A Song of Smoke and Fire: The tragedy of Air Canada flight 797

Note: this accident was previously featured in episode 35 of the plane crash series on May 5th, 2018, prior to the series’ arrival on Medium. This article is written without reference to and supersedes the original.

Air Canada flight 797 burns on the runway following its emergency landing in Cincinnati. (WLWT 5 News)

On the second of June 1983, the captain of an Air Canada DC-9 cruising at 33,000 feet over Kentucky received a disturbing report from the cabin crew: “Excuse me, there’s a fire in the washroom.” Those words would mark the beginning of a harrowing and controversial emergency, as the pilots struggled against failing systems and choking smoke which threatened the lives of everyone on board. And then, for a moment, it seemed like they had made it — after 17 minutes, Air Canada flight 797 touched down at Greater Cincinnati International Airport, rolled to a stop, and commenced an emergency evacuation. But as passengers packed the aisles, desperate to escape the smoke-filled cabin, the entire plane went up in flames, igniting from one end to the other in a matter of seconds. Of the 46 people on board, 23 lived, and 23 died — a devastating outcome for a flight that had landed safely just moments earlier. How could such a thing happen? It was in the effort to understand this needless loss of life, and to prevent it from ever happening again, that experts would develop many of the basic cabin safety systems and procedures which airline passengers now take for granted.

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C-FTLU, the aircraft involved in the accident. (Werner Fischdick)

Once in a long while, a manufacturer’s assembly line will for whatever reason spit out a plane which is simply cursed. C-FTLU, a McDonnell Douglas DC-9 operating for state-owned carrier Air Canada, was one of these. Built in 1968, C-FTLU had an unscheduled maintenance history a mile long, and even more notably, an accident history as well. The already cursed airplane’s problems escalated dramatically in 1979 when its rear pressure bulkhead, which separates the passenger cabin from the unpressurized tail section, failed explosively while climbing out of Boston. The powerful decompression blasted the tail cone off the airplane and damaged both the flight control cables and the cables transmitting pilot inputs to the plane’s rear-mounted engines. The pilots had to fight to get the plane down safely, but they made it, and no one was seriously hurt.

After the accident, the airplane was repaired and returned to service, but it was never the same. Although the cause of the difficulties was not conclusively pinpointed, numerous wires had to be cut and re-spliced to access damaged structure behind them, and it is thought that the quality of this electrical work may have been lacking. In any case, the result was that C-FTLU developed an unusually high rate of electrical problems, on top of everything else that was already wrong with it. By the late spring of 1983, the problem had become so bad that the auxiliary power unit alone was malfunctioning an average of 1.5 times per day.

The route of Air Canada flight 797, with Cincinnati also marked. (Google + own work)

The problems had still not been solved when, on the second of June, 1983, C-FTLU pushed back from the gate in Dallas, Texas, on its way to complete Air Canada flight 797 to Toronto and Montreal. In command was 51-year-old Captain Donald Cameron, a veteran pilot with over 13,000 flight hours, and 34-year-old First Officer Claude Ouimet, who had 5,600 hours, nearly half of them on the DC-9. They were joined by three cabin crew, consisting of lead flight attendant Sergio Benetti, №2 flight attendant Laura Kayama, and №3 flight attendant Judie Davidson.

In what would later be noted as a stroke of good fortune, the passenger load that day was relatively light. Only 41 passengers boarded the plane in Dallas, leaving the DC-9 less than half full — although the manifest’s star power was unusually heavy. In fact, one of the passengers was famous Canadian folk musician Stan Rogers, who was returning from a performance at the Kerrville Folk Festival in Kerrville, Texas. At the age of 33, Rogers was already arguably the most well-known folk singer in Canada, but by all accounts his career was still beginning, and his audience was growing rapidly, especially abroad. Although he was said to have hated flying, demand for his performances throughout North America was so great that he could hardly avoid it, and to be sure, taking a plane to his events was safer than driving.

Stan Rogers during a performance. (stanrogers.net)

Flight 797 took off from Dallas at 16:25 local time and climbed uneventfully to its cruising altitude of 33,000 feet. For an hour and a half it made its way northeast across Arkansas and into Kentucky, sending the clocks forward an hour. The flight attendants served drinks, and the pilots chatted over dinner. All the systems that were working on takeoff were still working.

And then, at 18:51, three circuit breakers on the panel behind Captain Cameron’s seat suddenly popped, one after another.

