Candles in the Wind: The crash of Swissair flight 111

Note: this accident was previously featured in episode 4 of the plane crash series on September 30th, 2017, prior to the series’ arrival on Medium. This article is written without reference to and supersedes the original.

The full timeline and track of Swissair flight 111’s final minutes. (TSB)

On the 2nd of September 1998, air traffic controllers in Moncton, New Brunswick received a distress call from a Swiss MD-11 over the Atlantic Ocean. The pilots of the wide-body jet reported smoke in the cockpit, and controllers authorized them to divert to Halifax, Nova Scotia, on Canada’s Atlantic coast. At first, no one seemed to be worried. But as the plane drew closer to Halifax, systems began to fail one after the other, plunging the pilots into a terrifying battle for survival. Flames burst into the cockpit; the radios went dead; the black boxes stopped recording. And yet for another six desperate minutes, the plane continued onward as though suspended outside of time — on board, 229 souls carried away into the unforgiving night.

Just after 22:31, Swissair flight 111 crashed into the sea near Peggy’s Cove, Nova Scotia, killing everyone on board. But how could a relatively new airplane flying for a world class airline in 1998 catch fire and fall from the sky? Investigators who tried to answer this question were faced with an airplane lying on the sea floor in millions of pieces, of which just one or two would explain the origin of the fire. And yet, through a herculean effort that turned into the largest air crash investigation in Canadian history, they found it: the single wire that started it all. In the process, the investigation shook the industry’s assumptions about in-flight fires, and revealed hidden dangers that threatened countless airline passengers around the world.

HB-IWF, nicknamed “Vaud,” the aircraft involved in the accident. (Aero Icarus via Wikimedia)

In the late 1990s, Switzerland’s flag carrier Swissair was in major financial trouble. The airline was losing money at a rapid clip, and a wide range of strategies meant to stem the losses had either failed to make any difference or backfired spectacularly. Among the measures taken to try to increase revenue was the installation of a new in-flight entertainment system on its long haul aircraft. Standard on big jets today but revolutionary at the time, the entertainment system allowed passengers in first class and business class to watch TV and movies, play games, browse the internet, gamble, watch the progress of the flight on a map, and more. Swissair was one of the first airlines to install such a system on its planes, and the first to do so on the McDonnell-Douglas MD-11, the pride of its long-haul fleet.

The approximate route of Swissair flight 111. (Google + own work)

It was one of Swissair’s three-engine MD-11s which was scheduled to operate a regular transatlantic journey from New York City to Geneva, Switzerland on the second of September 1998. In command were 49-year-old Captain Urs Zimmerman and 36-year-old First Officer Stefan Löw. In addition to the 215 passengers and 12 flight attendants, they would also be shepherding several high-value items, including a Picasso painting, two kilograms of diamonds, and 50 kilograms of currency bound for a Swiss bank.

With experienced pilots, a state-of-the-art airplane, and a world class airline that hadn’t had a major accident in nearly 20 years, the passengers and cargo alike should have had nothing to worry about. Indeed, as Swissair flight 111 climbed out from New York’s John F. Kennedy International Airport and headed east over the Atlantic Ocean, everyone settled in for what they thought would be a routine overnight flight.

Events in the first part of the flight. (Google + own work)

Around 15 minutes after takeoff, a bizarre event occurred which would later puzzle investigators. For 13 minutes, Swissair 111 did not communicate with air traffic control, a highly unusual gap for that phase of flight. Data recordings showed that the crew attempted to contact ATC eleven times during this period, and the regional controller in Boston attempted to contact the flight eight times before two-way communication was reestablished. Most likely, the pilots simply tuned their radios to the wrong frequency — a minor incident that as far as anyone knows had nothing to do with the events that unfolded later.

For another 30 minutes or so, flight 111 continued eastward at its cruising altitude of 33,000 feet. The crew said goodnight to Boston and conducted a routine handover to an area control center in Moncton, New Brunswick. It was not until 22:10 local time, as flight 111 cruised off the coast of Nova Scotia, that First Officer Löw noticed a strange odor in the cockpit.

