VISUAL ILLUSIONS Flashcards
FASCINATION/FIXATION
Fascination or fixation in flying can be separated into two categories: task saturation and target fixation. Task saturation occurs when crewmembers become so engrossed with a problem or task within the cockpit they fail to properly scan outside the aircraft. Target fixation, commonly referred to as target hypnosis, occurs when crewmembers ignore orientation cues and focus their attention on an object or goal.
FALSE HORIZON
False horizon illusions occur when a pilot confuses cloud formations with the horizon or ground. A sloping cloud deck can be difficult to perceive as anything but horizontal if it extends any great distance in the pilot’s peripheral vision.
FLICKER VERTIGO
Flicker vertigo is not technically an illusion. However, as most people are aware from personal experience, viewing a flickering light can be both distracting and annoying. Flicker vertigo is created by helicopter rotor blades or airplane propellers interrupting direct sunlight at a rate of 4 to 20 cycles per second.
CRATER ILLUSION
Crater illusions occur when crewmembers land at night under night vision device (NVD) conditions and the infrared searchlight is directed too far under the aircraft’s nose. This combination creates the illusion of landing with upsloping terrain in all directions or landing in a crater.
RELATIVE MOTION
Relative motion is falsely perceived self-motion in relation to another object’s motion. The most common example is when an individual in a car is stopped at a traffic light and another car pulls alongside.
AUTOKINESIS
Autokinesis occurs primarily at night when ambient visual cues are minimal and a small, dim light is seen against a dark background. After about 6 to 12 seconds of visually fixating on the light, an individual perceives movement at up to 20 degrees in any particular direction or in several directions in succession, although there is no actual object displacement.
SIZE-DISTANCE
Size-distance illusions are false perceptions of distance from an object or the ground, created when a crewmember misinterprets an unfamiliar object’s size to be the same as an object they are accustomed to viewing.
HIGHT-DEPTH
Height-depth perception illusions are due to a lack of sufficient visual cues and causes crewmembers to lose their depth perception. Flying over areas devoid of visual references such as desert, snow, or water deprives crewmembers their perception of height.
CONFUSION WITH GROUND LIGHTS
Confusion with ground lights occurs when a pilot mistakes ground lights for celestial lights. The illusion prompts the pilot to place the aircraft in an unusual attitude to keep the misperceived ground lights above the aircraft.
STRUCTURAL ILLUSION
Structural illusions are caused by the effects of rain, snow, sleet, heat waves, or other visual obscurants. A straight line can appear curved when viewed through heat waves in the desert. A single wingtip light might appear as a double light or in a different location when viewed through rain.
ALTERED PLANES OF REFERENCE
Altered planes of reference create an inaccurate sense of altitude, attitude, or flight path position in relation to an object so great in size it replaces the horizon as the plane of reference.
REVERSIBLE PERSPECTIVE
Reversible perspective illusions occur at night when a crewmember perceives another aircraft to be moving away as it is actually approaching.