“What was that?” First Officer Ouimet asked.

“Damn,” said Captain Cameron.

“It’s right there, I see it,” Ouimet said, pointing to the breaker panel.

“Yeah, DC bus.”

“Which one is that?”

“DC bus, the uh, left toilet, left toilet flushing,” said Cameron.

Indeed, all three popped circuit breakers were associated with the toilet flushing motor in the rear lavatory, located on the left side of the plane behind the last row of passenger seats. The activation of the circuit breakers meant that for whatever reason, the toilet was inoperative. Hardly an emergency.

“I better try it again, eh, push ’em in,” said Cameron, reaching around to reset the circuit breakers.

“Push it in one more time, I guess,” said Ouimet.

But when Cameron pushed the breakers in, they immediately popped back out again.

“What!” Ouimet exclaimed.
“That’s it,” said Cameron. “Won’t take it.”

“No?”

“See anything else?” Cameron asked. “There’s nothing on the panel. Ha, like a machine gun.”

“Yeah, zap, zap, zap,” said Ouimet.

“Put it in the logbook there,” Cameron suggested. “Somebody must have pushed a rag down the old toilet or something, eh? Jammed it and overheated.”

If only the answer had been so simple! The truth, as it turned out, was much less funny. Far out of sight of the crew and passengers, a fire had ignited inside the floor beneath the amenities unit in the aft lavatory, and was slowly creeping its way through the hidden spaces behind the cabin walls. At some point it had reached and then melted the wire harnesses supplying power to the toilet flushing motor, causing the circuit breakers to pop.

For another eight minutes, there was no further sign of any problem. The pilots wrote down the fault in the logbook, made contact with Indianapolis Center, and chatted about the weather.

At 18:59, having waited long enough for the toilet motor to cool down, Captain Cameron tried again to reset the circuit breakers. One by one, he pushed each breaker back in, only for it to immediately pop back out again. “Pops as I push it,” he said. And that was that — if the toilet wasn’t working, it wasn’t working. Cameron turned away from the breaker panel and called lead flight attendant Sergio Benetti to order his dinner.

The layout of the aft lavatory on the DC-9. (Matthew Tesch for Macarthur Job’s “Air Disaster: Volume 2,” with reference to NTSB materials)

Meanwhile in the back, a passenger seated in the last row pulled №3 flight attendant Judie Davidson aside to ask about a strange odor which had begun to seep into the back of the cabin. Agreeing that there was an odd smoky or electrical smell in the air, Davidson retrieved a fire extinguisher and cracked open the lavatory door. To her surprise, she was immediately blasted by smoke, hovering thickly in the air and curling out of the seams between the wall panels. Despite the amount of smoke, however, she couldn’t see any fire to attack with the extinguisher. Eyes watering, she immediately closed the door and told №2 flight attendant Laura Kayama about what she had seen.

Moments later, Kayama passed the report on to lead flight attendant Benetti, and then to the pilots. Popping into the cockpit she said, “Excuse me, there’s a fire in the washroom, at the back, they’re just… went back to put it out.”

“Oh yeah?” said Captain Cameron.

“They’re still, well they’re just gonna go back now,” said Kayama.

“Want me to go there?” Ouimet asked.

“Yeah, go,” said Cameron.

“The breaker’s screwed up,” Ouimet add.

To Kayama, Cameron said, “Leave my dinner in the thing there for a minute.”

He didn’t know it yet, but the dinner that was prepared for him would never be eaten.

In the background, the cockpit voice recorder captured a passenger saying, presumably to another passenger, “Can I buy you a drink? Cause there’s something going on. Drink or a shot?”

If the reaction of the crew and passengers seems overly casual, it should be noted that in 1983, fires in aircraft lavatories were a relatively common occurrence. Although smoking in the lavatories had been banned since the mid-1970s, it was still allowed in the cabin, and passengers occasionally set minor fires by tossing improperly extinguished cigarettes into the lavatory trash bins. These trash bins are designed to contain a blaze, and on this particular DC-9 the bins were even fitted with automatic heat-activated fire extinguishers, so while such a fire would require a response, it would not necessarily have been an emergency, nor were pilots likely to treat it as one, unless it began to spread.

