This is just a question I've been wondering about lately. How much does color deficiency affect someone pursuing a career in commercial aviation? Does it depend on position (1st Officer, Capt, etc) or aircraft (B1900 vs. 747) at all?

Hi, bluesky.For the type of flying you are enquiring about, it may, or may not be totally disqualifying, see sentence below.The key words here are

It is a fact that some people who test as red-green blind, but who can pass a light gun test, can also learn to "read" the Isihara color plates almost as well as people with normal color vision.The bad news is that the learning fades over a few days or weeks. The good news is that FAA-approved flight medical exams last minutes to hours.Been there, done that.Of course to make this happen you need access to a set of Isihara plates, and they are incredibly expensive, or at least they were forty years ago. I had an "in" at the NYU Psychology Department and they were happy to host the experiment, so I was able to use their set.

These are the plates they use in the testshttp://colorvisiontesting.com/ishihara.htmjust do the practice tests don't buy them. If you can't pass that test then you will want to have the doctor help you get in contact with the Flight Standards District Office if you are in the United States. If you pass the light gun test then you get a letter that explains that you are color deficient but you are safe to fly at night.If you can't pass the light gun test then you will get a restriction on your medical that say something to the effect that you can't fly at night and are unable to use light gun signal controls from the tower.