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Dissection of a Disaster


Crash of Flight 111 homepage

The search for the cause of the fire that brought down Swissair Flight 111 on the evening of September 2, 1998, killing all 229 people aboard, took over four years and cost $39 million. It was one of the most exhaustive airline crash investigations ever mounted. In this interview, airline safety expert David Evans takes an authoritative look at the investigation and what he calls a "confederacy of complacency" in the airline industry regarding safety improvements following this and other major accidents. The interview was conducted in October 2003 at the offices of Air Safety Week, a widely respected airline safety newsletter that Evans edits.

NOVA: What was known in the immediate aftermath of the crash?

Evans: Well, based on the conversations between the pilots and air traffic control, the initial indications were that they had some sort of a smoke event on the airplane. We know that the crew had declared a Pan, which is a technical problem on the airplane that affects safety. And moments before the final crash, they declared a Mayday. What was initially known was a loss of control.

NOVA: So the crew knew there was a fire?

Evans: If we look at what the crew was experiencing as they were flying along on this nighttime flight, we have to note that smoke and fire events on aircraft can be seductive. I mean, you've got a sort of a whiff of something, and then you're going through a procedure, trying to determine where this smoke is coming from. In pilots' parlance, the situation is known as Smoke and Fire of Unknown Origin.

I think that the final horror of their grim situation may not have been fully appreciated until the fire in the attic space over the cockpit burned its way through the ceiling panel, and Captain [Urs] Zimmermann was showered with the charred effects of the fire, the burned plastic, the sudden blast of heat. At that point, I think that that eruption of hot gas and possibly flame into the cockpit pushed him out of his seat, because we do know that he was not in the captain's left seat at the moment the airplane collided with the water.

NOVA: How useful were the black boxes in the subsequent inquiry?

Evans: The cockpit voice recorder and the flight data recorder lost power about six minutes before the airplane finally crashed. These devices, the so-called black boxes, which are actually painted orange, are really the Rosetta Stones for an accident investigation, because they enable investigators to recreate the sequence of cascading failures, what the crew was doing, what they were saying to each other, and also the wealth of systems data that is captured on modern black boxes.

“Clearly we had an uncontrolled, uncontained, runaway fire on this airplane.”

It's of interest that in the course of this investigation, the Transportation Safety Board of Canada (TSB), which had primary responsibility for the investigation, issued safety recommendations calling for improved black-box capability and an independent power supply so that if the aircraft lost electrical power, they would keep on catching any data that was there to be had. They also called for dual installation, so that you'd have a fully redundant cockpit voice and flight data recorder capability located both in the nose and in the aft part of the airplane.

NOVA: Have those recommendations been acted upon?

Evans: The TSB issued its recommendations for improved black boxes some three years ago now. Those recommendations, primarily calling for a two-hour recording capability so that they would have a better capability in the future for reconstructing accident scenarios, have not yet been acted upon by the authorities. Those recommendations have simply dropped into a regulatory black hole.


Working the evidence

NOVA: Without the black-box data, how did the TSB pursue its investigation?

Evans: The absence of good flight and cockpit voice recorder data obviously increases the difficulty of the investigation. Let's say on a scale of difficulty from zero to 10—zero being pretty straightforward, 10 being extraordinarily difficult—if you've got the black boxes and good data from them, the level of difficulty might be on the order of a four or five. Without the black boxes, you're talking a nine or 10 level of difficulty and trending towards unsupportable conclusions.

It really pushed the investigators back into sort of a secondary mode. They began looking at other sources of data: What could they capture from the non-volatile memory chips in the engines' digital recorders? How else could they look at this in terms of the physical evidence?

NOVA: What did they focus on?

Evans: Well, the investigators began focusing on the source of the smoke, because where there's smoke, there's fire. And clearly we had an uncontrolled, uncontained, runaway fire on this airplane.

NOVA: Did the mountain of evidence retrieved from the seafloor help them pinpoint the source of the fire?