A few seconds later, Captain Zimmerman spotted a few tiny wisps of smoke curling down from the ceiling near an air conditioning vent at the back of the cockpit. First Officer Löw, who was flying the plane, temporarily handed control over to Zimmerman while he got up from his seat to take a closer look. But by the time he got there, the smoke was gone. Unsure whether there was really a problem, Zimmerman decided to call the first class flight attendant up to the cockpit to provide a second opinion. Zimmerman asked whether she had smelled anything in first class, and she explained that she had not, but that an odor was definitely present in the cockpit. Zimmerman commented that it was “definitely smoke which came out,” but so far all signs pointed to a momentary contamination of the air conditioning system.

A diagram of the cockpit attic. (TSB, ignition point annotated by me.)

The pilots could not possibly have known that a fire had in fact broken out inside the cockpit ceiling. This inaccessible void, known as the attic, contains various structural elements, insulation, air ducts, and wire runs, but little else of note. It was certainly not a place where anyone expected a fire. But as flight 111 cruised high above the Atlantic Ocean, inside the attic a high-power wire supplying the new in-flight entertainment system suffered a failure that led to electrical arcing. In theory an arc should trip the associated circuit breaker, cutting off power from the affected systems. However, the circuit breakers on the MD-11 detected abnormalities based on a time vs. current correlation, which did not catch this particular arc as it fell within the normal “time-current curve.” Left unchecked, the arc soon met with a fuel source: insulation material designed to regulate the cabin temperature and reduce noise.

This thermal insulation blanket was wrapped in a thin sheet of metalized polyethylene terephthalate, more commonly known as Mylar, a versatile material used for everything from home insulation and fire protection blankets to nail polish and helium balloons. It takes considerable effort to ignite Mylar, but after some time, the electrical arc managed to do it. A tongue of flame appeared and began to spread across the insulation blanket. Smoke from the nascent blaze soon drifted down through seams in the cockpit ceiling, emerging near the air conditioning vent — a coincidence that initially misled the crew about the source of the problem.

One of the wires in the conduits in the lower image sparked the fire. It is unknown which conduit contained the faulty wire. (TSB)

After a shift in airflow temporarily pulled the smoke away, it seemed as though the problem had disappeared, and for a few moments the flight continued almost normally. But this proved to be a fleeting respite. Before long, the smoke returned, denser now, and it refused to dissipate. For the first time, the pilots considered the possibility that something was seriously wrong.

In the cockpit, the crew began examining their options for a diversion. They requested weather information from New York, Boston, and Moncton, none of which was particularly nearby. But the smoke had grown thicker again: “That’s not doing well at all up there,” Zimmerman commented, presumably looking back toward the area of the air conditioning vent. They needed to make a decision quickly.

At 22:14, Captain Zimmerman called Moncton control and declared “Pan, Pan, Pan,” one level of distress below “Mayday,” and tentatively asked that they be given permission to return to Boston, Massachusetts. Boston lay more than 500 kilometers behind them, but Captain Zimmerman knew the airport and it had a Swissair maintenance facility. The fact that these were his primary concerns showed that he did not consider the situation to be especially urgent. He had no way of knowing that a fire was burning in the hidden space just in front of and above the cockpit door.

The air conditioning smoke checklist used by Swissair. (TSB)

In response to Captain Zimmerman’s Pan, Pan, Pan call, the controller cleared flight 111 to turn back toward Boston. Although the smoke was not especially thick or irritating, the pilots felt it prudent to prepare their oxygen masks, a significant escalation of the situation. But before they could put the masks on, the Moncton controller asked if they would prefer to divert to Halifax, Nova Scotia, which was only 103 kilometers away — much closer than Boston. The pilots quickly agreed, and at 22:15, First Officer Löw initiated a descent of 2,000 feet per minute.

Now wearing their oxygen masks, the pilots guided the plane smoothly toward Halifax. Despite the smoke, all systems were working normally and no fire alarms had activated. Still displaying no great level of urgency, Captain Zimmerman informed the flight attendants that they would be landing in Halifax in 20 to 30 minutes, that he was starting work on a checklist, and that they should brief the passengers on the diversion. He was probably looking at the checklist for air conditioning smoke, which presented him with a number of methods that could be used to find its source, but evidence indicates none of these methods were used.

Meanwhile, the controller cleared flight 111 to descend to 3,000 feet, but First Officer Löw replied that they would remain at 8,000 feet in order to give the flight attendants more time to prepare the cabin. The controller also informed them that he was lining them up for runway 06, and that they were 55 kilometers from the airport. Löw told him that they would need more than this in order to descend to the runway.

