Bomb-Detection Devices Debated

AMID controversy, US airlines are beginning to install bomb-detection devices ordered by the Federal Aviation Administration. The FAA order is in response to a congressional mandate following last December's bombing of Pan American Flight 103 over Scotland. While the machines, which were developed before the crash, are capable of detecting most bombs, they may not be able to detect smaller ones such as the one-pound bomb believed to have downed the Pan Am plane.

The first machine is already scrutinizing checked baggage at the TWA terminal at New York's Kennedy International Airport and will be publicly unveiled at a press conference today. Many more are on order.

But there is considerable concern that if too much money is invested in the $1 million machines now, airlines will be reluctant to buy better technology when it becomes available within several years. ``It will take another disaster for them to upgrade,'' says Lee Grodzins, the FAA's chief outside consultant on the issue. ``It could get very political very fast.

``We have not made enough tests, which we should do before we put in hundreds of these in airports - before we spend millions,'' Mr. Grodzins says. The FAA plans to require airlines at 40 airports around the world handling US flights to install the machines; it has agreed to pay only for the first few installed. Construction costs are associated with housing the machines, which have massive shielding to protect bystanders from radioactivity, and require nearly 400 square feet of reinforced floor space.

Rep. Cardiss Collins (D) of Illinois, chairwoman of the House Government Activities and Transportation Subcommittee, says ``the FAA's ... rule appears to be based more upon its rush to assure Congress and the public that it has responded to the Pan Am disaster than on a well thought-out approach to explosives detection.''

On Monday, Representative Collins summarized a new General Accounting Office report on the FAA's rules: ``Overall, [the] GAO found that despite additional security measures imposed following Pan Am 103, FAA cannot assure itself that required security procedures are being properly carried out by the airlines at designated high-risk airports.''

By bombarding luggage with neutrons, the new bomb-detection units, known as thermal neutron analyzers - detect nitrogen - an ingredient in explosives, including the plastic explosives that other technologies cannot sniff out. In tests conducted thus far, the machines have detected 95 percent of simulated explosives. Their primary weakness is in identifying small amounts of plastic explosive, a pliable compound which can be rolled like dough, down to one-eighth of an inch.

To locate such small amounts of nitrogen, the machine must be set to a high level of sensitivity. This triggers frequent false alarms, since the machines can be set off by wool sweaters, leather goods, and other objects that contain nitrogen. Critics say this could throw airports into chaos, since detailed alarm-response plans have yet to be worked out.

The FAA has decided that a 5 percent false alarm rate is acceptable. But at that sensitivity rate, it would not have detected the Pan Am bomb. Grodzins says a 10 to 15 percent false-alarm rate would need to be tolerated to detect so small a bomb. That means 30 to 50 bags from a typical, fully loaded wide-body jet would require detailed inspection. ``Passengers are going to have to check in real early,'' says Art Kosatkas, of the Airport Operators Council International.

To combat long waits, Mr. Kosatkas urges use of a variety of pre-screening measures already in use at many foreign airlines.

El Al, the Israeli airline, is considered expert at this. It employs elaborate psychological methods including preflight passenger interviews. Kosatkas says using computer profiles of frequent fliers, families, elderly passengers, and other low-risk groups could reduce the need for bag screening to as little as 3 percent.

``Everyone would like to say there's a system that is secure against terrorists,'' he says. ``But there aren't any free lunches here. Right now, the places that are most secure are those that require every bag to be examined, every person searched and talked to.''

Meanwhile, other technologies which are more sensitive to smaller quantities of nitrogen are being prepared. Prototypes could be available within one to two years. One of the new devices emits no radioactivity, making it more attractive to countries that impose limitations on nuclear technologies.