Watch that twitch – How airport security identifies suspicious characters

When in August last year Britain’s security services uncovered an alleged plot to smuggle the liquid components of a bomb onto an aircraft at Heathrow, the world’s busiest international airport almost ground to a halt as additional passenger checks were ordered. Flights from Heathrow were delayed or cancelled, and many incoming flights were also affected. There seemed to be total confusion. Could mothers take baby milk on board? Should medicines be put into checked baggage? Had duty-free been banned? And what about people arriving on connecting services from airports where no such checks were being carried out? Rules appear to change by the hour. “That sort of confusion can cause passengers not to want to fly with us any more,” says Georgina Graham, IATA’s head of security. She thinks rules still vary in different parts of the world, leaving passengers puzzled. Intelligence to prevent attacks is part of what experts call a “layered” security approach. Other layers include checking identities, scanning people and their luggage and searching them at random. Another and increasingly important one is to see how they behave. “There are identifiers of people who have hostile intent that you can pick up,” says Kip Hawley, the head of American’s Transportation Security Administration. Security officials with the Israel airline El Al spend a long time questioning passengers in order to identify behavioral traits that mark them out as dangerous. But El Al is small and America’s airports would grind to a halt if such time-consuming procedures were adopted everywhere. So the system that will emerge in America is likely to involve pre-screening of passengers right from the time they make their reservation. Mr. Hawley thinks the analysis and interpretation of passengers’ behaviour will be aided by machines. Machines used to scan luggage at airports are getting more powerful too. Instead of just alerting staff to suspicious images, newer scanners will be able to work out what they show. New biometric passports, which contain details such as finger prints and iris scans, will also improve identification. Mr. Hawley insists that security measures should not rely solely on machines, however sophisticated, because threats change. It will take a combination of science and technology, he reckons, to reduce the hassle involved in passing through airports.

The Economist – June 16, 2007

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