Spatial Disorientation
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Transcript Spatial Disorientation
Spatial
Disorientation
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
REFERENCES
FM 1-301, Aeromedical Training for Flight Personnel
TERMINOLOGY
Vertigo
Sensory
Illusion
Spatial Disorientation
SENSES OF BALANCE
Visual
System
Vestibular System
Proprioceptive System
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
AMBIENT VISION
Also
called Peripheral Vision
Done unconsciously
Detects motion and attitude cues
Helps to provide balance
VISUAL SYSTEM
Vision
is the most reliable sense used
during flight
80% of orientation while flying is
dependent on the visual senses
THE CONDITION MOST
SUSCEPTIBLE TO SPATIAL
DISORIENTATION IS - During
a sudden and unexpected transition
from VMC to IMC flight conditions
VESTIBULAR SYSTEM
Semicircular
Canals
Otolith Organs
Semicircular Canals
Otolith Organs
Ossicles
Cochlea Auditory
Nerve
Ear Drum
Middle Ear
External Ear
Eustachian Tube
Opening to Throat
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
VISUAL TRACKING
Maintains focus of the retinal image
NYSTAGMUS
A rapid flickering motion of both
eyes back and forth, seriously
degrading visual acuity to 20/200
for a few seconds.
REFLEX INFORMATION
ORIENTATION WITHOUT
VISION
SEMICIRCULAR CANALS
Right
angles to each other
Contains endolymph fluid
FUNCTIONS OF THE
SEMICIRCULAR CANALS
Indicates Roll, Pitch, and Yaw
Change in both speed and direction
Responsive to angular acceleration and
deceleration
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)
FUNCTION OF THE OTOLITH ORGANS
UPRIGHT
TRUE SENSATION
TILT FORWARD
TRUE SENSATION
FORWARD ACCELERATION
FALSE SENSATION OF BACKWARD
TILT BACKWARD
TRUE SENSATION
CENTRIFUGAL /CENTIPUAL
FALSE SENSATION OF UPRIGHT
VESTIBULAR ILLUSIONS
Somatogyral
The Leans
Graveyard Spin
Coriolis
Somatogravic
Oculoagravic
Elevator
Oculogravic
THE LEANS
Most common form of Spatial Disorientation
Motion is usually undetected during a subthreshold
maneuver (less than 2o)
Pilot corrects attitude and compensates for the
false sensation of turning in the opposite direction
This illusion seldom affects both
pilots at the same time
Graveyard Spiral
THE CORIOLIS
ILLUSION
• The most deadly illusion
• Most likely to occur during an
instrument approach
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
SOMATOGRAVIC ILLUSION
Illusions created by the Otolith organs
as a result of linear acceleration
OCULOAGRAVIC
Upward movement of the eyes during
weightlessness, caused by rapid
downward motion of the aircraft
ELEVATOR ILLUSION
Occurs
during sudden upward
acceleration
Pilot perceives a nose up attitude
Tendency to “nose over” aircraft
UPRIGHT
EXTREME
AFT TILT
AFT TILT
UPRIGHT
OCULOGRAVIC ILLUSION
NOSE HIGH SENSATION
PROPRIOCEPTIVE
SYSTEM
SEAT OF PANTS FLYING
Very
unreliable means of orientation
Dependent upon gravity
Flying without reference to instruments
CLASSIFICATION OF
DISORIENTATION
TYPE I
- UNRECOGNIZED
TYPE II -
RECOGNIZED
TYPE III - INCAPACITATING
UNRECOGNIZED
Type I
Pilot
does not consciously perceive
any indication of Spatial
Disorientation
False inputs from sensory organs or
cues
Crashes with smile on their face
RECOGNIZED
Type II
Pilot
consciously perceives a problem,
but may not know it is due to spatial
disorientation
Pilot can correct the situation
INCAPACITATING
Type III
Pilot
experiences overwhelming
sensations
Conflict of sensory inputs
Unable to properly orient themselves by
use of instruments or visual cues
SPATIAL DISORIENTATION
Prevention techniques
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
PREVENTION (cont.)
Never
fly without visual reference points
Trust the instruments
Never stare at lights
Dark adaptation
Avoid self -imposed stresses (DEATH)
TREATMENT
Refer
to instruments
Develop and maintain cross-checks
Delay intuitive reactions
Transfer controls
ENSURE THE INSTRUMENTS
READ RIGHT !
Forward Acceleration