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Pilot's Handbook of Aeronautical Knowledge
Aeromedical Factors

Vision in Flight

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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




The human eye.
Figure 16-12. The human eye.

To avoid the bends, scuba divers must not fly for specific time periods following dives.
Figure 16-11. To avoid the bends, scuba divers must not fly for
specific time periods following dives.

The recommended waiting time before going to flight
altitudes of up to 8,000 feet is at least 12 hours after diving
that does not require controlled ascent (non decompression
stop diving), and at least 24 hours after diving that does
require controlled ascent (decompression stop diving). The
waiting time before going to flight altitudes above 8,000
feet should be at least 24 hours after any scuba dive. These
recommended altitudes are actual flight altitudes above mean
sea level (AMSL) and not pressurized cabin altitudes. This
takes into consideration the risk of decompression of the
aircraft during flight

Vision in Flight

Of all the senses, vision is the most important for safe flight
Most of the things perceived while flying are visual or heavily
supplemented by vision. As remarkable and vital as it is,
vision is subject to limitations, such as illusions and blind
spots. The more a pilot understands about the eyes and how
they function, the easier it is to use vision effectively and
compensate for potential problems.

The eye functions much like a camera. Its structure includes
an aperture, a lens, a mechanism for focusing, and a surface
for registering images. Light enters through the cornea at the
front of the eyeball, travels through the lens, and falls on the
retina. The retina contains light sensitive cells that convert
light energy into electrical impulses that travel through nerves
to the brain. The brain interprets the electrical signals to form
images. There are two kinds of light-sensitive cells in the
eyes: rods and cones. [Figure 16-12]

The cones are responsible for all color vision, from
appreciating a glorious sunset to discerning the subtle shades
in a .ne painting. Cones are present throughout the retina, but
are concentrated toward the center of the field of vision at the
back of the retina. There is a small pit called the fovea where
almost all the light sensing cells are cones. This is the area
where most "looking" occurs (the center of the visual field
where detail, color sensitivity, and resolution are highest).