The Privacy and Civil Liberties Oversight Board, which grew out of a recommendation from the 9/11 Commission, initiated a deep-dive project on facial recognition in aviation security earlier this year, when insiders recognized how TSA and Customs and Border Protection were ramping up the introduction of biometric and facial recognition technology at various points throughout passengers' airport experiences. On top of the pilot at McCarran, the board is also looking into other facial recognition deployments across TSA and CBP, including the biometric entry and exit programs running at various airports for international departures.

Every project the agency is looking into is part of the Homeland Security Department's effort to eventually use biometrics to verify nearly all departing commercial air travelers over the course of the next few years.

"Each deployment raises different issues, different operational considerations, different potential privacy concerns," Adam Klein, the board's chairman, told Nextgov. "It's hard to tell at this point what is the most consequential aspect of this, because these technologies are so new and because the agencies are feeling their ways through this as well."