Here is an opinion article by Heather Poole that was originally featured on Mashable on January 12th, 2016. There is a wealth of information regarding warning signs of human trafficking.

"A few years ago, on board a flight from Los Angeles to New York, a group of young girls wore nothing but jeans and T-shirts — in the middle of winter. They didn’t speak English, and they didn't speak to each other the entire flight. I remember thinking it was odd, but I didn't know what to do about it.

 My mother, a retired flight attendant, once had a man on board a flight traveling with a teenage girl. They didn’t look like they were related, and they weren’t friendly with each other either.

“When I asked the girl what she’d like to drink, he answered for her," my mother said. "I thought that was weird since they weren’t speaking to each other. If I'd known more about human trafficking, I might have engaged them in conversation to feel the situation out, but at that time we didn't know anything about it."

Back then human trafficking never crossed our minds. But that has changed...

A few years ago, my airline started training us on spotting telltale signs of human trafficking on the plane. Can the passenger speak for themselves, or is someone with them controlling what they say? Does the passenger avoid eye contact? Do they appear fearful, anxious, tense, depressed, nervous, submissive? Are they dressed inappropriately, or do they have few possessions — even on a long flight? Can the passenger move independently, or are they accompanied by someone seemingly controlling their every movement?..."

You can read the rest here.