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