Multitude of causes lined up for crash of Flight 111

By Stephen Thorne

OTTAWA (CP) _ The disastrous crash of Swissair Flight 111 on the night of Sept. 2, 1998, was not the result of a single damaged wire, a moment's lapse of judgment or a chance encounter with fate. Like so many disasters before it, the tragedy that claimed the lives of all 229 people aboard the MD-11 jet was born of a chain of events and failures _ all of them, ultimately, human. Aged and volatile electrical wiring. A taxing new inflight entertainment system. A fuselage lined with highly flammable insulation blankets. A veteran pilot with a Germanic devotion to the book. And a flawed book. Remove any one and the chain collapses. Swissair Flight 111 passes quietly through the darkness unnoticed off Peggy's Cove, landing in faraway Geneva. Those left behind to mourn their mothers and fathers, husbands and wives, sons and daughters, sisters and brothers can at least take some comfort, however small, in the thought they might not have died in vain.

Chances are that had Swissair not happened, factors that figured in the plane's demise would have happened elsewhere, causing other deaths. The fact it did happen may prevent future disasters. Regardless of whether Canada's Transportation Safety Board, working out of hangars at the Shearwater air base near Halifax, is ultimately able to point fingers, it is clear the industry already knew about some of the factors that felled Flight 111. Airlines immediately began taking steps to eliminate some links in the Swissair chain and pilots worldwide have begun to change they way they fly.

The investigators' preliminary findings have spawned a handful of airworthiness directives from the powerful, notoriously sluggish U.S. Federal Aviation Administration aimed at particularly vulnerable areas of electrical wiring and at volatile thermal and acoustic insulation blankets. The speed with which the FAA, the industry's lead regulator worldwide, has responded to the Swissair crash appears unprecedented. For the first time, the agency has ordered what it says are comprehensive checks of wires aboard older aircraft. It has appointed wire expert Ed Block, long a thorn in the side of complacent regulators, to important committees. As a result of advisories from Canadian investigators, it has found chafed and worn electrical insulation on wires aboard at least a dozen of the world's 178 MD-11s. But look again. In an industry where it is often said the fox is minding the chicken house, airlines maintain their own strong presence on FAA committees and in political backrooms where legislation is drafted and real decisions are made. Block has continued to run into hurdles as he's tried to move the issue of aged wiring up the regulatory agenda. After a two-month battle with FAA officials and industry representatives, he has managed to strike a subcommittee to investigate the relationship between insulation type and the wire problems that keep turning up. During the process, the former U.S. Defence Department adviser says his credibility has been questioned, his expertise challenged, and his welfare threatened. Meanwhile, some of the FAA orders ring hollow. They require only single checks for continuing problems such as chafed wires, or they call for removal of insulation bats from near-obsolete aircraft built by McDonnell Douglas, a company now owned by Boeing. 

The problem is not new. The Swissair disaster has its roots in a December 1981 memo issued by the U.S. Navy Department ordering replacement of wires wrapped in insulation made from polyimides, organically based materials that are susceptible to breakdown from humidity, handling and vibration. The polyimides, especially one known by its Dupont trade name Kapton, became volatile when, once bare wire was exposed, it arced _ tiny, lightning-like jumps from wire to wire. Sometimes, arcing would send spurious signals to cockpit instruments or, worse, to avionics like wing flaps or landing gear. Often, it would trip a circuit breaker. A pilot's natural inclination was to re-engage the circuits. But the practice proved fatal with Kapton. The surge from a new flow of electricity feeding an exposed wire wrapped in Kapton could cause what's known as a flashover, a sudden 5,000-degree fire that could incinerate multiple circuits and anything else that got in the way. The navy replaced Kapton wire aboard some jets, retired others, and ordered its suppliers to use other materials. Other elements of the U.S. military followed suit to varying degrees, and so did Canada's.

