7 Visual Illusions To Be Prepared For On Your Next Flight

7 quick ways to get in trouble…

1) Runway Width

If you normally train at an airport with a 100-200′ wide runway, flying into an airport with a 50′ wide runway will cause your sight picture to look a lot different. The normal reaction to this illusion is flying a lower approach on a narrow runway, because it looks like you’re above glide path. And if you go too low, you can get dangerously close to obstacles.

2) Black Hole Approach

Our bodies use peripheral vision to orient ourselves in space. When you are approaching an airport at night that has few lights or ground features, you find yourself in a black hole approach.

This gives you the illusion that you’re higher than you actually are, because the airport looks like an island of bright lights with nothing but darkness around it.

Pilots tend to fly lower approaches into these kinds of airports, hence the name “black hole effect”. The darkness sucks you in, and if you aren’t careful, can cause you to crash short of the runway.

3) Somatogyral Illusion

Your body is unable to detect angular motion less than 3 degrees per second. In IMC, if you were to unknowingly bank the aircraft to the left or right and maintain it for 20 seconds or more, you set yourself up for the oculogyric illusion. Because your body perceives your banked attitude to be straight-and-level, correcting the bank back to straight-and-level would feel like you’ve initiated a bank in the opposite direction. Having this happen in areas with a terrain or close to the ground could be lethal.

4) Elevator Illusion

The elevator illusion occurs when you are in IMC and experience a sudden updraft. This causes the aircraft to move up and your eyes to move down, creating the illusion that you have pitched up. The common reaction to this illusion is to push forward on the control wheel. This causes you to start a descent, creating an extreme hazard, especially if you are low to the ground or near terrain.

5) Graveyard Spin

A spin in IMC with no visual references for more than 20 seconds will cause your body’s vestibular system to fail to detect the aircraft’s rotational motion. Because of this, recovering from the spin will cause you to feel as if you have entered a spin in the opposite direction. The danger of this illusion lies in the fact that putting in wrong rudder inputs can actually tighten the spin and delay recovery even further.

6) Coriolis Illusion

The Coriolis illusion, caused by undetected motion in a standard rate turn, happens when the movement of fluid in the semicircular canals is different than what’s perceived. When the fluid equalizes in a standard rate turn, reaching down to pick up a pen or looking to your right to check on a passenger causes the fluid to move, creating a tumbling sensation. This can cause you to over-control the plane and potentially put it into an unusual attitude.

7) Sloping Runway

Similar to runway width, a sloping runway can cause sight picture issues on final. A runway that slopes up creates the illusion of being too high, so you subconsciously fly a lower approach. Like the runway width illusion, this can put you dangerously close to terrain and obstacles on final.