What would be a "p" on a colour blindness test?

would it be about 50%+ or 100%. I'm talking about an aviation colour blindness test that would allow me to have an unrestricted license. I struggle to see shades of brown (such as beige) but am fine with seperate colours (red, blue, yellow, green etc). However most colour blindness test have a lot of brown in them ;( I usually get 3/6 in tests BTW.