Can the Sun Change Color Perception More Than a Mild Color Vision Deficiency?

Brett wants to become a pilot. But he is suffering from a mild form of color vision deficiency which disqualified him.

He is now looking for any possibility which could show, that in some cases weak colorblind people are not less suitable than people with normal color vision as there are many factors which can have quite an impact on your performance and which you always have to be aware of.

Read his request, you might be able to help him:

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:

After reading his thoughts you maybe realized that your situation is quite similar. Hereafter you can read his whole story which might help us all to find a better solution to the problem, that many colorblind people are rejected from a job just because of some color vision tests, which are most of the time to unspecific and much to restrictive.

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 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.

14 responses on “Can the Sun Change Color Perception More Than a Mild Color Vision Deficiency?

  1. Peter

    Hi Daniel, long time no talk! I am contacting Brett about making these calculations. I think it is a hard sell though, unfortunately.

    Hope you’re well!

  2. Jon

    Sorry Brett but I really think you are wasting you time. You are seriously clutching at straws with the whole colour temperature thing. Have you stopped to think about how many thousands of people are rejected every year for exactly the same reason as you? What makes you think you are special?

    Sorry to sound harsh but I totally understand your pain. I spent my childhood wanting to be an Army helicopter pilot like my father but was rejected for two reasons. Not only do I need correction for distance vision (like you), I am also deuteranomalous. I had a second shock last year when I tried to switch to a new career in yachting and the old deuteranomaly got in the way again.

    Having a very mild CVD like we do is incredibly frustrating because we don’t notice it at all in our daily lives, so we assume there is really nothing wrong with us. (And really, there isn’t -research says that we can see just as many colours as “normal” trichromats, just different ones.)

    To be honest I still sometimes feel a little sad every time I see a helicopter fly over, or look at old pictures of my dad from his flying days. I just try to remind myself how lucky I am to be able to see at all, and be generally healthy. Things could be so much worse!

    I think time spent pursuing this will be time wasted when you could be doing something constructive. Maybe one day a new form of vision test will be introduced (see Daniel’s latest article) but I would imagine this will be many years away. (And there’s no guarantee you would pass.)

    Whatever you choose to do I wish you the best of luck. An intelligent guy like you will acheive a huge amount whatever career you choose.

  3. Brett Mather

    Anyone who’s interested, I just found a new website (

    Evidently this is quite a big problem that many agencies are ignorant towards this.

  4. Jon

    Brett Mather Says:
    March 5th, 2010 at 17:33
    “And really, there isn’t -research says that we can see just as many colours as “normal” trichromats, just different ones”

    You’re wrong (

    How does that make me wrong? That link is actually the piece of research I was referring to, which completely confirms my point.
    The point being that deuteranomalous people can discriminate the same NUMBER of shades as people with normal colour vision, but a different range of shades, some of which can’t be discriminated by a “normal” person. (At least according to this study). I’m not saying the research is 100% correct, I haven’t read the original paper and like all research it could be flawed.

    But you have clearly either misunderstood me or the article if you think it makes me wrong.

    This article refers to the same paper and also gives an interesting description:

    You should be encouraged by this as it suggests that it is actually incorrect to describe deuteranomaly as a “deficiency”. It is more of a “colour vision variation”. (That’s how I like to think of it anyway!) I still don’t believe for one minute that you will ever get the military authorities to change their mind, but it is a good angle to try.

    Also have you tried taking the medical to become a civilian pilot? I believe that in the US, people who can’t pass the Ishihara test can instead get something called a “Statement of Demonstrated Ability” (SODA) where if you are able to prove that you can identify control tower light gun signals you can still get a pass. You may find that you could be eligible to be a (non-military) pilot in this way. Worth a try.

  5. Jon

    Thanks very much for the link to the cvd pilots site. Looks very interesting. I had no idea that the UK Civil Aviation Authority had already adopted the new CAD test. Well worth a look.

  6. Brett Mather


    I sincerely apologize as I completely misunderstood what you meant with what I quoted.

    I get told frequently that I should give up on trying to be a military pilot but as I am already at a pilot training base, ready to go, I feel that I still have a chance and that it’s worth my time to try. I truly believe that what I have is not a “deficiency” as it has never affected me in a negative way and that I am more than capable of becoming a succesful military aviator. I’m not willing to give up at this point and I don’t like being told that I should or that my efforts are pointless.

