Unreliable Secondary Color Vision Tests for Pilot Candidates

If you want to acquire a pilots license, you need to pass medical checkup including a color vision test. If you fail the color blindness test you will get a second chance with a different color vision deficiency check. Unfortunately some researches from the United Kingdom could show, that those secondary color blindness tests are not reliable enough.

Joint Aviation Authorities
Joint Aviation Authorities

The Joint Aviation Authority (JAA) in Europe is the counterpart to the Federal Aviation Administration (FAA) of the United States. The JAA provides the standards of safety in aviation, including the rules on color vision tests for pilot candidates.

For the first color vision screening a set of 24 Ishihara plates are used. If you can identify the first 15 plates correctly without any hesitation you will pass the test. If not, you will get a second chance to find out if your color vision abilities are good enough.

The second test differs between countries. There are four different secondary color blindness tests approved by the JAA and in use:

  1. Nagel Anomaloscope
  2. Holmes-Wright Type A lantern
  3. Spectrolux lantern
  4. Beyne lantern

The anomaloscope is based on matching yellow to a mixture of red and green whereas you can adjust the brightness of yellow and the red-green mixture. The lanterns on the other side consist of several colored lights which have to be identified correctly. They are simulating signal lights used in aviation.

If you pass the second color blindness test you fulfill the color vision requirements for pilot candidates. Therefore one should think that those four tests are leading to the same result. But they are not.

A team around Prof. J. L. Barbur of the Applied Vision Research Center, City University, London, researched those different color vision deficiency tests (Color Vision Tests for Aviation: Comparison of the Anomaloscope and Three Lantern Types).

Secondary Color Blindness Test Results for Deuteranomalous Trichromats
Secondary Color Blindness Test Results
for Deuteranomalous Trichromats

As the results on the right hand side show, it depends on the color blindness test used in your country if you will pass or fail the test. The table shows pass/fail rates on all four secondary color vision tests for people suffering from the most common type of color blindness—deuteranomaly.

The researchers could also show, that all participants with a severe color vision deficiency will fail the tests. So the problem resides only for people with some mild form of color blindness.

Consistency is lacking in color vision testing and an aspiring professional pilot may be accepted without limitation in one country, and rejected outright in another. The different tests also reveal different aspects of color deficiency and the severity of outcome may or may not relate directly to the subject’s ability to discriminate colors.

As a conclusion it can be said that a more reliable and less variable internationally accepted color blindness test has to be found.

16 responses on “Unreliable Secondary Color Vision Tests for Pilot Candidates

  1. Trevor

    Im trevor johnson im 15 years and slightly color blind I am wondering what are the requirements for being color blind ??? I want to be a commercial pilot but am wondering if i can become one with my delema ??

  2. Daniel Flueck Post author

    Trevor, thanks for asking. A lot of colorblind guys ask themselves, if they ever can become pilot.

    Best would be if you would read the article about police officers (it’s about the same as for pilots). It is about the same situation for pilots and police officers. Unfortunately I’ve to tell you that most often they won’t accept you if you have any type of color blindness. But as always, there is a chance and you should wait for your one.

  3. david elliott

    I think its bullshit this colur blind test.I just today came back from my test to get a job with C.P rail. And of course they have a colorblind test and i failed this would have been my dream job for the rest of my working career.Bitter yes because there,s not much i can do to fix the problem plus the police force is out as well the navey and airforce plus who knows what else is out. Guess i get to stay in a shitty factory job for the rest of my working career.

  4. James Nix

    Hey Daniel,

    I’m colourblind. I’m 15 and was looking for a career as an R.A.F Pilot. I was wondering whether there was any “easier way” to put the different types of colourblindness. I’m fairly intelligent but I just Don’t understand the different types of colour blindness, what they mean and what colours they are affected with. This information could potentially tell me whether I could persue a career in the R.A.F as a pilot or to look elsewhere.

    Thanks In Advance,

    James :D

  5. mibo

    Ishihara is well-suited only for screening. Lots of normal trichomats fail it, esp. if plates or illumination are less than perfect (often the case!).

    For pilots it is currently sufficient to pass EITHER the Anomaloscope OR one of the lantern tests (see JAR-FCL 3.225).
    There is little evidence that stronger requirements would improve safety in practice. However, military as well as some airlines may impose higher standards.

    On the various testing methods and their pros and cons, UK CAA and City University have published some excellent work (see http://www.caa.co.uk).

    NB: When viewed on a standard RGB display, the website’s anomaloscope may give you less false matches than the real test. This is because your display cannot show spectral yellow, but has to mix it from red and green as well. If you are a deutan or protan (like myself), your results on a real annomaloscope will most probably be somewhat worse.

  6. utkarsh


    i am 23 years old slightly colour blind. can anyone tell me the procedure for obtaining driver licence in US. i hv heard that one has to pass the colour blindness test. as i canm easily identify the signals on road so i dont think there should be a problem but if they put ishiara before me then its a problem.

  7. Brett Mather

    So I’ll start my story about 3 years ago when I began applying to become an Air Force Pilot through OTS. I was in my senior year at Virginia Tech working on my degree in Aerospace Engineering. After turning in my application to OTS I had to wait a while for the boards to make their decision, so I asked to have my flight physical done so that I would know if I was medically qualified before I even entered the Air Force. With the exception of distant visual acuity everything went well and I was given a waiver for my vision (20/200 uncorrected). I passed the PIP1 color vision test with 13/14 each eye. Unfortunately I ended up not being accepted to OTS and was quite disappointed.

