Colour vision assessment for maritime navigation lookout

A report on the research to find a replacement for the Holmes Wright B (HWB) lantern test carried out on behalf of the MCA.


Colour vision assessment for maritime navigation lookout report

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Seafarers must have their colour vision tested so that we can be sure that they can carry out their work safely. The MCA follows international conventions and uses the Ishihara test for the first screen.

The MCA commissioned research see above and has now moved to the Colour Assessment and Diagnosis (CAD) test (Deck personnel) which measures the severity and type of colour vision loss, and reliably detects congenital deficiency.

The CAD test was developed by City University in conjunction with the UK’s Civil Aviation Authority (CAA) and is being used by the aviation industry worldwide.

Any comments on the report or CAD testing, please email

See MIN 564 and MSN 1839 corrigendum for details of the CAD test and how to arrange a test.

Published 3 June 2016
Last updated 3 June 2016 + show all updates
  1. tagged to working at sea
  2. First published.