Ishihara colour test et al
The Ishihara test is generally used to determine gross errors such as red/green colour blindness. Some might question why red & green signals are used on roads almost universally, and indeed on British railways. Interestingly French railways use cyan/magenta signals.
I am unaware how precise colour vision needs to be for commercial pilot, but for those who require "perfect" colour vision a chromaticity test is normally used. This involves arranging a large number of coloured pegs or balls in ranks corresponding to their hue and saturation. Needless to say it is very time consuming, and probably unnecessarily precise for most occupations.
John Burgess
Last edited by interestedparty; 7th November 2002 at 14:58.