Sunglasses are important protective devices for pilots. Sunglasses can reduce visual fatigue, thereby reducing the possibility of pilot error (Nakagawara & wood, 2009). A good pair of sunglasses can also protect the eyes and vision from ultraviolet (UV) radiation too.
So, there are many available varieties of sunglasses. But, how do you choose the right pair for flying? Note and avoid: Polarized lenses eliminate reflected glare from a flat surface. However, looking through a laminated aircraft windscreen, while wearing polarized lenses, can result in a reduced retinal image (Nakagawara & wood, 2009). Also, some windscreen of the aircraft is already polarized, hence polarized sunglasses result in double polarization.
(From the FAA regarding polarized glasses)
Polarized lenses are not recommended for use in the aviation environment. While useful for blocking reflected light from horizontal surfaces such as water or snow, polarization can reduce or eliminate the visibility of instruments that incorporate anti-glare filters. Polarized lenses may also interfere with visibility through an aircraft windscreen by enhancing striations in laminated materials and mask the sparkle of light that reflects off shiny surfaces such as another aircraft’s wing or windscreen, which can reduce the time a pilot has to react in a “see-and-avoid” traffic situation. (Airliners.net, 2009)
FAA publication: Sunglasses for pilots: beyond the image. http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/sunglasses.pdf
FAA pilot safety brochure: Pilot vision. http://www.faa.gov/pilots/safety/pilotsafetybrochures/media/Pilot_Vision.pdf
Nakagawara, V.B. & wood, K.J. (2009). Not All Sunglasses Are Created Equal. Retrieved 2 Oct, 2009 from http://www.aoa.org/x5349.xml
Airliners.net. (2009). Forum. Retrieved 1 Oct, 2009 from