"Send him home. He is not wearing a blue suit and red conservative power tie! He must not want to work here"
Think about how stupid that sounds. Do you really think anyone has ever had that conversation at any decent place to work?
You obviously weren't around or don't remember the Plato/Dresser days. These guys wouldn't hire you if they didn't like the way you parted your hair, let alone if you didn't wear the right clothes. It may sound ridiculous to you, but clothes matter in an interview. For that matter, clothes just matter in general as to how people percieve you. Your clothes are the way you make a first impression. Best not to screw it up.
Most of this stuff is universal to job interviews in all industries, not just aviation:
1. Suit should be dark navy blue or charcoal gray. Black is considered too "powerful" for general business use and should only be used for special occassions (funerals, weddings, dinner at upscale restaurant, etc...) Brown and light gray are considered too casual for an interview. Use Mens Wearhouse, Jos A. Bank, or Brooks Brothers. Now isn't the time to bring out that fancy Hugo Boss suit that you dropped $1100 on. Dressing better than the guy interviewing you is a big mistake.
2. No pocket squares, cuff links, or visible jewelry. Too fancy for interview attire.
3. Shirt should be either solid white or french blue. Pointed or spread collar and barrel cuffs. If you use starch, use only light starch because heavier starch can actually start to rub off onto your suit after a long day. Not good for a dark suit. I never use starch and I hand-press my shirts. Mens Wearhouse has excellent shirts that are wrinkle and stain resistent.
4. Blue, yellow, or red tie is best with a conservative pattern. Half-windsor knot with a point collar or full-windsor with a spread collar. Make sure it is 100% silk and hand-sewn. The ties in any of the above stores will do.
5. Socks should match your pants, not your shoes. If you're wearing cordovan shoes (burgandy color) and a blue suit, then match the socks to the suit, not the shoes.
6. Shoes and belt should match. Lace-up shoes only. I always use Allan-Edmonds or Johnston & Murphy. If you use a shoe-tree and don't wear them more than a couple of times a week then they'll last for 10 years easily. It used to be that black shoes with a blue suit was frowned upon, but that's changed over the past 10 years or so. You can use either black or cordovan now. I always think that cordovan looks better with blue, though.