Down to the wire

As today's military and commercial aircraft age past their teen years, the many kilometers of wiring buried deep within their structures begin to crack and fray. Once thought to be rare and benign, such faults are found by the hundreds in a typical aircraft. Unlike obvious cracks in a wing or an engine, though, damaged wire is extremely difficult to detect. But the resulting arcing and electromagnetic emissions can be just as deadly: faulty wiring has been blamed for the downing of Swissair 111 near Nova Scotia in 1998 and of TWA 800 off New York's Long Island in 1996. Indeed, any densely wired system is vulnerable-the space shuttle, nuclear power plants, subways and railroads, even the family car.