Air conditioning ducts near the cockpit, showing areas which were found to be affected by fire. (TSB)

Part of the problem was that the plane was so loaded with fuel that it was over its maximum landing weight. Landing without first dumping fuel could damage the airplane, but was permissible in an emergency; however, the pilots didn’t believe the situation warranted such drastic measures. At 22:21, Löw informed the controller that they would like to dump fuel, and asked where would be a safe place to do this. Fuel is usually only dumped over water so as not to harm people on the ground, but by this point flight 111 was over land. To get the plane to a suitable dumping site, the controller cleared them to turn toward St. Margaret’s Bay, southwest of Halifax.

At 22:22, flight 111 leveled off at 10,000 feet and began preparations to jettison fuel. Shortly afterward, Captain Zimmerman started working through the “smoke of unknown origin” checklist, which instructed the pilots to cut electricity to the cabin. In the passenger cabin, the lights suddenly went out — the first indication for the passengers that something was seriously wrong. But this action also came with unintended consequences. Switching off the cabin electrical bus also disabled the recirculation fans, which until that point had been drawing the fire rearward into the attic above the galley. Now the airflow reversed direction, pushing the fire forward, toward the delicate avionics hiding in the ceiling above the pilots’ heads.

Heat-damaged structural elements in the cockpit ceiling. (TSB)

Just moments earlier, the fire had broken through the wall of an air conditioning duct, introducing a major new source of oxygen that fueled its rapid expansion. Beginning 24 seconds after Captain Zimmerman switched off the cabin electrical bus, the fire started to destroy one system after another. First the autopilot failed, tripping off with a loud ‘autopilot disconnect’ warning. As the crew scrambled to take manual control of the airplane, both pilots keyed their microphones and simultaneously broadcast separate mayday calls to air traffic control, indicating that they were declaring an emergency and needed to return to the airport immediately.

As Swissair 111 prepared to turn back toward the airport, more alarms began to blare. One of the yaw dampers failed; one of the two flight computers lost power; the flight data recorder started to shed parameters as it lost contact with various sensors. One second after the controller acknowledged the mayday call, the plane’s transponder stopped broadcasting; flight 111’s altitude and identity information disappeared from the controller’s radar screens. Seconds later, the VHF radio failed, cutting off a transmission from the plane in mid-sentence. Somehow, as systems failed around him, First Officer Löw held the plane steady, still heading south over St. Maragaret’s Bay. But Swissair flight 111 was out of time.

The full timeline and track of Swissair flight 111’s final minutes. (TSB)

The controller tried twice to contact the flight to give them permission to dump fuel, but there was no reply from the crew; in fact, he would never hear from them again. Amid the escalating cascade of failures, Captain Zimmerman shouted that something was “already burning,” as the fire burst through the ceiling and entered the cockpit. Löw exclaimed that all his instruments were going dark; peering through the smoke, he switched to the tiny standby instruments on the center console. One second after that, the other yaw damper failed, followed seven seconds later by both the flight data recorder and the cockpit voice recorder.

Like a ghost suspended outside of time, Swissair flight 111 continued to fly for a further six minutes, completely cut off from the world. Little is known about what happened after the black boxes failed, but the physical evidence left a few tantalizing glimpses into the pilots’ final, desperate fight to save their plane. Captain Zimmerman got out of his seat, perhaps to fight the fire, which came roaring through the circuit breaker panel at the back of the cockpit. Someone attempted to beat back the flames using the quick reference handbook of emergency procedures, causing the laminated pages to melt together. Zimmerman never returned to his seat; either he fought the fire to the end, or was overcome by smoke and flames.

On the ground, witnesses in coastal communities around St. Margaret’s Bay saw the plane pass low overhead, and some perceived it to be dumping fuel. Someone attempted to restore the instrument displays by switching the main electrical source; this caused the plane’s transponder to come back to life for 14 seconds, but then it failed again. First Officer Löw at some point shut down the center (#2) engine, probably because the blaze triggered an erroneous alarm; a heat-damaged book of checklists was found open to the procedure for an engine fire.

In the final minute of the flight, conditions grew even more dire as the hellish inferno literally melted the cockpit ceiling, splattering liquid aluminum over the observer’s jump seat. By now First Officer Löw was likely either seriously injured or dead as the intense heat destroyed the cockpit around him.

