Illusions Flashcards
False Horizon
An illusion in which the pilot may misidentify the horizon line. May be caused by sloping cloud formation,
an obscured horizon, an aurora borealis, dark night with scattered lights and stars or the geometry of the ground
Autokinesis
Staring at a stationary point of light in a dark or featureless scene for a prolonged period of time may cause
the light to appear to be moving. A pilot may attempt to align the aircraft with the perceived moving light, resulting in loss of
control.
Runway Width Illusion
narrow runway may create the illusion that the aircraft is higher than it actually is. A wide
runway may cause the opposite effect of the aircraft flying too low.
Runway and Terrain Slope Illusion
An upsloping terrain or runway may create the illusion that the aircraft is at a higher
altitude than it actually is.
Featureless Terrain Illusion
Also known as “black hole approach.” Flying over featureless or dark areas, such as in an overwater approach, can create the illusion that the aircraft is at a higher altitude than it actually is and may lead the pilot to fly at a lower altitude than desired.
Water Refraction
Rain on the windscreen can create an illusion of being at a higher altitude due to the horizon appearing lower than it is. This can result in the pilot flying a lower approach.
Haze
Shooting an approach in haze may create the illusion that the runway is further that it actually is, or that the aircraft is higher than it actually is.
Fog
Flying into fog may create an illusion of a nose-up motion.
Ground Lighting Illusion
Lights along a straight path, such as a road or lights on moving trains, can be mistaken for
runway and approach lights. Bright runway and approach lighting systems, especially where few lights illuminate the
surrounding terrain, may create the illusion that the runway is closer than it actually is. This may result in the pilot flying a
higher approach than desired.
The Leans
After leveling the wings following a prolonged turn, pilot may feel that the aircraft is banked in the opposite
direction of the turn.
Coriolis Illusion
After a prolonged turn, the fluid in the ear canal moves at same speed as the canal. A head movement on a different plane will cause the fluid to start moving and result in a false sensation of acceleration or turning on a different axis.
Graveyard Spiral
A pilot in a prolonged, coordinated constant-rate turn may experience the illusion of not turning. After leveling the wings, the pilot may feel the sensation of turning to the other direction (“the leans”), causing the pilot to turn back in the original direction. Since a higher angle of attack is required during a turn to remain level, the pilot may notice a loss of altitude and apply back force on the elevator. This may tighten the spiral and increase the loss of altitude.
Somatogravic Illusion
Rapid acceleration stimulates the inner ear otolith organs in the same way as tilting the head backwards. This may create the illusion of a higher pitch angle. Deceleration causes the opposite illusion – the sensation of tilting the head forward and the aircraft being in a nose-low attitude.
Inversion Illusion
An abrupt change from climb to straight and level may create the illusion of tumbling backwards due to the fluid movement in the otolith organs.
Elevator Illusion
An abrupt upward vertical acceleration may create the illusion of climbing, due to fluid movement in the otolith organs.
