VISUAL ILLUSIONS SSG RODRIGUEZ REFERENCES: FM 1-301, TC 1-204
VISUAL ILLUSIONS The purpose of this class is to give aircrew members the understanding of the illusions and disorientation that can be experienced while flying. Even with references outside the cockpit and the display of instruments inside, aircrew members must be aware and interpret information correctly.
VISUAL ILLUSIONS Decreasing visual information increases the provability of spatial disorientation. Reduced visual reference also create several illusions that can induce spatial disorientation. The acronym that will help you remember the visual illusions is: F.F.F. C.R.A.S.H. S.A.R.
VISUAL ILLUSIONS FASCINATION (FIXATION): Occurs when crew ignore orientation cues and focus their attention on their object and goals. Target hypnosis is a common type of fascination. When a pilot intents to hit a target during gunnery run, the pilot may delay pull-up so long that the aircraft may hit the ground. Increasing scanning techniques will help avoid this illusion.
VISUAL ILLUSIONS FLICKER VERTIGO: A light flickering at a rate of 4 to 20 cycles per sec. Nausea and vomiting in mild cases will occur. In severe cases convulsions and unconsciousness can be experienced. Fatigue, frustration and boredom tent to add to this problem. During the day, the sunlight flickering through the rotor blades will create this effect. During the night, anti-collision lights reflecting against overcast sky, haze, or the rotor system. Proper scanning techniques will decrease focusing on the flickering.
VISUAL ILLUSIONS FALSE HORIZON: Cloud formations may be confused with the horizon on the ground. Confusion may result when a crewmember looks up after being focused inside the cockpit for an extended period of time. Outside references for attitude are less obvious and reliable at night. Pilots should cross reference with instruments.
VISUAL ILLUSIONS CONFUSION WITH GROUND LIGHTS: At night, pilots can put the aircraft in very unusual attitudes to keep ground lights above them. They can mistake the ground lights for the horizon and seashore lights with stars. This cause the pilots to maneuver close to the sea or ground. Cross reference with instruments will help this illusion.
VISUAL ILLUSIONS REVERSIBLE PERSPECTIVE : At night, an aircraft may appear to be going away when is actually approaching. This occurs when one aircraft is flying parallel to another. Watch for the lights, if the are increasing in size the aircraft is coming at you and if they are decreasing is going away from you. A key to remember is: If the red position light is on the RIGHT, the aircraft is RETURNING. RED, RIGHT, RETURN.
VISUAL ILLUSIONS AUTOKINESIS: When you stare at a static light in the dark, the light appears to move. If you take a lighted cigarette in a dark room, movement will begin in about 8 to 10 seconds. Your eyes are trying to find another visual reference point. This illusion is not limited to the darkness, it can happen at any time. Correct scanning is the most important solution to this problem. You should not stare at any object or light for more than 10 seconds.
VISUAL ILLUSIONS SIZE-DISTANCE ILLUSION: This results from viewing a light that increases and decreases in brightness. At night, an aircraft hovers next to your aircraft and turns the lights from dim to bright. The aircraft will appear to jump closer to you when it is in the same position. Awareness of the aircraft’s position and proper scanning techniques will help you to determine if the aircraft is in fact moving closer to you.
VISUAL ILLUSIONS HEIGHT PERCEPTION ILLUSION: It is the feeling of being higher above the terrain than you really are. The lack of visual references in areas of poor contrast such as snow, water, or the desert will give you this illusion. Monitor the shadow cast by near objects, such as landing gear, or the aircraft shadow at a hover.
VISUAL ILLUSIONS STRUCTURAL ILLUSION: Caused by things that obscure the vision such as rain showers, heat waves, snow, or sleet. A straight line may appear to be curved when viewed in a desert heat wave, or through a “bubble” window. Be aware of the illusion and your surroundings and change the perspective of view to determine the object that you are trying to identify.
VISUAL ILLUSIONS ALTERED PLAINS OF REFERENCE: A sense of feeling that the pilot needs to climb when the altitude is adequate for crossing an obstacle. When flying over mountains, the pilots may feel the need to climb in altitude when they are well cleared of the mountains. Cross reference with the altimeters and altimeter settings and knowing the altitude of the object will help with this illusion.
VISUAL ILLUSIONS RELATIVE MOTION: This illusion is often encountered during a formation flight when pilots see the movement of other aircraft in their peripheral vision and interpret it as their own motion. Hovering over high grassy areas and focusing on the movement of the grass will give them a sense of aircraft movement. Proper scanning and use of reference points to include the members on the back calling the drifting of the aircraft will help with this illusion.
VISUAL ILLUSIONS In conclusion, this class will give you the fundamental understanding of this illusions. It will take time and careful reviewing of your notes and books to get a full grasp of this illusions. You should review this at least once a week or before a day or night flight. Be aware of this illusions and recognize them as soon as they appear. If you need help, ask another crewmember to clarify what you are seeing. Always call it as you see it!