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Though it takes a sick mind, it isn’t hard to bomb a U.S. airliner. The security equipment in place at the nation’s airports was mandated in the 1970s, when the chief concern was hijackings, not terrorist bombings. So while the metal detectors we all step through can uncover guns, knives, and other metal weapons, they can’t find hidden explosives. Neither can the x-ray machines that scan carry-on bags, as well as checked luggage for international flights. Checked luggage and mail for domestic flights are not examined at all.

But recent bombings in Oklahoma City and Atlanta’s Olympic Park, the FBI’s discovery of plots to blow up U.S. airliners, and speculation about the downing of TWA Flight 800 in July have produced strong calls for protection against demolition-minded terrorists. Politicians have been jolted into action. After years of little legislative attention, Congress on October 9 suddenly appropriated $160 million for the Federal Aviation Administration (FAA) to rush more than 500 bomb detection units of various types into airports for a year of testing.

Some observers say this action is long overdue. Others say it is too hasty. No fewer than 10 detection schemes are vying for position-from x-ray machines and magnetic resonance imagers to chemical-vapor sniffers. Although they have different pros and cons, no single machine is both fast enough and accurate enough to meet the FAA’s certification criteria. All the proposed systems are expensive. They also raise serious social concerns. The National Research Council (NRC) recently concluded that ultimately “limitations on the technology will be imposed as a result of passenger intolerance for invasion of privacy, delays, or discomfort.”

Even if the technical and human issues are resolved, the biggest question remains: Who will pay to protect the skies, and is the price worth paying?

The drive to screen for bombs gained momentum after the 1988 downing of Pan Am Flight 103 over Lockerbie, Scotland, which killed all 259 people on board. R&D accelerated on technology that could detect less than a pound of explosives hidden on a person’s body or in luggage. Legislation directed the FAA to find automated machines that could uncover explosives without human operators.

In 1993 the FAA set two key standards. To become certified, a machine would have to process 450 people or bags an hour, the approximate “throughput” of current carry-on bag scanners. It would also have to have a low false-alarm rate, reportedly 10 to 20 percent of all inspections. Meeting both numbers proved difficult, and the automation requirement was an obstacle that few manufacturers were able to overcome (most of the latest systems still need people to run them). But U.S. manufacturers didn’t seem concerned; they were selling systems to Israel and Europe, where standards are less stringent. Besides, no further bombings had occurred, so U.S. airlines were not buying.

The heat increased in 1995 after Ramzi Ahmed Yousef, the suspected mastermind behind the 1993 World Trade Center bombing, was implicated in a plot to blow up a dozen U.S. airliners. His laptop computer, confiscated in the Philippines, stored flight schedules and detonation times. Accordingly, the NRC formed a committee on detection technologies. It issued its first report, pointing out relative strengths and weaknesses of various systems, in June 1996. The FAA responded by assembling a security task force on the morning of July 17; that evening, TWA Flight 800 blew up over Long Island Sound, killing all 230 people aboard.

Although the cause has yet to be determined, the July catastrophe set off a flurry of activity that is rapidly putting new technology into airports. The White House set up a Commission on Aviation Safety and Security under Vice-President Al Gore and gave it a mere 45 days to present a national technical strategy. In the frantic last days of its fall session, Congress banged out the October 9 Federal Aviation Reauthorization Act. The legislation earmarked $160 million for aviation security, tracking the Gore commission’s recommendations that a variety of new detection techniques be tried out in real settings to identify the ones that are most ready for deployment.

Just like that, the FAA had money and a mandate. It quickly decided to purchase and deploy more than 50 special x-ray units, 400 chemical-sniffing machines, and other instruments to screen passengers and bags at 75 of the country’s largest airports. Tests would be held over the next year. The first contracts were let the week before Thanksgiving. This infusion has rekindled widespread work-and debate.

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