As stated there are varying degrees of colour blindness.
Logistics officers have the lowest accepted colour perception standard, CP4.
Colour Perception (CP)
There are four standards of colour perception graded as follows:
Standard Test Specification
The correct recognition of coloured lights shown through the paired apertures on the Holmes-Wright lantern at LOW BRIGHTNESS at 6 metres (20 feet) distance in complete darkness
The correct recognition of 13 out of the first 15 plates of the Ishihara Test (24-Plate abridged Edition 1969) shown in random sequence at a distance of 75 cm under standard fluorescent lighting supplied by an artificial daylight fluorescent lamp (British Standard 950: 1967)
The correct recognition of coloured lights shown through the paired apertures on the Holmes-Wright lantern at HIGH BRIGHTNESS at 6 metres (20 feet) distance in complete darkness
The correct recognition of colours used in relevant trade situations, and assessed by simple tests with coloured wires, resistors,
stationery tabs etc.
Personnel who fail to reach the minimum standard of colour perception are to be graded CP5 - failed trade test and colour
Methods of testing colour perception â€“
1. Ishihara plates are used as a screening for all entries.
2. Candidates who pass the Ishihara test are graded CP2 and require no further testing except for those whose critical visual task requires a categorisation of CP1.
3.Candidates who fail the Ishihara test are further tested for CP3 or CP4 according to requirement.