Hi!
It IS a good question, as many airlines are particular.
I know one major airline, where if you don't show up in a dark, conservative suit, with a RED tie and BLACK shoes, they won't hire you.
I know a freight airline, where if you show up in a suit and/or tie, they will NOT hire you. You need to be wearing khaki pants and a polo shirt (casual with a collar).
cliff
KYIP