To the very end, most of the passengers probably never knew that the plane was on fire. No traces of smoke were found aft of first class, the plane did not appear to be out of control, and there was probably no announcement of an imminent crash landing or ditching. One first class passenger who was a certified pilot put on his life vest, apparently believing that a ditching was imminent; however, if Zimmerman and Löw ever considered putting the plane in the water, no evidence for it was found.

In the final seconds of the flight, the MD-11 made a right turn over the sea before apparently entering an inverted dive, plummeting at high speed toward the water below. What exactly sent flight 111 into this death dive will probably never be known. The fire might have killed both pilots, or perhaps, with no instruments and a cockpit filled with smoke, First Officer Löw became disoriented and lost control of the plane. Regardless, all hope for the passengers and crew had long since vanished. At 22:31 and 18 seconds, Swissair flight 111 plowed into the dark Atlantic Ocean, pitched 20 degrees nose down and in a steep right bank, traveling at over 550 kilometers per hour. In an instant, the aircraft disintegrated, snuffing out 229 lives — and the fire that claimed them — like so many candles in the wind.

An animation of Swissair 111’s final moments, as seen in the TV show “Mayday/Air Crash Investigation.” Note that the show portrayed the plane banking the wrong way.
People left mementos near the lighthouse in Peggy’s Cove. (Jonathan Hayward)

No one saw the MD-11 hit the water, but in the nearby village of Peggy’s Cove, plenty of people heard it. Air traffic controllers, who had watched helplessly as flight 111’s ghostly radar return tracked for six minutes before disappearing, soon received the news they had dreaded: the plane appeared to have crashed into the ocean about 10 kilometers off Peggy’s Cove. Fishermen who rushed to the area found only shattered debris and mutilated bodies; it was clear that no one could have survived.

As investigators from the Transportation Safety Board of Canada began arriving in Nova Scotia, one question possessed them: how could a fire bring down a modern jet flying for a world class airline with all the advanced fire protection systems that such status afforded? They would eventually discover that those protections were not as robust as everyone thought — but first, they had to complete the most difficult accident investigation in Canadian history.

Footage of the wreckage of Swissair 111 on the ocean floor. (Mayday)

The problem was that the MD-11 now lay in several million pieces at the bottom of the ocean, a massive jigsaw puzzle that had been thrown out into a watery wilderness. At first divers brought up pieces of the plane from under 55 meters of water, but as the autumn weather began to worsen, the divers were replaced with a trawling operation. That effort in turn gave way to a comprehensive dredging of the sea floor that continued until December 1999, eventually recovering an incredible 98% of the airplane by weight. (However, no trace of the Picasso painting, the diamonds, or the cash was ever found.)

The debris was brought to a hangar, where the TSB painstakingly identified and sorted more than three million pieces. Wreckage identified as being from the cockpit area was then carefully arranged onto a mockup frame, slowly reconstructing the area where the fire began. Experts simultaneously sorted through thousands of meters of wiring, carefully examining every last scrap for evidence of electrical arcing. A number of wires with arcing damage were found, but through a process of elimination, all but one were determined to have arced as a result of the fire. The last remaining wire supplied power to the in-flight entertainment system and was located in the aft right corner of the cockpit attic, within the fire-damaged area. Testing showed that a fire beginning here fit all the known conditions on board Swissair 111. Although it was impossible to prove conclusively, investigators felt it was highly likely that this was the particular wire which started the blaze.

The reconstructed cockpit of Swissair 111. (The Canadian Press)

It was not possible to determine the specific reason why this wire experienced electrical arcing. An examination of Swissair’s fleet found some quality assurance deficiencies, but no systemic problems with wiring maintenance. But regardless of the cause, an arc such as this should not have sparked a deadly fire.

At the time, aircraft fire protection systems were designed around three so-called “fire zones.” The first zone contained areas such as the engines, where combustion occurs in the course of normal flight; the second zone covered areas where accidental ignition is relatively common, such as the lavatories, wheel wells, and cargo holds. All areas in these first two zones were required to be equipped with smoke alarms and extinguishing devices. The rest of the aircraft fell into a third zone, where fires were thought to be very unlikely. In these areas, detecting and putting out fires depended on the prompt action of the flight attendants using the handheld fire extinguishers. Investigators would find that assumptions made about the relative risk of these various fire zones helped lead to the crash of Swissair 111.

