Delta says that clothing “must be professional and fit properly” — “dresses and skirts should be at or below knee length.” Athletic shoes are not allowed, and shoes worn must be closed-toe flats, heels or slingback. For those who wear the male uniform, a tie is required with button-collared dress shirts.

Delta Air Lines has issued a gentle reminder to flight attendant hopefuls about its “appearance requirements” for employees — more specifically, that underwear is required.