    That being said, your writing made me slightly angry and in my rage I assumed your quote meant something negative for my case, but I now fully understand it and am glad to know that we agree.

    Please forgive my misunderstanding and let me know if you have any further information that may help me.

    As for the military, I agree, they will probably not change their minds, but in contrast I have information about 75 current aviators with color vision deficiecies. These flyers made it through training undetected and were discovered later, but given waivers to continue flying. Obviously alot of money has been invested in them and that is probably the main reason they are given waivers; nonetheless it is an excellent argument for my case.

    As far as civlian flying goes, I’m a glider pilot (which requires no medical) but I do have a Class I Medical and have no problems passing Ishihara. I know I could fly civilian and probably will, but as I’m sure you know military flying is different and it’s what I want to do.

    I thank you and everyone else for your support.

  7. Jon

    Hi Brett,

    You haven’t posted here for a while, how is your campaign going? Have you made any progress?
    I am pessimistic about your chances of succeeding but I do wish you the very best.
    In my opinion deuteranomalous people are discriminated against unfairly in so many ways. It’s about time it stopped.

  8. Jon


    One more thing – you mention that you “have no problems passing Ishihara”. Are you sure you’ve got this right?

    I was under the impression that the Ishihara test was the “gold standard” (and the “hardest” to pass.)

    For example an applicant to the UK military will be shown Ishihara plates first, and only asked to do a HW lantern test if they can’t identify all the plates. I believe you can still be accepted for most jobs if you pass the lantern test but not the ishihara.

    I was also under the impression that a small proportion of deuteranomalous people can pass a lantern test, but none will pass the Ishihara plates.

    If you passed Ishihara which was the test that caused you to fail?

    Just curious to learn more. If you could correct any mistakes I’ve made in my assumptions I would appreciate it.

  9. Brett Mather

    I’m absolutely certain about the Ishihara, I scored 12/14 on them on my initial flying physical and have taken that test (or a similar variation, either waggoner or Dvorine) at least a dozen times since.

    Ishihara is the most common, but is not the “golden standard” according to most doctors I’ve talked to. An anomaloscope is a much better diagnostic test in determining a deficiency and it is considered the “golden standard” from what I’ve heard.

    Different military services differ in their testing methods. Most in the US (Navy, Marines, and Army) use Ishihara (or similar) first, followed by a FALANT if the first is failed. Unfortunately for me, the USAF initially used 2 PIP tests (PIP I and SPIP II) which I passed. Later I was sent to a screening where I was given additional tests which raised a question about my color vision (SPIP III and F2 plate). After this I was given a cone contrast test, D15 arrangement, and an anomaloscope. The diagnosis was for moderate to severe deuteranomaly, which I believe is blatantly wrong considering I’ve never noticed this before in my life. Further testing from a civilian doctor revealed only mild deuteranomaly. The USAF standard for pilots is “no degree of anomaly” so no matter how many tests I can pass and how good my color vision actually is, I can’t fly.

    It seems to me that it is typically easier for deuteranoms to pass the FALANT than the Ishihara, but I pass both even though there is no question that I am a deuteranom.

    To follow up on my story, my attempt at an exception to policy was denied and the USAF actually sent me to the “Force Shaping” board to see if I should be retained in the military (we are over-manned right now); pretty wild considering all I did was show up for pilot training and get disqualified for color vision.

    Recently the USAF decided to keep me and reclassify me as a flight test engineer (job I worked in previously as a civilian) so I’ll be moving to Edwards AFB, CA in a few weeks. My job supposedly involves flying approx twice a week, but in the backseat for flight test chase planes and such. I’m currently fighting to get a waiver for color vision for this job and have met quite a bit of resistance so far. I think there is much better chance they will allow me to have this job compared to pilot training. It’s hard to believe I was able to perform this job as a civilian without knowing about my condition but now it is all being questioned because of color vision.

    Whether this job works out or not, I’m planning an inter-service transfer into Naval Aviation since I pass both of their color vision tests (FALANT or PIP I). I’ve talked with 2 individuals who succeeded in such transfers from the USAF for color vision deficiency and are currently flying in the Navy. Unfortunately, I don’t meet the uncorrected distance vision standard for the Navy (more strict than USAF), so I’m preparing for PRK eye surgery sometime after moving to California.

    Thanks to everyone for all the help; this has all been tough for me to go through, but I’m on my way out of this mess whether that involves flying or not.

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