Routine colour vision testing is carried out when required using the Ishihara test. If the applicant passes, no further testing is required.
If an applicant fails the Ishihara test (please note that the criteria for a pass vary depending on the authority or agency for whom the test is conducted) we have further colour vision testing facilities as follows:
- CAD test. This is a computer-based test acceptable to the UK CAA for EASA Class 1 and 2 certification, and European Class 3 certification for air traffic control officers. We only carry out this test in conjunction with an initial Class 1 or 2 medical, or as required for certificatory purposes by holders of aircrew licences or medical certificates. We do not carry out this test for certification advisory purposes, eg in the case of an individual with concerns about colour vision who wishes to have the test prior to applying for initial CAA Class 1 certification, or in the case of Cabin Crew; in these cases we recommend that such individuals arrange comprehensive colour vision testing by Dr Adrian Chorley of Aviation Vision Services, or at City University, London http://www.city.ac.uk/avot – follow link to “Book an appointment with the AVOT centre”.
- Farnsworth Lantern test. (This is similar to the Holmes-Wright Lantern, which was used by the UK CAA for professional pilots until it was superseded by the CAD test); pairs of coloured lights are displayed, the applicant has to name the colours. It is acceptable to a number of authorities, including the US FAA and Australian CASA.
- Giles-Archer Lantern test: This is a very simple test, one coloured light is displayed at a time, the applicant has to name the colours. It is currently used for airside driving assessment. Prior to 1999 it was used in the UK for private pilots.
- Trafford anomaloscope: This is a modern electronic anomaloscope, working on the principle of the Nagel anomaloscope; the applicant views a left half of a disc which emits light from a yellow monochromatic LED, and a right half of a disc which emits a light comprising a mixture of red and green. He adjusts the red/green mixture and the brightness of the monochromatic yellow until both halves appear to have identical colour and brightness; the range of red/green mixtures which achieve this (the “matching range”) are noted, this gives an indication of the type of colour vision anomaly. It is of scientific and educational interest, however it is not used for certificatory purposes.