Captain Donald Cameron. (WLWT 5 News)

At the back of the plane, lead flight attendant Benetti took the fire extinguisher and opened the lavatory door. There was no sign of any flames, but smoke was pouring out of every conceivable orifice. Although he wasn’t sure whether it would make any difference, he emptied the contents of the fire extinguisher into lavatory, covering every inch of the tiny room, then closed the door.

In the cockpit, Captain Cameron put on his oxygen mask as a precaution, while First Officer Ouimet went back to assess the situation. By the time he got there, however, thick smoke had enveloped the last several rows, and he couldn’t even reach the lavatory. At that point he encountered Benetti, who described what he had seen, and conveyed to him his suspicion that this was no ordinary trash bin fire.

Up front, a flight attendant could be heard asking, “Captain, is it okay to move everybody up as far forward as possible?” With so much smoke in the back of the cabin, it was unwise to let passengers sit there, and with the plane less than half full, it was possible to move everyone forward of the wings if necessary. Captain Cameron apparently gave permission, because moments later the flight attendants began doing just that, moving everyone up to the first twelve rows.

Shortly thereafter, at 19:04, First Officer Ouimet returned to the cockpit and delivered his report. “Okay, I — uh, you don’t have to do it now, I can’t go back now, it’s too heavy,” he said. “I think we’d better go down.”

“I got all the passengers seated up front,” Benetti chimed in. “You don’t have to worry, I think it’s gonna be easing up.”

“Okay, it’s starting to clear now,” Ouimet agreed. Indeed, looking toward the back, it was evident that the smoke had all but disappeared from the rear of the cabin. Maybe the fire was out after all.

Just to be sure, however, Captain Cameron decided to send Ouimet back a second time, this time with smoke goggles, to go make sure that the fire was actually out.

“Okay, go back whenever you can, but don’t get yourself incapacitated,” Cameron warned.

“No problem, no problem,” Ouimet replied, heading back once more.

After he left, another flight attendant came in again. “Captain, your first officer wanted me to tell you that Sergio has put a big discharge of CO2 in the washroom; it seems to be subsiding alright.”

“Getting much better, okay,” Benetti added. “I was able to discharge half of the Co2 into the washroom even though I could not see the source, but it’s definitely in the lavatory.”

“Yeah, it’s from the toilet,” Cameron said.

“It[’s] now almost cleared,” Benetti continued.

But at that moment, First Officer Ouimet was finding that not all was as it seemed. Although he was able to reach the lavatory, the door handle was so hot to the touch that he was afraid to open it. Even though the smoke was gone, the fire must still have been burning, and that meant they had a serious problem.

Map of flight 797’s final 20 minutes, with significant radio calls and other events. (Matthew Tesch for Macarthur Job’s “Air Disaster: Volume 2,” with reference to Washington Post and NTSB materials)

Up front, Captain Cameron was about to discover the same. Just before 19:06, the master caution light illuminated, warning of a failure of the left AC and DC electrical generators — a major escalation of the situation. Recognizing that the plane could lose all electrical power at any moment, Cameron called Indianapolis Center and said, “We’ve got an electrical problem here — we may be off communication shortly, stand by.”

Retreating from the lavatory, First Officer Ouimet returned to the cockpit at 19:07, where he said to Captain Cameron, “I don’t like what’s happening, I think we better go down, okay?”

Moments later, at 19:07 and 41 seconds, the cockpit voice recorder and flight data recorder both ceased recording simultaneously. Shortly after that, the master caution light came on again, and the right and emergency AC and DC buses all lost power. With all the electrical buses out, most of the pilots’ instruments failed; their artificial horizons toppled over, dead as doornails. Thinking quickly, First Officer Ouimet reached up and flipped the emergency power switch, transferring the emergency AC and DC buses to battery power. This brought the instruments back online — for now at least.

Recognizing that they were suddenly in dire straits, Captain Cameron began a steep emergency descent, while First Officer Ouimet radioed Indianapolis center and declared an emergency, telling the controller that flight 797 had a fire on board and was going down. The controller noted that flight 797 appeared to have lost its transponder, which provides identity and altitude information; as a result, he had to switch to primary radar to track it. After identifying the plane, he replied that the nearest airport was Cincinnati, less than 25 nautical miles to the northeast. Starting from 33,000 feet, the pilots would have to push the descent to get down in time to land there.

