The relationship between aviation accidents and sunglasses was examined in a report published by the Federal Aviation Administration (FAA) in July of 2001 concerning the use of ophthalmic devices (glasses) by civilian pilots. The study reviewed data for the period 1988 through 1998 and found 16 events in which the use of glasses (including sunglasses) were a contributing factor to the mishap. The study concluded that indeed the use of ophthalmic devices had contributed to aviation accidents and incidents. The FAA determined that the use of glasses of any kind could reduce the field of vision, be incompatible with headsets and protective breathing equipment like oxygen masks. Eyeglass frames that are ill-fitting can cause physical discomfort or become displaced during flight maneuvers due to centrifugal or gravitational forces. The use of contact lenses also creates a problem because of the relatively low humidity in an aircraft cockpit combined with changes in barometric pressure due to altitude changes. Approximately half of civilian pilots wear glasses to correct their vision and maintain a current airman medical certificate. The Federal Aviation Administration (FAA) authorized a study to determine the relationship between aviation accidents and incidents associated with the use of glasses, including sunglasses. For the period studied (1-1-80 to 12-31-98) there were 40,476 accidents and 1,497 incidents reported to the FAA of which 15 accidents where the use of ophthalmic devices was considered a contributing factor. As you can see by the table above the lack or misuse of sunglasses was a contributing factor to aviation accidents and incidents, and as a result the FAA made the following recommendations regarding the use of sunglasses while flying: Pilots often need sunglasses when flying during daylight hours. Tinted lenses can reduce glare, visual fatigue, and dark adaptation problems later in the flight. However, sunglasses can compromise the readability of aircraft instruments and other aviation materials, such as charts and maps, inside the cockpit. This study found that improper use or not using sunglasses contributed to one aviation accident and six incidents. When using sunglasses, a proper balance should be maintained between visibility of objects inside and outside the cockpit environment. Sunglasses that distort color, such as “yellow-shooters” and “blue-blockers,” or those that prevent the transmission of too much light (i.e., < 15% transmission) should be avoided (2). Polaroid sunglasses are not recommended since they can reduce or effectively eliminate the visibility of instruments that incorporate anti-glare filters, or they can interfere with visibility through an aircraft windscreen due to striations in some laminated materials (12). In addition, polaroid sunglasses can mask the sparkle of light that reflects off shiny surfaces, such as another aircraft’s wing or windscreen. This could drastically reduce a pilot’s reaction time in a “see-and-avoid” traffic situation. To improve aviation safety, the following recommendations concerning the use of ophthalmic devices are offered to Aviation Medical Examiners (AMEs), pilots, and their eye care practitioners:
- Eyeglasses should fit snugly on the head to prevent being dislodged. A spectacle strap that fits tightly around the head or a spectacle chain that allows the eyeglasses to be easily replaced if dislodged should be used while flying;
- All screws on the spectacle frame should be tight and ophthalmic lenses should fit snugly in the frame to prevent a lens from being dislodged. A back-up pair of eyeglasses should be readily available for the pilot in the event spectacles are damaged or displaced in flight;
- An appropriate pair of sunglasses should be readily available during daylight flying to prevent glare or temporary flash blindness. Sunglasses should not be worn in low-light conditions.