Some measurements mean more than others

At the height of the airliner hijackings of the early 1970s, I worked as a designer at a corporate R&D center. One morning, I found a note on my desk asking me to report to the cafeteria. There sat a pair of tall white panels spaced a yard apart. A bundle of cables snaked from the panels to a stack of test instruments. A dozen of my co-workers stood in line near the panels. Each held a handgun.

My boss waved me over. "You're our tallest 'hijacker'. Grab a gun and fall in." He gestured toward a table covered with tagged weapons ranging from cheap "Saturday Night Specials" to sinister-looking black automatics.

A division of our company needed technical assistance with a concealed-weapons detector, my boss explained. "Each panel includes air-core inductors that produce an AC magnetic field. When someone places a metallic object between the coils, the fields' amplitude and phase relationships change. If we can correlate the weapons and their error voltages, we can improve sensitivity and lower the false-alarm rate."

I selected a stainless steel revolver, verified that it wasn't loaded, and joined the line. One of the instrumentation technicians called to me, "Brad, how tall are you, and which weapon do you have?"

"Six feet, five," I said, "and number 37."

"Okay," he replied. "Tuck the gun into your belt above the buckle and walk through slowly." I did so and stood aside to watch my co-workers pass between the coils. We repeated the process, holding our handguns in other positions and, eventually, trading weapons to conduct yet more tests.

A few months later, I stood in line at Philadelphia's airport waiting my turn to pass through the boarding gate's concealed-weapons detector. My briefcase contained a steel can and a steel box filled with electronics. I hand-carried a one-inch diameter, stainless-steel shaft wrapped in paper and a cardboard box holding a pie in an aluminum pan.

Following a security guard's instructions, I walked slowly through the detector. Its alarm remained silent, and the guard waved me through. I could have been carrying a hand grenade, a bomb, a rifle barrel, and a biological weapon. Glancing backward, I noted a competitor's logo emblazoned on the detector.

Thirty years later, concealed-weapons detectors offer improved reliability and enhanced security for passengers and air crew. But even in the aftermath of September 11, I've read reports of airports that under use or ignore weapons detectors, baggage x-ray scanners, and explosive detectors. Fancy security hardware doesn't amount to a damn if no one pays attention to its measurements—or if it's not switched on.