In Geneva, someone took this photo of an arrivals board listing flight 111 as “delayed.” (Stéphane Ruet)

The cockpit attic, where the blaze began, was part of the third fire zone, because there was no history of fires occurring there, nor was it thought to contain any sources of fire risk. But a fire in the attic, were it to somehow occur, violated the principle of the third fire zone: namely, that the crew could easily detect it and put it out. There is no easy way to access the attic, and smoke from a fire in this area may not become visible until a blaze is already well underway. Without any fire or smoke alarms installed in the attic, and no way to extinguish a fire in this hidden space once it had started, there was little to stop a fire there from spreading out of control.

As it turned out, the attic was also not as fireproof as was previously assumed. Testing showed that the Mylar sheets around the insulation blankets were capable of propagating flame and could be found within close proximity of various wires, including those belonging to the in-flight entertainment system. Investigators believe that the arc from the failed wire ignited an adjacent Mylar sheet, allowing the fire to spread exponentially.

A piece of the plane is recovered, showing the registration: HB-IWF. (New York Daily News)

Metalized polyethylene terephthalate (MPET or Mylar) complied with all flammability requirements extant at the time. The material was required to withstand the application of a Bunsen burner flame oriented vertically for twelve seconds without catching fire; if it did catch fire it could still pass if the fire quickly self-extinguished. The Mylar sheeting passed the Bunsen burner test because it did not catch fire after twelve seconds. However, these tests failed to elucidate the fact that if it did catch fire, Mylar would not self-extinguish.

McDonnell Douglas produced numerous aircraft fitted with Mylar-coated insulation blankets between 1981 and 1994; Boeing also used it on some airplanes. However, in 1994 and 1995 a series of seven aircraft fires (six on the ground and one in the air) occurred in which these Mylar sheets ignited for various reasons. Upon investigating two of these incidents, the Civil Aviation Administration of China discovered that the sheets would burn up completely if ignited, and urged that the US Federal Aviation Administration ensure the findings received a “prompt response” by aircraft manufacturers.

After conducting its own tests using a flaming cotton swab coated in oil, McDonnell Douglas also concluded that Mylar could ignite and propagate flame. In 1997, the company put out a service bulletin recommending that operators remove Mylar insulation sheets from their aircraft; however, this was not mandatory, and despite urging by the CAAC, the FAA took no action against the material. By the time of the Swissair disaster, hundreds of airplanes fitted with Mylar insulation sheets were still flying all over the world.

Top down view of the reconstructed cockpit, probably while it was in progress. (Lectromec)

Once the Mylar ignited, the fire on board Swissair 111 spread quickly, consuming other nearby materials, such as plastic end caps, brackets, fasteners, tape, adhesives, and various foams. This generated smoke, which was diluted by cabin air diffusers before seeping into the cockpit. If this smoke had appeared anywhere other than where it did, it probably would have caused considerable alarm, but by coincidence it emerged right next to an air conditioning vent. As a result, the pilots misidentified it as air conditioning smoke. History had shown that smoke in the air conditioning system is often transitory and not a sign of a serious problem; as such, pilots were trained to isolate the source and ensure it went away. Training simulations gave the impression that these measures would always be successful. But this philosophy rested on the faulty assumption that pilots could actually distinguish between smoke from the air conditioning system and smoke from a fire. In practice, such a distinction was often impossible to make.

When they misidentified the source of the smoke, Captain Zimmerman and First Officer Löw reacted with less urgency than they would have if they knew about the fire. Their actions throughout the next ten minutes of the flight, from initially requesting to return to Boston to leveling off while the flight attendants cleared the cabin to circling away from the airport to dump fuel, all testified to this lack of urgency. Based on the information available to them, the threat from the smoke seemed to be less important than the threat of injury to passengers if they rushed to an overweight landing with an unprepared cabin. Even the checklist for “smoke of unknown origin,” which Captain Zimmerman opened only late in the diversion, emphasized determining the nature and source of the smoke before committing to an immediate emergency landing. In fact, this checklist would have taken 20–30 minutes to complete — longer than the time it took for the fire to destroy the airplane — and landing was the last item on it.

