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Pilot's Handbook of Aeronautical Knowledge
Aeromedical Factors

Health and Physiological Factors Affecting Pilot Performance

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Pilot's Handbook of Aeronautical Knowledge



Table of Contents

Chapter 1, Introduction To Flying
Chapter 2, Aircraft Structure
Chapter 3, Principles of Flight
Chapter 4, Aerodynamics of Flight
Chapter 5, Flight Controls
Chapter 6, Aircraft Systems
Chapter 7, Flight Instruments
Chapter 8, Flight Manuals and Other Documents
Chapter 9, Weight and Balance
Chapter 10, Aircraft Performance
Chapter 11, Weather Theory
Chapter 12, Aviation Weather Services
Chapter 13, Airport Operation
Chapter 14, Airspace
Chapter 15, Navigation
Chapter 16, Aeromedical Factors
Chapter 17, Aeronautical Decision Making




Coping with Spatial Disorientation
To prevent illusions and their potentially disastrous
consequences, pilots can:

1. Understand the causes of these illusions and remain
constantly alert for them. Take the opportunity to
experience spatial disorientation illusions in a device
such as a Barany chair, a Vertigon, or a Virtual Reality
Spatial Disorientation Demonstrator.
2. Always obtain and understand preflight weather
3. Before flying in marginal visibility (less than 3 miles)
or where a visible horizon is not evident, such as flight
over open water during the night, obtain training and
maintain proficiency in airplane control by reference
to instruments.
4. Do not continue flight into adverse weather conditions
or into dusk or darkness unless proficient in the use of
flight instruments. If intending to .y at night, maintain
night flight currency and proficiency. Include cross-country
and local operations at various airfields
5. Ensure that when outside visual references are used,
they are reliable, .xed points on the Earth's surface.
6. Avoid sudden head movement, particularly during
takeoffs, turns, and approaches to landing.
7. Be physically tuned for flight into reduced visibility.
That is, ensure proper rest, adequate diet, and, if flying
at night, allow for night adaptation Remember that
illness, medication, alcohol, fatigue, sleep loss, and
mild hypoxia are likely to increase susceptibility to
spatial disorientation.
8. Most importantly, become proficient in the use of
flight instruments and rely upon them. Trust the
instruments and disregard your sensory perceptions.

The sensations that lead to illusions during instrument
flight conditions are normal perceptions experienced by
pilots. These undesirable sensations cannot be completely
prevented, but through training and awareness, pilots can
ignore or suppress them by developing absolute reliance
on the flight instruments. As pilots gain proficiency in
instrument flying, they become less susceptible to these
illusions and their effects.

Optical Illusions
Of the senses, vision is the most important for safe flight
However, various terrain features and atmospheric conditions
can create optical illusions. These illusions are primarily
associated with landing. Since pilots must transition from
reliance on instruments to visual cues outside the flight deck for
landing at the end of an instrument approach, it is imperative
they be aware of the potential problems associated with these
illusions, and take appropriate corrective action. The major
illusions leading to landing errors are described below.

Runway Width Illusion
A narrower-than-usual runway can create an illusion the
aircraft is at a higher altitude than it actually is, especially
when runway length-to-width relationships are comparable.
[Figure 16-7] The pilot who does not recognize this illusion
will .y a lower approach, with the risk of striking objects
along the approach path or landing short. A wider-than usual
runway can have the opposite effect, with the risk of
the pilot leveling out the aircraft high and landing hard, or
overshooting the runway.

Runway and Terrain Slopes Illusion
An upsloping runway, upsloping terrain, or both, can create
an illusion that the aircraft is at a higher altitude than it
actually is. [Figure 16-7] The pilot who does not recognize
this illusion will .y a lower approach. Downsloping runways
and downsloping approach terrain can have the opposite

Featureless Terrain Illusion
An absence of surrounding ground features, as in an
over water approach, over darkened areas, or terrain made
featureless by snow, can create an illusion the aircraft is at
a higher altitude than it actually is. This illusion, sometimes
referred to as the "black hole approach," causes pilots to .y
a lower approach than is 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.

Atmospheric haze can create an illusion of being at a greater
distance and height from the runway. As a result, the pilot
will have a tendency to be low on the approach. Conversely,
extremely clear air (clear bright conditions of a high attitude
airport) can give the pilot the illusion of being closer than he
or she actually is, resulting in a high approach, which may
result in an overshoot or go around. The diffusion of light
due to water particles on the windshield can adversely affect
depth perception. The lights and terrain features normally
used to gauge height during landing become less effective
for the pilot.

Flying into fog can create an illusion of pitching up. Pilots
who do not recognize this illusion will often steepen the
approach quite abruptly.

Ground Lighting Illusions
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 of less distance to the runway. The pilot who does not
recognize this illusion will often fly a higher approach.