Although Captain Cameron managed to achieve a descent rate of over 5,000 feet per minute, it took intense strength and concentration to do so. In fact, due to the escalating failures, he had lost control over the horizontal stabilizer, which normally would have allowed him to “trim” the plane to hold a nose down position. With the stabilizer still set for cruise flight and unable to move, the only way for Cameron to maintain a descent was by continuously holding his control column forward with considerable force, using the elevators to overpower the stabilizer.

How smoke spread through the cabin. (Matthew Tesch for Macarthur Job’s “Air Disaster: Volume 2”)

Meanwhile in the cabin, the smoke had returned with a vengeance. When it seemed to be clearing, passengers had gone back to drinking and chatting as though nothing was wrong, but shortly after the start of the emergency descent, the smoke swept in from the back of the plane and rolled all the way down the passenger cabin, clinging to the ceiling. Before long, it poured in through the open cockpit door and enveloped the pilots as well.

Although the crew had full-face oxygen masks which could protect them from the smoke, the passengers did not. Not only do passenger oxygen masks provide no barriers against smoke, Air Canada rules forbade their use with a fire in board, because the mass release of oxygen could provide additional fuel. As a result, the passengers were fully exposed to the acrid smoke, which attacked their eyes, throats, and sinuses with caustic ferocity. Doing their best to help, the flight attendants instructed the passengers to breathe through a damp cloth; briefed able-bodied passengers on how to open the overwing exits; and administered oxygen from one of the portable bottles to a person who was having particular difficulty breathing. But there was only so much they could do: as the smoke got thicker and blacker, the passengers grew weaker, and the fear of death crept over them. Some people started writing notes to loved ones; one man recalled placing his ID in a secure pocket so they could identify his body.

At the same time, the pilots and controllers were working to get the plane into Cincinnati as quickly as possible. The Indianapolis controller handed them over to the Cincinnati TRACON, the facility responsible for controlling aircraft bound for Cincinnati International Airport, located just across the Ohio River from its eponymous city, in Boone County, Kentucky. The TRACON controller in turn attempted to identify flight 797 on radar, but initially mixed it up with another plane, not realizing that the Air Canada DC-9 had lost its transponder and was not showing up normally. By 19:12, however, he had managed to correct the misunderstanding by ordering flight 797 to make a turn, allowing him to identify its target. At that point the controller understood that flight 797 was now, and always had been, too close to the airport for a straight-in landing to the north on runway 36, as he had envisioned. In fact, the plane was only eight nautical miles from the runway threshold and still at 8,000 feet — there was no way to safely descend to the runway in time. Instead, he was forced to send flight 797 farther to the east and then back again to line it up for runway 27 Left. By 19:14, flight 797 was descending toward 3,000 feet and was cleared for approach.

Diagram of flight 797’s landing and the firefighting response. (Macarthur Job’s “Air Disaster: Volume 2”)

Although the airport was nearly in sight, the situation faced by the crew was deteriorating rapidly. As the plane descended, the emergency AC bus lost its connection with the battery, and all their instruments failed again. This time there was no way to bring them back, and Captain Cameron was forced to peer through the dense smoke in order to read the tiny standby instruments on the center console, which consisted of nothing more than an attitude indicator, vertical speed indicator, airspeed indicator, and magnetic compass. Captain Cameron also noticed that the controls were becoming progressively heavier as the DC-9’s hydraulic system began to lose power.

Shortly before 19:15, flight 797 reached 3,000 feet, but the pilots found that at this altitude they were still in clouds. Captain Cameron pressed onward to 2,000 feet, where they finally emerged into visual conditions — although the conditions inside the plane made visibility a challenge regardless.

Becoming worried that the smoke would prevent them from executing a safe landing, First Officer Ouimet tried to think of a solution. Both pilots initially tried opening their sliding cockpit windows, but this made too much noise. Instead, Ouimet eventually settled on turning off the air conditioning packs, which were still receiving power from the emergency DC bus. It would later be noted that while Ouimet thought the air conditioning system was feeding more smoke into the cabin, the opposite was actually true, and turning the packs off probably increased the rate of smoke accumulation inside the plane.

