Ultimately, the technology could “get rid of the boarding pass completely,” with fliers’ faces serving as their tickets, said Michael Ibbitson, chief information officer of London Gatwick Airport. Gatwick performed a trial this year in which it processed 3,000 British Airways IAG.MC +1.15% fliers without boarding passes. The fliers scanned their irises when checking in, enabling cameras at security checkpoints and boarding gates to automatically recognize them. “We’re only just starting to see what biometrics can do,” he said.

Proponents, including government and industry officials, say that automation of airport security holds the promise to free human screeners so they can focus on detecting suspicious behavior or monitoring flagged travelers. And for some aspects of security, they say, computers can be more thorough and less error-prone than humans.

Critics, however, worry that relying too much on automation will dull the senses of human screeners and remove the human intuition that can detect when something just doesn’t seem right.