The cockpit interior, reconstructed by the TSB. (Toronto Star)

To put this in perspective, a study was carried out of 15 in-flight fires between 1967 and 1998 to assess the average time before a fire overcame an aircraft. In these cases, the time between first detection of the fire and the eventual ditching, forced landing, or crash ranged from 5 to 35 minutes, with an average of 17 minutes. On Swissair 111, just under 21 minutes passed between the first sign of smoke and the crash, a time that was approximately average compared to other in-flight fire events. Therefore the expectation that pilots would work through a smoke checklist requiring more than 20 minutes to complete was plainly unrealistic, and probably even dangerous. Indeed, it seemed that in every area, the procedures and philosophies used to approach in-flight fires were not designed for a worst case scenario.

The reconstructed cockpit interior, looking aft. (Global News Canada)

However, calculations showed that on Swissair 111, all of these deficiencies probably made no difference. The TSB found that if flight 111 had begun descending toward Halifax at the moment of the “Pan, Pan, Pan” call, and continued straight to the nearest runway without any deviations, the earliest it could have landed was approximately 22:27. Beginning the descent earlier would not have resulted in an earlier landing time due to the extra distance covered, and descending later than this (as they did in the actual event) would cause a later arrival time because the plane would be too high for a straight-in landing.

On the actual flight, by 22:27 numerous systems had failed, including all of the primary instruments, the autopilot, the flight computers, and many other critical pieces of equipment. Fire was already burning openly inside the cockpit, and Captain Zimmerman had probably already left his seat for the last time. Under these conditions it would have been impossible to land the plane, especially at night and in poor visibility. Furthermore, evidence indicated that the fire had by this time most likely disabled the slats, ground spoilers, auto-brakes, and anti-skid systems, meaning that even if the pilots somehow managed to land the plane, it would have been impossible to stop on the runway. The TSB was forced to conclude that even if the pilots had immediately recognized the problem and headed straight for Halifax, they would not have managed to save the plane.

TSB representatives give a press conference in front of the reconstructed cockpit. (Andrew Vaughan)

The official report on the crash noted that when Captain Zimmerman turned off the cabin bus switch, cutting power to the passenger cabin as prescribed in the “smoke of unknown origin” checklist, the recirculation fans stopped, allowing the fire to spread rapidly into the cockpit. The report did not explain whether the avionics failures would have been delayed if he had not done this. However, by that point it seems that the fire was so large that it would inevitably have reached these same aircraft systems a short while later. Furthermore, given that switching the cabin bus switch to “off” was the first item on the checklist applicable to their situation, it was not reasonable to expect that Captain Zimmerman would have neglected to do this in any conceivable scenario.

However, in the process of investigating the cabin bus switch, the TSB did find a shocking hidden design flaw. Moving this switch to “off” was supposed to cut electrical power to everything in the cabin in the event of an emergency. But on Swissair’s MD-11s, this action would not cut power to the in-flight entertainment system. The system was supposed to be connected to the main cabin electrical bus, but late in the installation process it was discovered that it drew too much power, and the American contractor, Santa Barbara Aerospace, decided at the last minute to connect it to a different electrical bus instead. This violated the MD-11’s electrical design philosophy, in which non-essential systems were connected to the cabin bus in order to easily shed them in an emergency. Early in the investigation it was thought that an overheating in-flight entertainment system could have caused the fire, in which case this design error would have played a central role in the sequence of events. However, it turned out that Captain Zimmerman didn’t switch off the cabin electrics until the fire was already well underway, by which point it made no difference that the entertainment system remained powered. Despite this, the finding set off a side investigation of Santa Barbara Aerospace, which eventually resulted in the company getting shut down by the FAA for unsafe practices.

The fragmentation of the wreckage attests to the tremendous force of the impact. (CBC)

By the later stages of its investigation, the TSB had determined that Swissair 111 was doomed from the moment the fire broke out. If a nearly random arcing event could bring down a modern airliner, leaving the crew with no recourse, then the crash could have happened at any airline, and could yet happen again. In fact, the Swissair fire had systematically defied nearly every expectation built into aircraft fire protection systems. It was clear that the aviation industry’s entire approach to fire safety needed to be reexamined.

In 1999, acting on a TSB recommendation, the FAA ordered wiring inspections on all MD-11s. At several airlines, the inspections turned up numerous cracked, chafed, or otherwise damaged wires, prompting the FAA to launch a massive effort to bring MD-11 wiring up to code and update wiring-related training for government inspectors. In 2000, again on the urging of the TSB, the FAA mandated the removal of all Mylar insulation sheets from aircraft, as well as several other insulation materials which failed the agency’s new, more stringent flammability tests. Today, all insulation materials used on airplanes must be shown not to ignite or propagate flame even when directly exposed to a localized source of heat or fire.

