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. It was not just flights starting from
Heathrow that were delayed or cancelled, but many incoming services too. In the
following days British Airways alone cut more than I 200 flights.
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 people behave. "There are identifiers of people who have
hostile intent that you can pick up," says Kip Hawley, the head of America’s
Transportation Security Administration. "Our testing indicates an extraordinary
high degree of success." Security officials with the Israeli
airline El A1 already spend a long time questioning passengers in order to
identify behavioral traits that mark them out as dangerous. But El A1 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. Then, as they go through the different layers of security at the
airport, some passengers will be asked questions by specially trained staff who
are looking out for things like involuntary facial-muscle movements. A twitch
(颤搐) is impossible to hide. "The more you try to avoid it, the more pronounced
it becomes," says Mr. Hawley. Machines used to scan luggage at
airportsare 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 fingerprints and iris(虹膜)
scans, will also improve identification. But Mr. Hawley insists
that security measures should not rely solely on machines however they are
sophisticated, as threats change. It will take a combination of science and
technology to reduce the hassle(麻烦) involved in passing through airports. Why shouldn’t security measures depend entirely on machines