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Most of us wear sunglasses for one of two reasons: as a
fashion accessory that includes that certain
look or to help us see better in
bright sunlight. Sunglass choices are seemingly endless and can range
from
polarized goggles to colorful eye-catching tints on optical lens. Many sportsmen, including
golfers, recognize the significant contribution that polarized optics can provide to eye care and
performance enhancement.
For a moment let’s consider airplane pilots and how
sunglasses for them are much more than a mere
fashion statement. Sunglasses are
essential to safeguard a pilot's most important sense - their vision.
A quality
pair of sunglasses is standard equipment in every cockpit to optimize visual
performance.
They help reduce the harmful effects of sunlight glare, decrease
eye fatigue, and go a long way in
protecting the eye from exposure to UV radiation. Additionally, sunglasses protect
the pilot's eyes
from the potential mpact with objects such as flying debris
that can result from sudden
decompression or a daring aerobatic maneuver.
There are many choices of tints for sunglasses but the three
most common colors are gray,
gray-green, and brown. All of which are excellent choices
for the aviator. Gray is recommended the
most frequently as it tends to distort
the color of viewed objects the least. But many pilots prefer
gray-green and brown tints as they have been shown to enhance vividness and minimize scattered
blue and violet light. This enhances the
contrast in certain hazy conditions.
Important considerations for a pilot are sunglasses that
screen out only 70-85% of visible light and
not appreciably distort color. Any lenses
that block out more than 85% of visible light are not
recommended for pilots
due to the possibility of reduced visual acuity which in turn could result in
difficulty seeing the flight instruments and other data inside the cockpit in
certain low light conditions.
While polarized lenses are very popular, they are not
recommended for use by pilots. Polarized
optics are useful for blocking
reflected light from horizontal surfaces such as water or snow.
However,
polarization can also reduce the visibility of flight instruments that already incorporate
anti-glare filters.
Polarized sunglasses may also interfere with visibility
through an aircraft windscreen by emphasizing
the imperfections in the laminated
glass thereby masking the light reflected off of other aircrafts. In no
instances is it acceptable for a pilot
to reduce the ability see other aircraft.
Photo sensitive lenses automatically darken when exposed to
ultraviolet light and become lighter
when the conditions change to dim light.
The darkening takes place almost instantaneously, while the
lightening may take
several minutes. While most photo sensitive lenses can get as dark as regular
sunglasses, direct sunlight or temperatures above 70° Fahrenheit can seriously
limit their ability to
fully darken. Reduced ultraviolet light exposure in a
cockpit can further limit their effectiveness. As
photo sensitive lenses may
not be clear enough to be useful in low light conditions when flying in
clouds
or at night they are not recommended for pilots.
The selection of frames is more a matter of personal
preference; however, bayonet style temples are
the most popular because they
are easy to put on or remove while wearing headsets or a helmet.
Smaller lenses
may not be practical because they allow too much visible light and ultraviolet
radiation
to pass around the edges of the lenses. Finally, use of a neck strap
is recommended to prevent the
sunglasses from being accidentally dislodged.
While sunglasses are synonymous with the look of an aviator,
sunglasses are also one of the most
important pieces of equipment needed to
protect the pilot's eyes from bright sunlight and solar
radiation. Since
sunglasses are such an important asset, careful consideration should be taken
when selecting an appropriate pair to ensure many years of worry-free flying.
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