Fixed format liquid crystal display readability in bright ambient environments

The readability of fixed-format, liquid crystal displays in flight deck installations has recently become a subject of industry wide comment and discussion. Pilots have stated that LCDs mounted in flight deck instruments and control panels present inadequate readability levels when viewed in bright ambient environments. To better understand the relationships between display character legibility and key display parameters, a human subject evaluation was performed simulating daylight cockpit environments. The study varied character luminance and display contrast in several ambient environments, including very bright forward fields, to determine their effect on display recognition response speed and error rates. The results showed monotonically decreasing response time with increasing character luminance. The data also show that for the numeric displays used, a response time of around one second could be achieved with a total character luminance of 50 to 55 foot lamberts