    Searching for what’s next, I found the possibility of a 2-year AFROTC program I could do while working on my Masters degree. I looked at school and was accepted to Embry-Riddle Aeronautical University’s Aerospace Engineering Master’s program and the AFROTC program their. During my first year their I was selected for a Pilot slot before even going to field training.

    I went on to complete my work at Embry-Riddle and commission 3-MAY-09. I had to sit around all summer waiting to EAD but finally did on 3-SEP-09 and began to long drive to Laughlin AFB to wait for ASBC at the end of October, IFS, and someday UPT. I’ve been at Laughlin for just over a month now and received orders to go to Brooks AFB last Wednesday for MFS (Medical Flight Screening). At MFS they did a a few tests, but the only thing I was a bit worried about was my distant vision waiver. All of my tests went fine except for color vision. I scored 10/14 for the PIP1 for each eye failed a few other tests. They kept me for additional color vision tests and determined that I have hereditary red-green (deuteranomalous) green-weak, color deficiency. This is completely disqualifying for Pilot, Navigator, ABM (not sure about this one), Combat Control, Combat Rescue, Special Tactics Officer, OSI, Test Pilot School as an Engineer, and 99% of Astronaut positions.

    This has been quite devastating since all of those jobs I listed have been my dreams and backup plans in case my dreams didn’t work out. Having them all stripped away in one day has motivated me to fight this to the end. I’ve been researching quite a bit to come up with anything I can do. I don’t really know who to contact but I’m planning to start with my commander. I plan to tell my whole story and explain why I believe I am fit for at least one of those jobs.

    I’ve gone my entire life (24 years) without knowing I had any form of color deficiency and have accomplished a lot; I just don’t see how it can be so bad that I would be at a disadvantage now. I’ve read about potential advantages that red-green colorblind people have such as better night vision (which I found one paper going against this), being able to see “faster” (I haven’t found any scientific evidence), and most notably being able to see through and detect camouflaged objects more easily (still don’t have a solid source, just mentioned in other sources).

    From what I can tell the only way I might be able to get around this is to get my commander or someone above him to write an “exception to policy” that would basically say that they are willing to take a risk on me since I might be able to make up for a deficiency with other aptitudes. Other than that, political figures may be able to use their pull somewhat to get me around this (but I know none personally).

    If anyone has any information that may be useful to my cause please contact me at bmather9@gmail.com. Otherwise I’ll be busy looking for other careers (which don’t require perfect color vision) that will be as exciting, dangerous, noble, and challenging (both mentally and physically) as that of an Air Force Pilot.

  8. Mansor

    Hi !
    can you help me that how to pass from color blinde test . cause i am going for a pilot medical test . i am color blinde green and red . i don’t know what should i do , can i find any contact lens can help me recognize the Ishihara test plates . pls pls pls let me know where can i find the contact lenses , wana buy . please give me the address . thanks alot …….

  9. mibo

    Dear Mansor,
    lenses or glasses are not admitted for correcting color vision deficiencies because they won’t really correct it.
    Some of them may improve your abilities in one area at the price of worsening it in others.

    Your country might allow alternative testing methods if you fail the plates
    (anomaloscope or lantern test); please read my comment #7 of July 11, 2009.

    Be aware, however, those can take you to the license at best – but not further. Getting a job is a different issue. Employers (military or civil) often impose higher standards on the required color vision.

  10. erdem

    In the article Unreliable Secondary Color Vision Tests for Pilot Candidates, it says “For the first color vision screening a set of 24 Ishihara plates are used. If you can identify the first 15 plates correctly without any hesitation you will pass the test.”

    but it can be seen that some amount of errors are acceptible according to link below:


    ishihara pseudoisochromatic plates: Concise 14-plate edition: six or more errors on plates 1-11; the 24-plate edition: seven or more errors on plates 1-15; the 38-plate edition: nine or more errors on plates 1-21.

    which one is correct? is it acceptible to make some amount of error?

  11. Daniel Flück Post author

    Erdem, the link you are pointing to is the most recent resource on this topic, at least as far as I know. Therefore you can believe what they are writing. Some errors are ok, but be prepared that your eye specialist will discuss it, if you don’t see them all.

  12. erdem

    thank you Daniel for yor comment. if i cant see them all, of course it is impossible to be a pilot ;)

    but i think some flexibility must be needed for this tests. a few errors can be done.

    i cant open the jar website. do you know requirements of jar related to ishihara test?

  13. Brett Mather

    I have been diagnosed with mild deuteranomaly and have been disqualified from USAF pilot training. I am currently working to get an exception to policy that would allow me to still go to pilot training, and I know how difficult this will be. But I need help with research for my exception to policy package. Today I came up with a simple but interesting idea and tried researching but was unable to find the information I need.

    The idea is that since I have mild deuteranomaly, my M (green) cones are shifted a few nanometers towards the L (red) cones. I also know that many other factors can affect the color perception of people with normal color vision, such as the position of the sun in the sky, weather, hazy, cloudy, etc… So what I’m looking for is a measure of how much the position of the sun would affect the color of an object. I’d bet the bank on the sun shifting light wavelength more than my condition.

    I’ve looked into color temperature a bit and found at dusk or dawn sunlight has a color temp of approx. 3200 K and at noon its around 6500 K. My problem is I’ve been unable to relate this change of 3200 K to 6500 K to a change in wavelength (nanometers).

    Any information on how much the sun would affect color perception, or how many nanometers a person with mild deuteranomaly would be shifted would be greatly appreciated.

    I can be contacted at: bmather9@gmail.com