The craft of airplane design is one of precision, of computer projections and reassuring statistics. The act of blowing a plane from the sky is a chaos of evil intent, slim opportunity and hellish luck.
This is why, beyond the awful loss of 230 lives, aeronautics and terrorism experts are so disturbed by the explosion of TWA 800.
For them, the mystery of what happened at 13,700 feet stirs special dread: They see either a mechanical failure unlike anything experienced or a terrorist act of accuracy and precision rarely seen.
“If it was an accident, it would scare the hell out of us,” Michael Barr, director of aviation safety programs at the University of Southern California, said Monday. “These planes just don’t blow up. There’s too many fire walls, too many checks and balances.”
Christopher Ronay is equally troubled. As head of the FBI bomb unit for seven years, Ronay investigated 30 aircraft bombings. He retired in 1994.
“I can’t recall anything that has had a catastrophic effect like this case,” he said. “You could blow the hell out of a cargo compartment with a luggage bomb, but you have to blow up a fuel cell or an engine to get an explosion like that.”
Their perplexed fears are based on witness accounts of a huge orange fireball, a possible marker of exploding jet fuel. The Boeing 747 had taken off just 17 minutes before, its tanks fully loaded with 48,445 gallons of fuel for the long flight to France.
The specific fuel involved is called Jet A; it’s a derivative of kerosene and a sluggish explosive. To explode, it must mix with air, an indication one or more of the eight fuel cells in the jumbo jet’s wings were breached - either by violent engine or mechanical failure, by a well-placed bomb or possibly by a missile.
There have been cases of sudden mechanical failure that caused fire and the loss of aircraft. An Air Force C-141 transport plane crashed in Europe in the late 1970s when an engine exploded, spraying hot fragments that ignited paint in a cargo hold.
A Boeing 767 ripped to pieces over Thailand in 1991 when a computer glitch caused one engine to deploy its reverse thruster, sending the plane into a vicious spin.
But in neither case was there a cataclysmic explosion.
Before TWA 800 went down last week, there had never been an explosion of such ferocity aboard a 747-100, a “wet-wing” or plane that carries all its fuel in wing tanks.
“You have to have instant ignition into a large fuel source,” said Barr, who trains accident investigators. “The way those fuel tanks are sealed, it just doesn’t happen.”
Similarly, few bombing attempts on commercial aircraft have ended in such a fiery conclusion. In many cases, jetliners have survived even severe damage from explosions and landed safely.
Until now, the crash of Pan Am 103 at Lockerbie, Scotland, in 1988 was arguably the most memorably horrific aircraft bombing. But there was no fiery explosion - until fuel-laden parts of the plane hit the ground.
A pound of Semtex, a Czech-made plastic explosive, was hidden in a radio-cassette player and, when detonated by a timing device, blew a hole in the forward hull. The blast weakened an adjacent - and crucial - structural support. As the plane flew at 500 mph seven miles up, the cockpit section buckled back toward the fuselage. The horrible physics of those stresses broke the plane into five sections that tumbled to Earth over the Scottish countryside.
“The dumb luck of the tragedy is that the terrorist who places a suitcase in the system doesn’t know where it will go on the plane,” Ronay said.
Such cases challenge the myth of plastic explosives’ enormous power. Although it is easily concealed, stable and packs about twice the force of other commercial explosives, plastic explosives hidden in luggage would not be enough to touch off a 747’s fuel tanks, Ronay said.
“If it was a bomb, I’m inclined to say you’d have something involving an explosive device concealed in the engine cowling or wing assembly,” Ronay said. “If the engine explodes, you could break the wing and release the fuel.”
The ability to plant a bomb so precisely would raise the stakes of terrorism, calling into question issues of personnel checks on maintenance staff and security provided for jetliners.
But Barr cautions it is too early to draw conclusions.
“Amateur investigators look at things they know have happened in the past and try to set this accident into a sequence they know,” he said. “Professional investigators have to keep an open mind. This could be a brand new problem a 747 never had in its history. Eventually we will find out.”
MEMO: This sidebar appeared with the story: ALSO MONDAY Searchers found a large piece of the wreckage of Flight 800 and had seen at least six bodies inside. Nearly 1,000 people gathered for a memorial service on an oceanfront bluff at Smith Point Park, one of the points of land nearest the crash site off the southern shore of Long Island. A New York Post reporter was arrested for impersonating a mourner for two days at the Ramada Plaza Hotel, the gathering spot for relatives of those who died in the TWA crash. The reporter, Tonice Sgrignoli, 43, was charged with criminal impersonation, trespassing, petty larceny and possessing stolen property. - Associated Press