Recovery crews remove pieces of Swissair 111 from the ocean. (Carlo Allegri)

The TSB also sought to make sure flight crews around the world were ready to handle the next in-flight fire. The agency recommended that the existing fire zones be re-evaluated; that emergency checklists for fire and smoke contain few steps and emphasize landing immediately; and that flight attendants learn how to fight a fire in any part of the airplane, even in hidden spaces, by breaking through cabin interior panels. Acting on the recommendations, Swissair completely overhauled its training program for fire emergencies and rewrote its fire and smoke-related checklists. The FAA launched a program to prepare a similar overhaul for all US carriers. Boeing, which had by this time taken over production of the MD-11, took action as well, planning an upgrade which would include smoke detectors in the attic and avionics compartment, changes to the wire routing, and the installation of cameras so pilots could see hidden areas of the plane.

However, Swissair itself did not last long enough to see most of these changes through. A series of bad investments and costly lawsuits surrounding the crash put the airline on the brink of insolvency, and then the global aviation downturn after the 9/11 attacks finished it off. Swissair declared bankruptcy in 2002, and its assets were sold to its competitor Crossair, ending the 71-year history of Switzerland’s storied flag carrier.

Residents of Peggy’s Cove put up signs along the highway expressing solidarity with the families of the victims. (New York Daily News)

In its final report, the TSB also asked for changes which would help future investigations. Investigators recommended that cockpit voice recorders produce better quality recordings and keep at least two hours of conversation rather than 30 minutes, an improvement which is standard today. (As of 2021, the International Civil Aviation Organization is now recommending that manufacturers increase this further, to 24 hours.) The TSB also recommended that the black boxes contain backup batteries so that they can continue to record even after a total loss of electrical power, and that airlines consider installing cockpit image recorders; however, neither of these has been implemented.

Although the TSB felt at the time that much work remained to be done to ensure airliners were safe from in-flight fires, looking back 23 years later, it is clear that Swissair 111 has led to a sea change in the way everyone from pilots to regulators approaches the threat. Today, it’s hard to imagine a pilot reacting to visible smoke with anything other than an immediate diversion to the nearest available airport. At the back of everyone’s mind is the gnawing question: could this smoke be the start of the next Swissair 111? No one is willing to take that risk.

But while airplanes today are much more fire-resistant than in 1998, and pilots understand the true danger, as long as airplanes contain both ignition sources and fuel, in-flight fires will occasionally occur. As if to prove the point, in 2016 EgyptAir flight 804, an Airbus A320, crashed into the Mediterranean Sea, killing all 66 people on board, after a rapidly spreading fire ignited inside the cockpit. Although political disputes and corruption in Egypt have so far prevented the completion of the investigation, it is thought that the fire might have originated from improperly maintained cockpit avionics, or from one of the pilots’ personal electronic devices. In any case, the fire overwhelmed the crew within two or three minutes, precluding any possibility of a safe landing. The suddenness with which the disaster befell the ill-fated jet underscores the continuing danger posed by even unlikely ignition sources.

The memorial to the crash victims in Peggy’s Cove. (CTV News)

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On a windswept hill above Peggy’s Cove, a memorial to the victims of the Swissair tragedy gazes out over the unsettled Atlantic waters. On a stone plaque are inscribed the words: “In memory of the 229 men, women, and children aboard Swissair flight 111 who perished off these shores, September 2, 1998. They have been joined to the sea and the sky. May they rest in peace.” We will never know for sure what those people experienced as Swissair 111 flew away into the darkness for the last time. We will never know the details of the pilots’ last, heroic efforts to save the lives of their passengers, even as a horrific inferno bore down upon them. And yet, although their final words and deeds were lost to the eternal ocean, the echoes of the tragedy still reverberate today, from Geneva to Peggy’s Cove to Washington D.C., not just in the lives of those who were affected, but in the lives of everyone who flies. Indeed, we all should spare a thought for those 229 souls whenever our flight arrives safely at its destination.

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Analyzer of plane crashes and author of upcoming book (soon™). Contact me via @Admiral_Cloudberg on Reddit or by email at kylanddempsey@gmail.com.