Airline employees are already doing much more than you think.

According to the International Labor Organization, an estimated 21 million people around the globe are trapped in some form of forced labor — and airlines, hotels and other travel companies are playing a role in these people’s lives, for better or for worse.

Now, American Airlines is the latest company to step up and take part in efforts to help victims of human trafficking and child sexual exploitation.

American Airlines recently started working with the nonprofit ECPAT-USA (End Child Prostitution and Trafficking) to enforce corporate policies, train its 120,000 employees, and to provide information to travelers on the issues of human trafficking. Delta Airlines and Volaris also have similar agreements with ECPAT-USA.

“People think this is only happening in other countries. They don't realize it could be happening on a domestic carrier on a domestic flight,” Michelle Guelbart, director of private sector engagement at ECPAT-USA, told Dallas News.

Guelbart asserts that airline employees play a big role in identifying trafficking victims. Often times, a victim is moved across a border or across a large distance on an airplane, a bus, or a train.

Warning signs flight attendants can watch out for, according to Guelbart include: if a person of interest isn't in control of their own documentation or money, if the individual is being kept away from security, or if they are not allowed to speak for themselves. Any of these could trigger a response.

On a short flight from Seattle to San Francisco in 2011, for example, Alaska Airlines flight attendant Sheila Frederick saved a teenage trafficking victim by leaving her a note in the bathroom.