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!
QUESTIONS????