Delta Air Lines has issued a stern reminder to potential flight attendants: wear underwear. A recent two-page memo has outlined strict appearance requirements for interviews, training, and career advancement for present and potential flight attendants.

The guidelines cover grooming, hair, jewellery, and clothing, with a notable emphasis on undergarments. According to the memo, "proper undergarments" are mandatory, but they must remain invisible. The airline also stressed professionalism and neat appearance and ordered current and aspiring flight attendants to adhere to these standards.

"'Delta Flight Attendants spend the most time with our customers and are the face of our airline. They must be passionate about enhancing each customer's experience while embodying the Delta brand. A Delta Flight Attendant is expected to deliver a Welcoming, Elevated and Caring experience while creating moments that matter to our customers. The customer service experience begins the moment a Flight Attendant puts on their uniform. The Delta uniform represents always putting safety first, pride in the Delta culture and demonstrates a genuine graciousness that will be remembered by our customers," the memo read.

To maintain a professional image, Delta outlined specific guidelines:

1. Hair must be naturally coloured, without bold highlights or artificial shades.

2. For longer hair, it must be pulled back and secured above the shoulders. If it extends past the mid-back, it needs to be pinned up.

3. Eyelashes should look natural

4. When it comes to nails, they must be simple and subtle - no neon colours, multi-colour, glitter, or hand-painted designs are allowed

5. Tattoos must be covered, but bandages aren't an acceptable solution

6. Only a single nose piercing is permitted, and the allowed studs include gold, silver, white pearl, or clear diamond/diamond-like.

7. In terms of other piercings, only two earrings per ear are allowed, and they must be smaller than a dime and not hoops.

8. Body piercings, other than the nose, are not allowed to be visible.

When it comes to clothing, Delta emphasised professionalism and fit. The memo mandated that dresses and skirts should fall at or below knee length, and athletic shoes will not permitted. Instead, flight attendants need to opt for closed-toe flats, heels, or sling-back shoes. For those wearing the male uniform, a tie is required with button-collared dress shirts.

During the interview day, Delta said that the airline maintains a strict no-tolerance policy for profanity, chewing gum, and phone or earbud use.

"We will work with you to accommodate a specific manner of dress or physical appearance in keeping with religious beliefs or practices unless it causes a safety hazard or other undue burden on the company," the memo concluded.