The pilots of a Boeing 767 jetliner, misled by the complex gauges of their new aircraft, ran out of fuel in midair with 69 passengers aboard.
A convict, under computer-monitored house arrest, slipped his electronic manacles to commit murder because the system monitoring his whereabouts was not designed to redial authorities when it encountered a busy signal.
And in a similar slip of technology, when a tree branch brushed a high-voltage transmission line in Oregon last week, what has been called the largest machine in the world--the West's power grid--stumbled, then failed. The resulting outage in seven states, apparently caused by the simultaneous loss of six separate power lines, triggered a cascade of other problems, ranging from dead stoplights to air traffic control snarls across half the United States.
Such unexpected mishaps are the "revenge effects" of technology, according to Princeton historian Edward Tenner.
Yale sociologist Charles Perrow calls them "normal accidents."
They are the unpredictable but inevitable consequences of the growing complexity of a technological civilization, systems experts say. Even momentary glitches in how things work feed society's traditional uneasiness over the devil's bargain between the benefits and the drawbacks of progress.
More than ever, Americans appear to be worshiping at the altar of high technology, and their belief in its reliability is the secular faith that sustains them. But the infallibility of complex engineering systems is as much an illusion as the feeling of control they confer upon their users.
And when such complex systems fail, it leaves behind a snarl of recriminations. Who is to blame--the public that demands technical infallibility or the engineers who promise it?
The answer may be that human ingenuity is on a collision course with the mathematics of chaos--as technology develops into more complex systems, small problems can combine in ways that designers do not foresee and certainly do not intend. Some experts are not sure whether it is the creators of the systems or society that has gotten ahead of itself.
"Global problems can result from seemingly isolated events," said Peter G. Neumann, an expert on risk and technology at SRI International in Menlo Park.
Each time a single technological failure is fixed, "people keep saying this will never happen again, but it keeps happening again and again," he said. "Whether we like it or not, we must coexist with people and systems of unknown and unidentifiable trustworthiness."
Indeed, the public's faith in a system--whether it is the air traffic control network, the blood supply or electronic banking--may be as important as the integrity of its engineering.
"The confidence is critical to the effective working of a system," said Paul Slovic, a specialist in public perception of risk at Decision Research in Eugene, Ore. "It is a delicate balance. All of these are complicated management systems and we tend to trust them until something happens that shakes our faith."
But as increasingly complex subsystems are linked together--whether they are circuits on a Pentium computer chip or households on a national power grid--there is no way anyone ever can completely understand what has been created and the myriad ways it may fail. It is possible, some say, that many of the systems in which the public places its trust have grown too complicated and expensive to ever be made completely reliable. The best that engineers can do is attempt to design these systems to fail safely, said USC professor Ralph Keeney. The power outage that struck Saturday was a good example of a managed failure that only affected a fraction of the people served by the grid.
But all too often the safety systems themselves are the reasons a problem gets out of control.
In 1990, a minor electronic failure paralyzed AT&T's long distance system for 11 hours. Flaws in the automated recovery system triggered a spasm of repeating failures that quickly spread through the entire network.
That flawed safety net had been designed in response to a major failure a decade earlier of the ARPANET, the computer network that was the predecessor of today's Internet.
The inability, or unwillingness, to fathom the complexity of a system is responsible for the paradoxical effects of many innovations: Better roads cause more traffic congestion, not less. Antibiotics lead to more virulent diseases.
Some years ago, farmers in the Southeast doused their fields with pesticides to control deadly fire ants. They killed all the pest's natural predators instead, leaving the stinging ants more uncontrollable than ever.
Luckily, for many people the weekend outage was no more than a momentary interruption in service. Like the unlucky Air Canada jet that ran out of gas in 1983, the behemoth of a technological society usually is able to glide safely to rest in the aftermath of each serious system failure.