Evans: Well, in the horribly grim circumstances of this tragedy, the one small footnote of good news perhaps, from an investigative standpoint, was that the airplane impacted into water, which had the effect of immediately dousing the fire and freezing in time the evidence that would be so crucial to unraveling the mystery. Had the airplane crashed on land, we probably would have just had a smoking, black, smeared piece of earth with some tiny pieces of aluminum and wire. It would have been much more difficult.

As it was, the investigators were able to recover the heat-damaged, charred wires, which were obviously burned from either electrical arcing or a runaway in-flight fire of some kind. Those wires led them to pursue the scenario of a runaway, uncontained, in-flight fire of electrical origin.

NOVA: What was known at the one-year anniversary of the crash?

Evans: By the one-year anniversary, the bulk of the wreckage had been recovered. The notion of an electrically stoked fire on the airplane had been pretty well established. The investigators were now facing a major effort to recreate the circumstances surrounding the fire: how it got started, how it took root, how it was able to ultimately bring this airplane down.

“I was thinking at the time: These things are flying firetraps.”

I think with respect to the impact on the families, the one-year anniversary is one of particular symbolism and perhaps personal pain. There's no closure in terms of the investigation. Who knew that this investigation would ultimately drag out to four years or more to put together all the factors, all the latent hazards, all the circumstances surrounding this tragedy? So at the one-year point, major safety themes were emerging, but we were a long way from closure in the form of justifiable conclusions.

NOVA: And what was happening at this point in the investigation?

Evans: At this point the investigators had an airplane that began life as four million parts flying in close formation, and now they had recovered virtually the equivalent of those four million parts, and those parts were in bins. They had a major challenge: what I would call forensic reconstruction of what occurred on the airplane. They determined to try and reassemble the cockpit. They created a steel frame, or skeleton, on which to mount recovered pieces of the airplane. They also began focusing in on the forward part of the cabin, including the attic space, the forward galley, and the cockpit, and on putting the pieces together—the panels, the aluminum, the wires, the electrical components—to try and recreate how this case progressed from an electrical incident to a major accident.

If we look at the amount of flammable material that the investigators recovered from the airplane and, to their dismay, finding how much of it was burned—the oxygen-line end caps, the thermal acoustic insulation blanketing, and other material—I was thinking at the time: These things are flying firetraps. I mean, how is it that we can put 200-plus people in an airplane with all this flammable material? This is the tinder waiting for the match. And the match, as we now know, was the electrical arcing. [Editor's note: The investigators concluded that electrical arcing—a discharge of electricity from a damaged cable—triggered a fire in the plane's insulation materials. The arcing occurred in the attic space just above and aft of the cockpit, possibly in bundles of wiring in that space.]


Taking action—and not

NOVA: Had this kind of fire ever been reported before?

Evans: Behind every major aviation accident is a history. In the case of Swissair Flight 111 and the thermal acoustic insulation blankets, the Chinese had experienced a number of cases of in-flight fire and damage in which the blankets had burned. And the Chinese authorities had contacted our Federal Aviation Administration (FAA) and advised them "Guys, you may have a flammability problem here." Action taken: None.

NOVA: What action did the TSB, for its part, take when this danger of fire became clear?

Evans: Well, by December of 2000, the Safety Board of Canada felt like it was dealing with a major problem: the vulnerability of aircraft to in-flight fires. And they had a press conference at which they expressed publicly their concerns—to wit, that collectively in the industry we have not done an adequate job of reducing the flammability and providing greater protection against in-flight fire.

NOVA: Did the TSB add this potential danger to its list of official recommendations?

Evans: Yes. The TSB has issued a number of very important recommendations to improve the safety of this airplane and of all airplanes. Those recommendations have been transmitted to the Canadian regulatory authorities and to our National Transportation Safety Board, which is the comparable accident investigation body to the Canadians'. Our Safety Board, to its great credit, has fully endorsed the Canadian recommendations and has sent them on to the FAA, which is the regulatory authority responsible for this airplane.

NOVA: Has the FAA endorsed the recommendations?

Evans: In terms of what the FAA is doing, let me cite the great British Prime Minister Disraeli: "We are making haste slowly."


Lessons

NOVA: So what would you say is the legacy of this case?

