Aeromedical: Spatial Disorientation Flashcards
SPATIAL DISORIENTATION (SD)
Spatial disorientation is an individuals inability to determine his position, attitude, & motion relative to the surface of the earth, or significant objects. Ie..trees, poles, or building during a hover.
When it occurs, pilots are unable to see, believe, interpret, or prove the information derived from their flight instruments.
Sensory Illusion.
is a false perception of reality caused by a conflict of orientation information from one or more mechanisms of equilibrium.
Sensory illusions are a major cause of Spatial Disorientation.
Vertigo.
is a spinning sensation usually caused by a peripheral vestibular abnormality in the middle ear.
Pilots often misuse the term vertigo, applying it generically to all forms of spatial disorientation.
TYPES OF SPATIAL DISORIENTATION
TYPE I. (UNRECOGNIZED)
TYPE II (RECOGNIZED)
TYPE III (INCAPACITATING)
TYPES OF SPATIAL DISORIENTATION:
TYPE I. (UNRECOGNIZED)
THE MOST DANGEROUS TYPE
A disoriented aviator does not perceive any indication of spatial disorientation, he does not think anything is wrong. -because he fails to recognize or correct the disorientation, usually resulting in a crash.
SD would be height-/depth perception illusion when the pilot descends into the ground or some obstacle because of UNRECOGNIZED SD
TYPES OF SPATIAL DISORIENTATION:
TYPE II (RECOGNIZED)
The pilot perceives a problem (resulting from SD).
- may fail to recognize it as SD.
- may feel that a control is malfunctioning.
- may perceive an instrument failure as in a graveyard spiral.
TYPES OF SPATIAL DISORIENTATION:
TYPE III (INCAPACITATING)
The pilot experiences such an overwhelming sensation of movement that he cannot orient himself by using visual cues or the aircraft’s instruments.
Not fatal if pilot can gain control of the aircraft.
EQUILIBRIUM MAINTENANCE: Visual System
is the most important in maintaining equilibrium & orientation. 80% of our orientation information comes from the visual system.
IMC-must rely on instruments for Spatial Orientation. Demands disciplined training.
EQUILIBRIUM MAINTENANCE: Vestibular System.
Inner ear contains the vestibular system, which contains the motion- & gravity detecting sense organs.
Located in the temporal bone on each side of the head. Each vestibular consist of 2 distinct structures; semicircular canals / vestibule proper, which contain the otolith organs.
Vestibule Proper.
The otolith organs are small sacs located in the vestibule.
Sensory hairs project from each macula into the otolithic membrane, an overlaying gelatinous membrane that contains chalklike crystals, called otoliths. They respond to gravity & linear accelerations/decelerations.
Changes in position of the head, relative to the gravitational force, cause the otlithic membrane to shift position on the macula. The sensory hairs bend, signaling a change in head position.
Semicircular Canals.
- They sense changes in an angular acceleration.
- The canals will react to any changes in roll, pitch, or yaw attitude.
- The endolymph fluid in the canals move with inertial torque resulting from angular acceleration in one of three planes.
- This movement stimulates the vestibular nerve & these impulses are transmitted to the brain where they are interpreted as rotation of the head
Equilibrium Systems
- Visual
- Vestibular
- Proprioceptive - Body Orientation & Balance
Proprioceptive System.
- The systems reacts to the sensation resulting from pressures on joints, muscles, & skin & from slight changes in the position of internal organs.
- Forces act upon the seated pilot in flight.
