There is an additional aspect to successfully doing your job as a TSA officer: the ability to distinguish colors. To this end, the organization includes the Farnsworth D-15 Color Vision Test in the Airport Assessment, which is three minute-pass/fail affair.
So, how does this test work?
Simply, you will be provided with 15 small cubes, each with varying shades of any given color. According to hue, it is your job to line up all the colors in the right order. If you have too many mistakes in sorting the colors, you fail. While you are granted a second chance to pass, a second failure will result in automatic disqualification from the test.
After a second failure, you will not be allowed to take the Airport Assessment for six whole months.