Answers to your questions about colour vision and the regulation for aircrew
What is CVD ( Colour Vision Deficiency) ?
From Jordan Penning "The UK CAA Colour Vision Regulation – Truly A Grey Area!" 8-12 % of the world population, mostly males have a level of colour deficiency with women only 0.5%. (Nei.nih.gov, 2019) (Nhs. uk, 2020) 93% of pilots are males according to (Aopa.org, 2019). CVD regulation, therefore, affects a considerable number of candidates. There is increasing evidence that colour vision is not necessary at all within aviation, there is also huge ambiguity and misconception about what type of regulation needs to be implemented. (Cvdpa.com, 2020) (CVDPA, 2010) The problem is that colour vision is an extensive and relatively unknown subject where a lot of myths that derive from old train and marine regulation have been implemented in today’s aviation regulation as this existed before flight and have had very little change. (Defence Technology Agency, 2015) ICAO quotes that ‘the problem with colour vision standards for pilots and air traffic controllers is that there is very little information which shows the real, practical implications of colour vision defects on aviation safety’. (Manual of Civil Aviation Medicine, 2012) Colour vision can be classified by severity and type, there are 3 types of CVD.
Deutan-A form of Red -Green Colour deficiency where Green is less sensitive
Protan- A form of Red -Green Colour deficiency where Red is less sensitive
Tritan-Yellow /blue colour deficiency
There are 3 different severity levels, mild , moderate and severe.
Mild to moderate candidates tend to be known a Trichromats which means they have 3 cones like normal colour vision individuals have however one cone specific to the type of deficiency has its wavelength shifted, the severity is determined by the amount it shifted.
Severe candidates tend to be known as Drichromats , someone who has only 2 of the 3 cones.
Has there been any accident related to CVD ?
There have never been any reported aviation accidents attributed to colour vision. (CVDPA, 2017) Therefore the common question is whether colour vision regulation is actually required for commercial aviation. Some authorities, however, quote that the FedEx 1478 crash was due to a colour vision defective pilot. The aircraft crashed into a forest about a mile short of the Runway 9 threshold. The Precision Approach Path Indicator (PAPI) device servicing the runway was supposedly displaying four red lights on final approach, meaning the aircraft was too low for landing. In the paper linked below by CVDPA, they argue that the crash of FedEx Flight 1478 raises the more fundamental question of whether colour-coded information should be used at all in aviation. While the First Officer, piloting, had defective colour vision, the Captain and the Flight Engineer, both actively involved in the approach , had normal colour vision, yet did not see, and did not use, the colour-coded information from the PAPI device. All three crew had equal participation and awareness within the flight and therefore it is unfair to put the blame on colour vision. The paper attached assess in-depth the possible causes. https://www.cvdpa.com/images/further_reading/articles/Pape%20and%20Crassini%20The%20Puzzle%20JASAM%202013.pdf
Can you be accepted for a Class 1 medical with CVD ?
Absolutely, it depends on how severe your colour deficiency is and what are the regulations within the state that you are applying for your medical. Each state will have their own testing methods. We at ECDAA believe that any individual with CVD can safely fly commercial aircraft as studies have suggested that colour vision is not necessary. Some countries allow pilots with severe CVD to fly commercially, there has never been an accident within the 30+ years that some of these countries have been implementing this ruling and thus proves that colour vision is not necessary to fly a commercial aircraft safely.
Is it possible to be denied a Class 1 in one authority and be accepted in another ?
It is definitely possible to be denied in one authority and accepted in another due to the wide amount of testing options and the lack of standardisation across states. Even within EASA the regulation varies from state to state. For example, UK CAA only accepts the CAD test for initial class 1 medicals however most other EASA states accept also the Lantern and Anomalscope tests. Have a look at what tests are available in the next part below.
What tests are there for CVD?
They are a large variety of tests for CVD. These tests are split into certain categories: Screening, Lab-based and practical assessments. The type of tests available depends on the country in which you seek your medical and the authority's regulation. Screening tests will be used to assess every candidate's colour vision on an initial medical, the most common being the Ishihara test. However, even the pass mark for this test can vary from country to country.If this test is failed then a secondary test needs to be undertaken which is either a Lab-based or practical test. Some countries offer both types of testing.
For a great chart of the tests available in each authority have a look at our blog post about the testing options, please click here
How many tests can you do?
There is no limit to the number of tests that you can do , but it's up to the authority to which tests they will accept. For example within the EASA regulation it lists 3 secondary tests, the regulation states 'pass either by' which means that all three tests can be taken and only 1 has to be passed to be classed as colour safe.
Do you get tested for Colour Vision every medical renewal ?
If you pass via the Ishihara test on the initial medical then a candidate will be tested at every renewal for a medical under the EASA regulation . If the candidate passes via a secondary test then they will not have to redo this test. They will be classed as colour safe as colour vision does not change if you have a deficiency.
What are the CVD requirements for different aircrew roles?
ATC tends to be more strict than pilots
More info coming soon