VISION
We obtain most of our orientation through our vision The majority of visual orientation is good but there are some flaws especially when we do not have adequate reference points
CONES
• • Concentrated at the fovea They are useful for detecting color, fine detail, and during high illumination, (photopic vision)
•
•
When exposed to low levels of illumination, cones produce iodopsin.
Flaws are:
• • • • Blind spots Night vision limitations Visual illusions (false horizon, autokinesis) Optical illusions
COMPONENTS OF THE EYE
RODS
• • • • • • Used during low levels of light, (scotopic vision) Found along the retina; used for peripheral vision. Not effective for detecting color or detail. Produce rhodopsin using oxygen. Rhodopsin bleaches quickly if exposed to light There are approximately 20 to 30 times more rods than cones
Sensory Systems for orientation Illusions in flight Physiological and psychological factors Medical factors Aeronautical decision making (ADM) Crew Resource management (CRM) and Single Pilot Resource Management (SRM)
OPTICAL ILLUSIONS

OPTICAL ILLUSIONS
OPTICAL ILLUSIONS
Runway Width illusion Runway and Terrain Slopes Illusion Featureless Terrain Illusion Water Refraction Haze Fog Ground Lighting Illusions
EARS
ILLUSIONS LEADING TO SPATIAL DISORIENTATION
Besides the visual illusions caused by the human eye sight. The sensory system responsible for most of the illusions leading to spatial disorientation is the vestibular system.
CORIOLIS ILLUSION
when a pilot has been in a turn long enough for the fluid in the ear canal to move at the same speed as the canal. A movement of the head in a different plane, such as looking at something in a different part of the flight deck, may set the fluid moving and create the illusion of turning or accelerating on an entirely different axis.
VISUAL ILLUSIONS
False Horizon A sloping cloud formation, an obscured horizon, an aurora borealis, a dark scene spread with ground lights and stars, and certain geometric patterns of ground lights can provide inaccurate visual information, or false horizon, for aligning the aircraft correctly with the actual horizon. The disoriented pilot may place the aircraft in a dangerous attitude. Autokinesis In the dark, a stationary light will appear to move about when stared at for many seconds. The disoriented pilot could lose control of the aircraft in attempting to align it with the false movements of this light, called autokinesis.
PREPARING FOR NIGHT FLIGHT
Avoid bright white light for 30 minutes Preflight using a dim light If you are exposed to a bright light, close one eye to avoid ruining night vision in both eyes Avoid using red lights, as red on the charts will not show up.
Iodopsin makes the cones 100X more sensitive to light
BLIND SPOTS
SCAN TECHNIQUES
• • As you scan, do not scan more than 10 degrees at time. Focus on the area for at least 1 second and allow 1 second for your eyes to focus on the new location.
SOMATOGRAVIC ILLUSION
A rapid acceleration, such as experienced during takeoff, stimulates the otolith organs in the same way as tilting the head backwards. This action creates the somatogravic illusion of being in a nose-up attitude
HUMAN FACTORS
THE ELEMENTS AFFECTING HUMAN INTERACTION WITH OTHER PEOPLE, MACHINES, AND THE ENVIRONMENT THEY ENCOUNTER
ELEMENTS COVERED IN THIS CHAPTER
SENSORY SYSTEMS FOR ORIENTATION
Eyes - maintain visual orientation Ears – motion sensing maintains vestibular orientation Nerves – located throughout the body in the skin, joints, and muscles to maintain postural orientation When conflicting information comes from these 3 systems we become disoriented
•
• • •
For night operations, use off center/peripherals in order to utilize rods
At night don’t focus on an object as it will fade due to autokinesis Scanning continuously to expose new areas of the retina to the light. Develop your scan
Vestibular Illusions The Leans Coriolis Illusion Graveyard Spiral Somatogravic Illusion Inversioin Illusion Elevator Illusion
THE LEANS
when a banked attitude, to the left for example, may be entered too slowly to set in motion the fluid in the ―roll‖ semicircular tubes. An abrupt correction of this attitude sets the fluid in motion, creating the illusion of a banked attitude to the right. The disoriented pilot may make the error of rolling the aircraft into the original left banked attitude, or if level flight is maintained, will feel compelled to lean in the perceived vertical plane until this illusion subsides.