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Human Performance

2.5.1.5 Eye diseases

When we are young, the lens is soft and flexible. With age, it becomes harder,

and reading glasses may be required. The lens can also become cloudy, leading

to cataracts.

Another condition is glaucoma, caused by increased pressure inside the eye.

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2.5.2 Approach illusions

Here are some other examples of illusions related to approach.

When approaching a runway that is narrower than the one you are used to, you

will think that you are too high. As a result, you will make an approach that is

too low.

Other illusions:

If a cloud suddenly obscures the runway during approach, pilots may tend to

descend to regain visual contact, potentially leading to a dangerous low

approach. Runway or terrain slopes upwards Higher altitude Lower approach

Here is a chart of approach illusions.

Approach Illusions

SITUATION ILLUSION RESULT

Runway or terrain slopes upwards Higher Altitude Lower Approach

Lane narrower than usual Higher Altitude Lower Approach
Deserted terrain (Black–hole night flight) Higher Altitude Lower Approach

Course or terrain slopes downwards Less Height Higher Approach

Lane wider than usual Less Height Higher Approach
Powerful runway and approach lights Less Distance Higher Approach

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 156