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Instrument Flying Handbook
Human factors
Sensory Systems for Orientation

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Instrument Flying


Table of Contents

Chapter 1. Human Factors
Chapter 2. Aerodynamic Factors
Chapter 3. Flight Instruments
Chapter 4. Section I
Airplane Attitude Instrument
Using Analog Instrumentation
Chapter 4. Section II
Airplane Attitude Instrument
Using an Electronic Flight

Chapter 5. Section I
Airplane Basic
Flight Maneuvers
Using Analog Instrumentation
Chapter 5. Section II
Airplane Basic
Flight Maneuvers
Using an Electronic Flight

Chapter 6. Helicopter
Attitude Instrument Flying

Chapter 7. Navigation Systems
Chapter 8. The National
Airspace System

Chapter 9. The Air Traffic
Control System

Chapter 10. IFR Flight
Chapter 11. Emergency

Isolating the orange square from surrounding influences
will reveal that it is actually brown. The application to a real
environment is evident when processing visual information
that is influenced by surroundings. The ability to pick out an
airport in varied terrain or another aircraft in a light haze are
examples of problems with interpretation that make vigilance
all the more necessary.

Figure 1-2 illustrates problems with perception. Both tables
are the same lengths. Objects are easily misinterpreted in
size to include both length and width. Being accustomed to
a 754 foot~wide runway on flat terrain is most likely going
to influence a pilot's perception of a wider runway on
uneven terrain simply because of the inherent processing

Vision Under Dim and Bright illumination
Under conditions of dim illumination, aeronautical charts and
aircraft instruments can become unreadable unless adequate
flight deck lighting is available. In darkness, vision becomes
more sensitive to light. This process is called dark adaptation.
Although exposure to total darkness for at least 30 minutes is
required for complete dark adaptation, a pilot can achieve a
moderate degree of dark adaptation within 20 minutes under
dim red flight deck lighting.

Red light distorts colors (filters the red spectrum), especially
on aeronautical charts, and makes it very difficult for the
eyes to focus on objects inside the aircraft. Pilots should
use it only where optimum outside night vision capability is
necessary. White flight deck lighting (dim lighting) should
be available when needed for map and instrument reading,
especially under IMC conditions.

Since any degree of dark adaptation is lost within a few
seconds of viewing a bright light, pilots should close one eye
when using a light to preserve some degree of night vision.
During night flights in the vicinity of lightning, flight deck
lights should be turned up to help prevent loss of night vision
due to the bright flashes. Dark adaptation is also impaired by
exposure to cabin pressure altitudes above 5,000 feet, carbon
monoxide inhaled through smoking, deficiency of Vitamin A
in the diet, and by prolonged, exposure to bright sunlight.

During flight iii visual meteorological conditions (VMC),
the eyes are the major orientation source and usually provide
accurate and reliable information. Visual cues usually
prevail over false sensations from other sensory systems.
When these visual cues are taken away, as they are in IMC,
false sensations can cause the pilot to quickly become

An effective way to counter these •false sensations is to
recognize die problem., disregard the false sensations, rely
on the flight instruments, and use the eyes to determine the
aircraft attitude. The pilot must have an understanding of
the problem and the skill to control the aircraft using only
instrument indications.

Shepard’s Tables.
Figure 1-2. Shepard's Tables.