With fire trucks in position, the controller now asked the pilots for souls on board and fuel, but they replied that they didn’t have time. Both pilots were fully engaged in a Herculean effort to line up for the runway with inoperative instruments and heavy, sluggish flight controls. And yet, somehow, they did it; from just a few miles out, they spotted the runway and were cleared to land. In the control tower, the local controller could see the plane coming, its normal appearance belying the terror unfolding inside. Indeed, at 19:20, as the controllers looked on, Air Canada flight 797 touched down normally on runway 27L, fire trucks hurrying along behind it. Captain Cameron applied maximum braking, and while the anti-skid system was not working, causing all the tires to blow out, he was able to bring the plane safely to a halt. In the cabin, relief was palpable — the worst was surely over. Little did they know that the horror had only just begun.

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A passing pilot snapped this picture of Air Canada flight 797 burning on the runway. (Capt. Grieder)

As soon as the plane came to a stop, a frantic evacuation began. Flight attendants opened both forward exits, while passengers opened three of the four overwing exits, and people began to stream out of the plane. Those who managed to escape slid down the slides and into the waiting arms of the firefighters, who were already spraying down the exterior of the plane with foam. But inside the cabin, the conditions were beyond dire. The smoke was so thick that passengers couldn’t see their hands in front of their faces — the only way to see anything, or to breathe, was to drop down to the floor and crawl. The exits were invisible, hidden behind a pall of black smoke as passengers struggled to find them. One woman recalled spotting an overwing exit when she saw a faint light through the smoke; another located an exit only when she felt a draft across the back of her knees. Flight attendants tried to call for the passengers to follow them, but with so much smoke it was impossible to yell, and hardly anyone heard them. Sergio Benetti helped seven passengers escape through the L1 door, but after that, no more came. Laura Kayama was already outside helping passengers on the ground, and Judie Davidson at the L2 door had gone to assist her after no passengers appeared at her exit. Seemingly alone in the cabin, Benetti tried to move aft to see if anyone was left, but he was beaten back by the hellish conditions, so he too exited the airplane.

Flight 797 burns on the runway minutes after landing. (WLWT 5 News)

At the overwing exits, however, people were still streaming out onto the wings, coughing uncontrollably, their faces stained with soot. Firefighters began devising a plan to enter through the aft left overwing exit, hoping to get in between the passengers and the fire, but when they attempted to enter the plane, they were forced back by intense smoke and heat.

In the cockpit, the pilots finished shutting down the engines and attempted to exit through the galley, but couldn’t get past the doorway. Thinking quickly, First Officer Ouimet exited through the open cockpit window, dropping to the ground using the built-in escape rope. Behind him, Captain Cameron could be seen sitting in his seat, struggling to move, on the verge of losing consciousness. At Ouimet’s exclamation, firefighters sprayed foam through the open window, and Cameron was shocked into wakefulness. Without hesitation he got up and squeezed out the window, landing heavily on the asphalt before being pulled to safety.

It was then, just 90 seconds after the plane came to a stop, that the entire passenger cabin exploded in flame. An unstoppable wall of fire swept forward from the back of the plane, consuming everything in its path, painting every window in brilliant orange. Firefighters tried to fight it, but there was nothing they could do. Captain Cameron, who jumped from the window just seconds before the explosion, would be the last to leave the plane alive.

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A map of the seating locations of the survivors, along with the locations where the bodies were found, and the damage to the airplane. (Matthew Tesch for Macarthur Job’s “Air Disaster: Volume 2,” with reference to NTSB materials)

As firefighters worked to bring the blaze under control, the flight attendants lined up the passengers and began to count. Their grim tally would stop at just 18. Although all five crewmembers had survived, 23 of the 41 passengers did not escape the plane, succumbing to the smoke, toxic gases, and intense heat. For the pilots and flight attendants alike, it was a devastating blow — despite their successful effort to get the plane on the ground, half of those on board had died anyway.

In the end, it took 56 minutes for the firefighters to extinguish the fire, by which time the DC-9 sat gutted on the runway. Its roof had burned through, and little remained of the cabin above the window line, but lower down, seat cushions and carpets still sat unburnt. And in the blackened seats and aisles lay the bodies of the 23 people who never made it out. Some of the bodies were found in the forward aisle where they had fallen, whereas others evidently never left their seats — perhaps they were incapacitated even before the landing, or they may have died waiting for an evacuation order which they couldn’t hear; no one could be sure. Two bodies, however, were found at rows 14 and 16, behind the overwing exits in row 12, where nobody had been seated. It was obvious what had happened to them: after moving aft toward the exits, they failed to find them in the pitch darkness, overshot the exit rows, and succumbed to the toxic fumes.

