I believe the 15th guy is the senior enlisted, and that's why he is standing a bit off from the group. Most of them are officers, plus they are air force so hand placement is going to be where ever they feel like at the moment. the pilots are wearing the jumpsuits, while the others are wearing a standard work uniform. I was looking for someone to mention the shadows. They look off, or unnatural. I ran the pic through photo forensics but I can't detect any fuckery.