 In the mid-1980s, the U.S. military formed a panel to visit commercial aircraft manufacturers and warn them of the dangers Kapton posed. They even made a video showing the phenomenon in laboratory tests. Their warnings fell on deaf ears, says the man who made the video. "The airlines just didn't want to know about the problem because if you don't know about the problem, you don't have to deal with it," said Robert Dunham, a retired aerospace engineer. The average commercial jet contains more than 100 kilometres of electrical wiring, much of it inside hard-to-get-at panels and behind other equipment. And Kapton is aboard hundreds of jets built before about 1995 MD-11s, MD-80s, Boeing 727s, 737s, 767s and DC-10s. "If they were to replace all of that wire, this would mean a major disassembly of the aircraft," said Dunham, responsible for wiring and related naval systems for 15 years. "You're talking big bucks, out-of-service time, etc., and they're just not going to do it. They wouldn't do it."

TWA did ask Boeing to stop using Kapton, but Boeing talked the airline out of it, says a former airline engineer. The official industry line, until very recently, was that the problem was unique to military aircraft, especially navy jets with their tightly packed wires, high-stress performance demands, and often damp environments. "They can do anything in a lab they want but until we see it turn up in an aircraft, there's nothing we can do," FAA spokesman Les Dorr said a few weeks after the Swissair crash. In 1991, however, the FAA issued an advisory circular _ a non-binding document _ warning airlines of the dangers associated with Kapton and advising against reintroducing currents to damaged Kapton wire.

"Each successive attempt to restore an automatically disconnected power source, or the resetting of an automatically disconnected circuit protection device, can result in progressively worse effects from arc tracking," it said. Block believes that Swissair pilot Urs Zimmermann, having reported smoke in the cockpit and choosing to dump fuel to lighten his load rather than land immediately, may have authored his own demise by methodically following the airline's smoke-detection procedure as he turned away from Halifax. The process involves rotating a dial that with each click shuts down first one of the plane's three circuits, then re-engages it as it shuts down another, and so on. In an extraordinary move in the face of more than $1 billion in lawsuits, Swissair recently modified its cockpit smoke procedures. "In close collaboration with the manufacturers, Swissair's operations department has decided to restrict the 'circuit breaker reset' procedure throughout its aircraft fleet," the company said in a statement. "Circuit breakers that are tripped during flight will no longer be reset and the circuit will be regarded as unavailable for the rest of the flight."

And following the lead of several other airlines, Swissair consulted with Boeing on its checklist procedures, which barely mentioned landing. "These deliberations revealed that an emergency descent is the best procedure for bringing an aircraft quickly into position to make an emergency landing." The decision followed publication of a document by Boeing acknowledging the shortcomings of trying to detect smoke in what could be dire circumstances and urging pilots to exercise their own "experience and sound judgment." The Boeing document also warns pilots not to waste valuable time dumping fuel if they determine an emergency landing is necessary. A hard landing with a heavy load should not be a concern at maximum takeoff weight, it said. "Stopping distance is the only real concern. But even then, consider whether you would rather be on the ground _ or in the air." Unconfirmed reports from the Transportation Safety Board investigation suggest co-pilot Stefan Loew, who was apparently flying the plane, favoured an immediate landing but was overruled by Zimmermann, Swissair's chief instructor, who may have had his head buried in a manual. "One person cannot do it all," Boeing said. "Maintain responsibility and control, but delegate duties." 

Swissair was also quick to distance itself from an inflight entertainment system installed with swift regulatory approval just eight months before the crash. It disconnected the high-tech equipment shortly after burned and damaged wires were found amongst the Swissair wreckage. The cutting-edge entertainment system offered inflight games, gambling and video on demand. Manufactured by U.S.-based Interactive Flight Technologies, it was tested and turned down by several other airlines, including Qantas and Alitalia. Officials have said it placed high demands on electrical systems. Families cling to the hope some lasting good will come of the disaster. David Evans, editor of the industry newsletter Air Safety Week, thinks it already has and will continue to. "The crash of Swissair Flight 111 is likely to be one of those seminal events that changes design practices and operational procedures throughout the airline industry," said Evans. "I think the tragedy did not so much raise new issues of air safety as to bring old problems into sharp focus. They have been lurking, literally, out of sight and out of mind. "A lot of good things will come out of this tragedy."