Red tie is a power tie! Comes from the classic navy blue suit/red tie/ white shirt "airline interview" model from back in the day (1960's)... The red tie means power and thats what you want to convey as a pilot applicant. All interviewers will say something to the effect of "we are not hiring FO's, we are hiring CA's". Thats at least how it has been conveyed to me by older airline pilots. FWIW the red tie/black suit/white shirt always looks sharp.