PHILADELPHIA (AP) — Philadelphia International Airport will soon begin testing biometric screening on some international flights.

Three different facial recognition systems will be set up at gates that serve outbound flights for American Airlines, British Airways, Lufthansa and Qatar Airways beginning Tuesday, the airport said.

The screening process involves a facial scan, crosschecked with photos already on file with the Customs Border Protection’s traveler verification system.

Passengers can opt out of the screening by contacting an airline or CBP representative.

During the 45-day pilot program, officials will assess each system.

Philadelphia International will be one of 27 airports in the U.S. using the technology.