Indeed, although many of the bodies were badly burnt, it was the smoke which killed them. Blood tests showed that several of the victims’ bodies contained lethal quantities of carbon monoxide, and all of them contained lethal concentrations of cyanide. In all likelihood, most of them were already dead by the time the flash fire occurred.

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Fire damage in the aft lavatory. (NTSB)

The following day, Canadians were stunned to learn that not only had 23 people died on an Air Canada plane, but that one of them was Stan Rogers. Survivors recalled seeing the big, bearded musician before the evacuation started, but he never emerged from the smoke-filled cabin, perishing alongside so many others.

As Canada mourned the tragic loss of life and musical talent, investigators from the National Transportation Safety Board began the dispassionate task of determining how the fire started and why so many people died.

By examining the wreckage of the aft lavatory, they were able to discern a certain pattern in the spread of the fire. As far as they could tell, the fire started in or just outside the lower left aft corner of the lavatory, hidden behind the amenities unit, and propagated outward and upward from there. Shortly after its ignition, the fire burst an adjacent air supply line, causing the blaze to accelerate until it penetrated the lavatory wall, venting smoke into the hidden spaces between the cabin interior and the fuselage skin. Some of this smoke began to seep into the lavatory through seams in its paneling, where it eventually made its way into the cabin and was detected by passengers.

Initially, however, most of the smoke and hot gases were jettisoned overboard via the lavatory vent line, which led out of the plane via a servicing panel in the tail. However, the aluminum vent line eventually melted, causing the hot gases to pour into the area underneath the lavatory floor.

At about 19:03, the fire melted the check valve at the entrance to the toilet flush and fill pipe, which also led outside the plane, creating another exit path for the smoke. Occurring at around the time that flight attendant Sergio Benetti opened the door and discharged the fire extinguisher, this combination of events caused the concentration of smoke in the cabin to decrease. This explained the “clearing” observed by many crewmembers and passengers between approximately 19:04 and 19:07.

During this same period, the hot gases venting into the floor melted the feeder cables from the left and right electrical generators. This damage likely caused the later series of electrical failures which occurred between 19:05 and 19:08. Around this time, the fire also destroyed the power supply to both flight recorders, which stopped simultaneously at 19:07:41, while the plane was still at 33,000 feet.

Firefighters work to extinguish the smoldering DC-9. (Bureau of Aircraft Accidents Archives)

From there, the fire continued to spread, using the gap between the lavatory wall and the fuselage skin as a flue. This directed hot gases upward, where they left scorch marks in the shape of the lavatory walls on the upper skin of the tail, probably while the plane was still in flight. This upward spread also caused smoke and toxic gases to accumulate inside the ceiling, whence they seeped into the passenger cabin during the descent. However, in contrast to some other famous in-flight fires, the blaze did not become particularly large prior to landing. It was more of a slow, smoldering fire — in fact, it is thought to have been burning for as long as 42 minutes by the time the plane stopped on the runway, and yet it never grew large enough to produce visible flames inside or outside the plane. The first time anyone saw any actual fire was when the cabin suddenly burst into flames, 90 seconds after landing.

Although the explosion aboard flight 797 is sometimes described as a “flashover,” this term does not accurately describe what happened. A flashover occurs when combustible materials, such as seats and carpets, are heated above their ignition temperature, and then instantly combust when an oxygen source is introduced. In contrast, what happened aboard the DC-9 was more likely a “flash fire.” While burning inside confined spaces within the structure of the airplane, the limited oxygen supply caused some fuels to partially rather than fully combust, releasing highly flammable gases which accumulated near the ceiling. When the doors were opened after landing, an unlimited oxygen supply was introduced, and after 90 seconds, sufficient oxygen was present to allow a heat source — in this case, probably the fire itself — to ignite all the flammable gases at once. The resulting “flash fire” had as much in common with an explosion as it did with a flashover. Either way, anyone still in the cabin who had not yet died from carbon monoxide or cyanide poisoning would have been killed within about 20 seconds.

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The front page of the Cincinnati Enquirer the day after the accident. (newspapers.com)

The next big question was what started the fire. In this area, the NTSB examined three main ignition sources: an overheating toilet motor, a cigarette, or electrical arcing.

