• Flying into fog creates a pitching up illusion
• Pilot starts to fly lower
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Coping With Visual Illusions
• Understand illusions
• Anticipate illusions
• Fly higher if possible when landing
• Rely on the instruments
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Socrative Short Answer 2
• If I approach to land on an upsloping runway, I will appear to be
___________ on approach, therefore I should attempt to fly slightly
__________ than what appears.
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Physiological and Psychological Factors
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Affects of Stress
• Stress is a good thing (Eustress) in the right amount
• Too much stress can suddenly cause human performance to
deteriorate (distress)
• Physical, psychological, and physiological stressors
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Affects of Fatigue
• Acute fatigue vs. chronic fatigue
• Inability to focus
• Reduction in mental and physical ability
• Increases frequency of mistakes
• Impairs judgment
• Can have deadly consequences
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Affects of Alcohol
• Histotoxic hypoxia
• Impairs judgment
• Decreased reaction time
• Increases fatigue
• Increased effects at higher altitude
• Regulations regarding alcohol…
• Crew member requirements
• Passengers requirements
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Drugs
• Illegal drugs (narcotics, opiates etc.)
• Prescription medications
• Over-the-counter (OTC) medications
• Most drugs not tested at high altitudes
• Always consult an Aviation Medical Examiner (AME)
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Decompression Sickness
Cause:
• Exposure to low barometric
pressures cause nitrogen (normally
dissolved) to form bubbles in
various parts of the body
• Bends (joints)
• Chokes (lungs)
• Skin Bends (skin)
• Neurologic (brain/spinal cord)
DCS After Scuba Diving:
• Allow body sufficient time to
rid itself of excess nitrogen
Recommended waiting
time:
• 12 hours after
• < 8,000’ (no decompression
stop)
• 24 hours after
• > 8,000’ (no decompression
stop)
• Any dive requiring
decompression stop
IMSAFE Self-Checklist
• I – Illness
• Do not fly due to sinus and ear blockages
• M – Medication
• Even non drowsy medication has side effects at high altitudes
• S – Stress
• Acute Stress: Due to immediate threat
• Chronic Stress: Levels that create intolerable burden
• Some stress is good, too much is detrimental
• A – Alcohol
• Regulations vs. personal minimums
• F – Fatigue
• Acute: Short periods of time
• Chronic: Long periods of fatigue
• E – Eating
• Maintain a healthy diet and stay hydrated
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Hypoxia
• Hypoxic
• Insufficient oxygen available to the body as a whole
• Hypemic
• Blood is unable to transport a sufficient amount of oxygen to cells
• Histotoxic
• Inability of cells to effectively use the oxygen
• Stagnant
• Oxygen-rich blood in the lungs is not moving to the tissues that need it
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Socrative Short Answer 3
• What type of Hypoxia will I experience if I sit still for a long period of
time?
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Oxygen Requirements – 91.211
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Socrative Short Answer 4
• At what altitude is everyone required to have oxygen on the aircraft?
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Cockpit Resource Management
• Organized cockpit
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Have all publications readily available and organized neatly
Fold all charts neatly to the page that shows route of flight
Dial in all frequencies and navigation frequencies before workload increases
If using GPS, have route programmed before departure
Be familiar with where everything is located in the cockpit
Be familiar with the entire route and airport approaches
Take more than one pen or pencil
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Crew Resource Management
• Use inside and outside resources for help
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Passengers and Crew Members
Air Traffic Control
Flight Service Station
Dispatchers
Other Aircraft
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Hazardous Attitudes
• Macho: “I can do it.”
• Invulnerability: “It won’t happen to me.”
• Impulsivity: “Do it quickly.”
• Anti-Authority: “Don’t tell me.”
• Resignation: “What’s the use?”
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Pave Checklist
• Pilot
• Aircraft
• enVironment
• External Pressures
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5 P’s
• The Plan
• The Plane
• The Pilot
• The Passengers
• The Programming
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Decide Model
• Detect a problem
• Estimate the need to react
• Choose a course of action
• Identify possible solutions
• Do the necessary actions
• Evaluate the effect of the action
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Risk Management
• Flight Risk Assessment Tools
• The Swiss Cheese Model of Accident Theory
• When in doubt – DON’T GO OUT
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References
• Jeppesen Private Pilot Flight
• Pilot’s Handbook of Aeronautical Knowledge
• Airplane Flying Handbook
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