FAA Office of Aerospace Medicine
Civil Aerospace Medical Institute

Report No: DOT/FAA/AM-03/6

Title and Subtitle: Natural Sunlight and Its Association to Aviation Accidents: Frequency and Prevention

Report Date: May 2003

Authors: Nakagawara VB, Wood KJ, and Montgomery RW

Abstract:
Introduction. Glare is a temporary visual sensation produced by luminance (brightness) within the visual field that is significantly greater than that to which the eyes are adapted. Aviators may be subjected to intense glare from natural and artificial light sources that can result in temporary visual impairment, greatly increasing the risk of accidents. The purpose of this study was to investigate the relationship between visual impairment from natural sunlight and aviation accidents.

Methods. The National Transportation Safety Board Aviation Accident/Incident Database was queried for the period 1/1/1988 to 12/31/1998 for terms related to glare including sun, glare, vision, blinded, and reflections. All reports annotated with one or more of these terms were reviewed to determine whether glare from natural sunlight was considered a direct or contributing factor in the aviation accident. Accidents that did not involve the pilot-in-command of an air transport or general aviation aircraft were omitted.

Results. For the study period, there were 130 accidents in which glare from natural sunlight was found to be a contributing factor. The majority of the events occurred during clear weather and atmospheric conditions (85%), and were associated with approach/landing and takeoff/departure phases of flight (55%).

Conclusions. Exposure to glare from natural sunlight has contributed to aviation accidents, primarily under optimal visual conditions. The majority of accidents occurred during flight maneuvers at low altitude in airspace congested with other aircraft or obstacles, such as trees, power lines, utility poles, and terrain. Preventative techniques are presented that may protect a pilot's visual performance against the debilitating effects of glare from the sun.

Key Words: Aviation Vision; Accident Risk; Glare; Visual Impairment; Afterimage; Flashblindness

No. of Pages: 8