Spatial Disorientation

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Spatial
Disorientation
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OUTLINE

• Review of Spatial Disorientation Terms
• Discuss the Role of Vision in Maintaining
  Equilibrium
• Components of the Vestibular System
• Types of Vestibular Illusions
• Mechanisms of Proprioceptive Equilibrium
• Identify the Classifications of Vestibular
  Illusions
• Prevention and Treatment of Spatial
  Disorietation

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REFERENCES

• FM 1-301, Aeromedical Training for Flight
  Personnel

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TERMINOLOGY

• Vertigo
• Sensory Illusion
• Spatial Disorientation

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SENSES OF BALANCE

• Visual System
• Vestibular System
• Proprioceptive System

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FOCAL VISION

• Also called Central Vision
• Done consciously
• Enables one to determine distance
• Allows for depth perception
• Presents us with clear view

USASAM SD NEWS
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AMBIENT VISION

• Also called Peripheral Vision
• Done unconsciously
• Detects motion and attitude cues
• Helps to provide balance

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VISUAL SYSTEM

• Vision is the most reliable sense used during
  flight
• 80 of orientation while flying is dependent on
  the visual senses

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THE CONDITION MOST SUSCEPTIBLE TO SPATIAL
DISORIENTATION IS --

• During a sudden and unexpected transition from
  VMC to IMC flight conditions

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VESTIBULAR SYSTEM

• Semicircular Canals
• Otolith Organs

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Semicircular Canals
Otolith Organs
Auditory Nerve
Cochlea
Ossicles
Ear Drum
Middle Ear
External Ear
Eustachian Tube
Opening to Throat
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FUNCTIONS OF THE VESTIBULAR SYSTEM

• Triggers reflexes that stabilize the eyes during
  movement of the head or body
• Assist automatic reflexes
• Provides orientation information in the absence
  of vision

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VISUAL TRACKING

• Maintains focus of the retinal image

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NYSTAGMUS
A rapid flickering motion of both eyes back and
forth, seriously degrading visual acuity to
20/200 for a few seconds.
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REFLEX INFORMATION
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ORIENTATION WITHOUT VISION
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SEMICIRCULAR CANALS

• Right angles to each other
• Contains endolymph fluid

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FUNCTIONS OF THE SEMICIRCULAR CANALS

• Indicates Roll, Pitch, and Yaw
• Change in both speed and direction
• Responsive to angular acceleration and
  deceleration

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FUNCTION OF THE OTOLITH ORGANS

• The Otolith organs are stimulated by gravity and
  linear accelerations
• Change in speed without a change in direction
• Sensitive to linear acceleration and
  deceleration (forward and backward/up and down)

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FUNCTION OF THE OTOLITH ORGANS
FORWARD ACCELERATION CENTRIFUGAL
/CENTIPUAL
FALSE SENSATION OF BACKWARD FALSE SENSATION OF
UPRIGHT
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VESTIBULAR ILLUSIONS

• Somatogravic
• Oculoagravic
• Elevator
• Oculogravic

• Somatogyral
• The Leans
• Graveyard Spin
• Coriolis

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THE LEANS
Most common form of Spatial Disorientation
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Motion is usually undetected during a
subthreshold maneuver (less than 2o)
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Pilot corrects attitude and compensates for the
false sensation of turning in the opposite
direction
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• This illusion seldom affects both pilots
  at the same time

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Graveyard Spiral
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THE CORIOLIS ILLUSION

• The most deadly illusion
• Most likely to occur during an
• instrument approach

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CORIOLIS ILLUSION

• Pilot enters a turn stimulating one semicircular
  canal
• Pilot makes a head movement in a different
  geometrical plane
• Stimulating a 2nd / 3rd semicircular canal
• Results in overwhelming sensation of Yaw, Pitch,
  or Roll

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SOMATOGRAVIC ILLUSION

• Illusions created by the Otolith organs as a
  result of linear acceleration

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OCULOAGRAVIC

• Upward movement of the eyes during
• weightlessness, caused by rapid
• downward motion of the aircraft

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ELEVATOR ILLUSION

• Occurs during sudden upward acceleration
• Pilot perceives a nose up attitude
• Tendency to nose over aircraft

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UPRIGHT
UPRIGHT
AFT TILT
EXTREME AFT TILT
OCULOGRAVIC ILLUSION
NOSE HIGH SENSATION

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PROPRIOCEPTIVE SYSTEM
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SEAT OF PANTS FLYING

• Very unreliable means of orientation
• Dependent upon gravity
• Flying without reference to instruments

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CLASSIFICATION OF DISORIENTATION

• TYPE I - UNRECOGNIZED
• TYPE II - RECOGNIZED
• TYPE III - INCAPACITATING

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UNRECOGNIZEDType I

• Pilot does not consciously perceive any
  indication of Spatial Disorientation
• False inputs from sensory organs or cues
• Crashes with smile on their face

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RECOGNIZEDType II

• Pilot consciously perceives a problem, but may
  not know it is due to spatial disorientation
• Pilot can correct the situation

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INCAPACITATINGType III

• Pilot experiences overwhelming sensations
• Conflict of sensory inputs
• Unable to properly orient themselves by use of
  instruments or visual cues

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SPATIAL DISORIENTATION

• Prevention techniques

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SD PREVENTION

• Instruments-trust your instruments
• Good cockpit design
• Training
• Instrument proficiency
• Health
• Aircraft design
• Never try to fly both VMC and IMC at the same time

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PREVENTION (cont.)

• Never fly without visual reference points
• Trust the instruments
• Never stare at lights
• Dark adaptation
• Avoid self -imposed stresses (DEATH)

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TREATMENT

• Refer to instruments
• Develop and maintain cross-checks
• Delay intuitive reactions
• Transfer controls

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ENSURE THE INSTRUMENTS READ RIGHT !
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QUESTIONS ?
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