Because the toilet motor was the first system to show any indication of failure, there was considerable suspicion that it was somehow involved. The NTSB conducted several tests in which they caused a flush motor to seize, then measured the temperatures both inside and outside the motor housing. Although the housing reached a temperature of 207˚C, and the rotor inside reached 325˚C, neither caught fire. A later test inside a mock lavatory reached even higher temperatures, but the motor did not ignite any of the surrounding material. Even after heating the motor housing to over 425˚C by electrical induction, the investigators couldn’t get a fire to start. Furthermore, these tests left distinctive scorch marks on the motor which were not found on the toilet motor recovered from flight 797, and none of the tests tripped the circuit breakers.

As a result of these tests, the NTSB ruled out the toilet flush motor as a possible cause of the fire. Most likely, the circuit breakers for the flush motor popped when the fire damaged the insulation around the motor’s power supply, causing the wires to short circuit.

Evidence also cast doubt on the cigarette theory. The trash bin was equipped with a fire extinguisher, which had activated, and some of the paper trash inside was found scorched, but not burned. It was also hard to imagine how a fire could have migrated out of the trash bin, across the vanity, and into the toilet, short-circuiting its motor, without producing enough smoke to be noticed in the cabin.

One other explanation was that if the trash bin was improperly mounted, a cigarette could have slipped through a gap and into the interior of the amenities unit, where it could roll through a small hole in the wall and end up in the corner of the unit near where the fire was believed to have started. Trash was found in this area on another DC-9, indicating that objects could work their way down there, and crumpled paper towels could have provided fuel. In the end, the NTSB couldn’t rule out this scenario, although the probability of a lit cigarette landing just right was rather low.

Two angles on the interior of the airplane after the accident. (Photos by NTSB, reprinted in Macarthur Job’s “Air Disaster: Volume 2”)

The other remaining theory was electrical arcing. Overall, the circumstantial evidence strongly pointed to this scenario, but physical evidence was lacking.

Most notably, the cockpit voice recorder captured the sound of electrical arcing eight separate times between 18:48, three minutes before the circuit breakers popped, and 19:00. These sounds were not audible to the crew, and were most likely induced directly into the CVR wiring by arcing in an adjacent wire run. Among the wires running near those for the CVR were the generator feeder cables, which passed underneath the lavatory floor.

The generator feeder cables, which transmit electricity from the electrical generators to the distribution buses, contain more than enough energy to start a fire. Furthermore, some evidence of arcing was found on recovered sections of the feeder cables, in an area where the insulation had been chafed due to contact with a floor beam underneath the lavatory. At first glance, this would seem to be the smoking gun, but there were several items of evidence which argued against this being the point of ignition. For one, the area where the arced wires were found, while heavily damaged, had mostly been affected by extreme heat rather than fire. Many of the wires were melted, but not burned. This suggested that these wires may have been damaged well after the fire started, when the lavatory vent line melted through, releasing hot gases into the underfloor area. The assumption that this damage occurred only as a result of the fire would also explain why no faults with the electrical distribution system occurred until 19:05, nearly 15 minutes after the toilet circuit breakers popped.

Additional evidence against this point of ignition was that the fuel source and spread path from the area of arcing to the bottom left corner of the lavatory could not be established. Furthermore, although there had been many faults with the plane’s electrical system leading up to the accident, these all concerned the auxiliary power unit, which notably was the one generator whose wiring was not involved in the suspected arcing.

C-FTLU sits on the apron prior to being moved to a hangar. (NTSB)

However, even if the generator feeder cables were not the source, that didn’t mean that electrical arcing didn’t cause the fire. In fact, the arcing sounds on the CVR still strongly suggested this. The plane’s extensive maintenance history, as well as the large number of wires near the lavatory which were spliced while repairing the aft pressure bulkhead, both pointed in this direction. But investigators didn’t find evidence of electrical arcing on any of the spliced wires which were recovered, and a large number had burned away entirely, preventing this scenario from being properly examined. In the end, the NTSB wrote that the cause of the fire could not be determined, but many of the individual investigators still strongly suspect that the fire started from a spliced wire which was destroyed in the accident.

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The plane as seen after it was towed to the hangar for examination. (NTSB)

In addition to the causes of the fire, the NTSB also sought to understand whether the crew acted properly during the emergency. This area of inquiry would prove to be highly controversial, and in an uncharacteristic lapse for the agency, there remains considerable doubt that all of the NTSB’s conclusions were justified.