Evans: The legacy of this case is enormous, because we have a continuing problem with in-flight smoke and fire. I like to say that if the cabin of a modern jetliner was a restaurant, it would not get an occupancy permit, because you've got people in a confined space with no fire detection or suppression, and they're sitting on top of high-powered electrical circuitry and a big load of fuel. You have all this in very close proximity.

“We have what I would call a confederacy of complacency with respect to in-flight fire detection and suppression.”

Now, if we look at, say, rest homes, the mobility of old folks is likewise limited. Yet to get an occupancy permit for your parents' rest home, the builders and developers had to demonstrate that every square inch of that nursing home is covered by detection and suppression. We can look up in this office space here, and we can see the nozzles for the fire-protection system. You know that if we have an electrical fire in this building, we're going to be doused with a spray of water. We are fully protected, and yet we can get out quickly also. When you're in a jetliner at 30,000 feet, you're not getting out. You've got to fight it long enough to get the airplane on the ground.

Now, what do we have in the airline industry? We have what I would call a confederacy of complacency with respect to in-flight fire detection and suppression. The National Transportation Safety Board has said that we need an integrated firefighting philosophy on airplanes. Yet we've got spaces that we don't have access to that are not protectable by fire detection or suppression. So the hazard continues to this day.

NOVA: Do you think the apparent industry inaction on this front is due to a cavalier attitude about the value of human lives?

Evans: No. There is a phrase within the industry to the effect that "If you think safety is expensive, try an accident." So I don't see that at work here. What I do see are a combination of forces: complacency, bureaucratic inertia, "It's too hard," "We're not making money now," things of this nature.

What strikes me is that so many of these accidents about which I have written over the years had precursor events that, had action been taken with alacrity, if we had not been in the Rip Van Winkle mode of regulatory torpor, could have been prevented. So the issue to me is not whether you can fly for a thousand years before you're going to be involved, statistically speaking, in an aircraft accident. The question is: How many of these accidents were avoidable and preventable? I haven't seen one yet where structure and systems were involved where it wasn't avoidable and preventable beforehand. And therein lies the tragedy. Therein lies the culpability.

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David Evans

Veteran aviation reporter David Evans feels that all recent major aircraft accidents that involved systems or structure were preventable. Read on to hear his argument.











Zimmerman

Urs Zimmermann, the pilot of Swissair Flight 111, may not have known how serious the fire was until it burst into the cockpit.











Black box in cooler

Swissair Flight 111's flight data recorder shortly after its retrieval from the seafloor. Once they examined it, investigators discovered that it had stopped recording five minutes and 37 seconds before the crash, when the crew had turned off the plane's electrical power in its attempt to isolate and fight the fire.











Fire animation still

Investigators believe the fire started in the ceiling area near the cockpit. Initially it spread aft, but when the crew turned off all non-essential power to the cabin, this shut down the recirculation fans, causing the fire to surge forward.

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Reconstructed nose of airplane

When the investigators determined by studying parts retrieved from the seabed that the fire had been concentrated in the forward area, they painstakingly reconstructed that part of the plane to pinpoint the fire's origin.

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Insulation on fire

To investigators' surprise, the aircraft's thermal insulation blankets, which had passed an FAA test for fire safety, readily ignited in a test conducted during the crash investigation.

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Peggy's Cove

Peggy's Cove, Nova Scotia, off whose shores Swissair Flight 111 disappeared from radar on the evening of September 2, 1998.

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Crash of Flight 111
Wireless Black Boxes

Wireless
Black Boxes

Should airlines transmit flight and cockpit data to ground stations in real time?

Dissection of a Disaster

Dissection
of a Disaster

A veteran air-safety reporter turns an insider's eye on the Flight 111 investigation.

Making Air Travel Safer

Making Air
Travel Safer

Shocking as they are, major crashes lead to important safety improvements.

Anatomy of a Jetliner

Anatomy of
a Jetliner

Look inside a passenger jet at its sophisticated internal systems.



Interview conducted by Gary Glassman, producer of "Crash of Flight 111," and edited by Peter Tyson, editor in chief of NOVA online



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