Visual Illusions

Question 1

Visual References

Answer 1

● Interposition of known objects.
➢ One object placed in front of another is perceived as being closer to the observer.
● Varying texture or contrast of known objects at different distances.
➢ Object detail and contrast are lost with distance.
● Differences in illumination perspective of objects due to light and shadows.

Narrow Runway
● A final approach to an unusually narrow runway or an unusually long runway may produce the visual illusion of a high-altitude final approach

A downsloping runway can create the illusion that the aircraft is lower than it actually is, leading to a higher approach.

Question 2

Black Hole Approach

Answer 2

● A Black-Hole Approach Illusion can happen during a final approach at night (no stars or moonlight), over water, or unlighted terrain to a lighted runway beyond which the horizon is not visible

● A particularly hazardous black-hole illusion involves approaching a runway under conditions with no lights before the runway environment and with city lights or rising terrain beyond the runway.
➢ These conditions may produce the visual illusion of a high altitude final approach

Autokinetic Illusion
● Gives you the impression that a stationary object is moving in front of the aircraft’s path.
○ It is caused by staring at a fixed single point of light (ground light or a star) in a totally dark and featureless background.
● This illusion can cause a misperception that such a light is on a collision course with your aircraft.

Question 3

False Visual Reference Illusions

Answer 3

● These illusions can be caused by flying over a banked cloud.
● Mountainous terrain can also cause us to fall for a false horizon!
● Night flying over featureless terrain with ground lights that are indistinguishable from a dark sky with stars can cause false visual reference also.

Rain on Windscreen
● Illusions caused by rain on the windscreen can cause the pilot to think they are higher than actually are.
● A runway may appear shorter.
● Things may appear to be farther away.
● Approach lights appear lower.
● In general you seem higher and farther away.

Question 4

Vection Illusion

Answer 4

● An illusion that may be present when taxiing an aircraft.
● The brain perceives peripheral motion and applies it to the aircraft the pilot is currently sitting in.
● Another nearby aircraft that is moving may make the pilot feel as though their plane is moving instead

White Out
● It is a weather condition that causes disorientation and low visibility by snow, overcast cloud and fog.
● The horizon disappears from view while the sky and landscape appear featureless, leaving no points of visual reference.
● The perception of depth and the evaluation of distances are likely to be reduced, although visibility does not seem to be reduced