Flying abroad? You may have to go through a facial scan at the airport.

If you happen to be traveling out of the country through certain US airports during this holiday season, you may have to go through yet another security check at the airport: a facial scan.

In fact, you may already have already been scanned and didn't even know it. That's what happened to Tanvi Misra before she boarded a flight to India from Washington Dulles International Airport.

“What I thought was actually just a machine that was supposed to scan my boarding pass was actually a facial recognition machine,” Misra said. “And it was quite a surprise that that kind of process had been taking place without much communication about what it was, or what options I had."

Misra is a staff writer at CityLab and wrote about this experience. As it turns out, the facial recognition scanning is part of a US government pilot program at nine airports across the country. 

The official goal of the program seems to be to verify that people are using identification documents that are truly theirs. But it doesn't seem to always work that way.

“The Department of Homeland Security and Customs and Border Protection officials argue that this is going to make the boarding process a lot more efficient. … But what the critics say is there are a lot of issues when it comes to how this thing works. There seemed to be a lot of inaccuracies,” Misra said.

To hear more about the technology and the concerns privacy experts have listen to an interview with Misra by listening to the audio, above.