If you are colour blind, you may only fly during the day. For most private pilots this is not a problem, but in commercial aviation it is. Here's the thing.
What is the problem?
When flying at night, colours are more important than during the day. For example, aircraft have navigation lights at the tips of the wing that are either red or green. Red on the left side of the plane, as seen from the cockpit. Green on the right-hand side. When you meet another plane in the sky, you can tell from these colours which side of the plane you are facing.
Airport control towers also have red and green lights to give directions in case the radio equipment fails. Then it is important that you can see the difference between red and green.
One of the ways to see if you can distinguish colours well enough is the Ishara test. This is done during your flight medical examination. Someone who is not colour blind will see a 74 in the image. If you are colour blind you will see a 21:
Colour blind, now what?
If you don't pass the test, the flight medical doctor will do more tests with you. If it turns out that you are colour blind, you can only fly during the day.
Most PPL/LAPL pilots only fly during the day, so this should not be a problem for you. However, if you want to fly scheduled flights, you will have to be able to fly at night and this is a problem.
Can I fly without a licence?
Yes, you can. Even if you are colour blind you can just take a flying lesson. You fly with an instructor as captain. In that case only your instructor has to meet the medical requirements.More information