Increasingly, passengers' fingerprints and faces are replacing boarding passes.

Delta Air Lines is using the former in an attempt to whisk passengers through a checkpoint for its 50 domestic Delta Sky Clubs, it said Monday.

The airline is working with Clear, a biometric technology company in which it has a minority stake, to implement the service following a pilot program.

The program is free for Delta Sky Club members who are U.S. citizens or permanent residents and it is optional. Travelers using the lounge generally have to show a boarding pass or membership card.

Current members of Clear, a biometric security platform that scans travelers' fingerprints and gives users dedicated security lane for $179 a year, can use their fingerprints on file to get into lounges immediately. Travelers without Clear can enroll in what the airline is calling Delta Biometrics, providing fingerprints that will be used to identify them at Sky Clubs.



Delta is one of several airlines that has been experimenting with passengers "eyes, fingerprints, or faces in an effort to check their identities" and reservations faster. Delta, JetBlue and Lufthansa are working with Customs and Border Protection on biometric exit programs that transmit the data of who is leaving the country and use travelers' features in an effort to board airplanes faster than if boarding passes were scanned.



Lufthansa is experimenting with the procedure at Los Angeles International Airport and said it was able to board an Airbus A380, the largest passenger plane in the world, in 20 minutes.

Clear's co-founder Ken Cornick said he envisions "curb-to-gate" uses for biometrics.

"The beautiful thing about this, your boarding pass is embedded in your identity," he said.

The lounge access isn't Delta's first brush with biometrics. The airline has been experimenting with biometric boarding and baggage drop.

Gil West, Delta's COO, told CNBC the airline is looking for other technologies to make other elements of travel faster. That could include the use of chat bots and voice-recognition technology, he said.