The official report certainly was not a complete killjoy — in fact, it praised the pilots for “outstanding airmanship without which the airplane and everyone on board would certainly have perished.” Indeed, the pilots accomplished an impressive feat, landing a jet full of smoke without electrical power, primary instruments, or a working horizontal stabilizer. But the NTSB nevertheless felt that they missed opportunities to get on the ground sooner than they actually did.

The first noteworthy opportunity was when the toilet flush motor circuit breakers popped. This event did not require any particular response from the pilots, but investigators felt that from a standpoint of passenger comfort, it would have been normal for Captain Cameron to send a flight attendant back to investigate the status of the lavatory. After all, if the toilet wasn’t working, the flight would eventually become rather uncomfortable. Had such an order been given, the smoke may well have been discovered several minutes sooner, but since this was a judgment call rather than a procedural requirement, investigators could not strictly fault him for it.

The report also noted that First Officer Ouimet’s decision to turn off the air conditioning packs several minutes before landing was not called for in any emergency procedures and may in fact have made the situation even worse. Experts estimated that it robbed the passengers of two full cycles of fresh air. However, the investigators accepted that Ouimet was not aware of the consequences, and that the logic he used to come to his decision, while erroneous, would have made sense to him at the time.

Another view of the burning airplane, with context. (Al Behrman)

The NTSB was considerably harsher about the time taken to evaluate the location and severity of the fire after it was discovered but prior to initiating the emergency descent at 19:08 or 19:09. In his testimony before the board, Captain Cameron stated that he believed he was dealing with a trash bin fire or toilet motor fire right up until 19:07, when system failures escalated to the point that these theories had to be discarded. On the other hand, flight attendant Sergio Benetti and First Officer Ouimet were aware that the location of the fire was actually unknown, and had been aware of this since around 19:03 at the latest. Benetti had even told Ouimet that he didn’t think the fire was in the trash bin. And yet, Captain Cameron continued to believe that the fire was in the bin for several more minutes, all while flight 797 remained at its cruising altitude. Clearly some kind of miscommunication had occurred.

In the NTSB’s opinion, an emergency descent should have been initiated at 19:04:07, when Ouimet returned to the cockpit and said “I can’t go back now, it’s too heavy, I think we’d better go down.” This statement indicated that the location of the fire was unknown and implied that it was not under control. The fact that it then took another five minutes to begin the descent was, in the investigators’ opinion, a serious problem.

In fact, an analysis showed that had the descent been initiated at 19:04:07, it might have been possible to land in Louisville, Kentucky between three and five minutes earlier than the flight’s actual landing in Cincinnati at 19:20, depending on whether the optimal descent profile was achieved. Those three to five minutes may well have meant the difference between life and death for some of the passengers. (Incidentally, the controller was cleared of any contribution to the delay, despite his initial misidentification of the airplane on radar, because flight 797 flew the shortest possible route to Cincinnati anyway.)

But instead of descending at 19:04, as the NTSB believed they should have, the pilots kept the plane at its cruising altitude while Ouimet went back to assess the fire a second time. This decision seemed to have been made because of statements to the effect that the smoke was clearing. The investigators believed that Ouimet need not have been sent back a second time, and that the comments about smoke clearing were misleading and distracting, since it had already been established that the fire was not in the trash bin and was not under control.

Officials examine C-FTLU in the hangar. (Clint Groves)

As a result of these factors, when the NTSB published its official report in 1984, it wrote that the probable causes were “a fire of undetermined origin, an underestimate of fire severity, and conflicting fire progress information provided to the captain.” Under contributing factors, they added that, “Contributing to the severity of the accident was the flight crew’s delayed decision to institute an emergency descent.”

This conclusion was devastating for the pilots, whose names and reputations were immediately dragged through the mud by the media. Although the media generally did not mention the NTSB’s praise of the pilots’ airmanship, it was also hardly their fault that the praise was buried in the middle of the report while the criticism was elevated to the probable cause. And to make matters worse, there were plenty of questions about the validity of the analysis on which this probable cause was based in the first place. Consequently, First Officer Ouimet submitted a formal letter of contestation, which was amplified by the Air Line Pilots Association, requesting that the probable cause be revised.

Although Ouimet pointed out a number of more minor mistakes in the NTSB’s account of events, such as who flipped the emergency power switch, his primary area of concern was the determination that the descent was unduly delayed. In his opinion, the NTSB failed to adequately weigh the significance of the statements which led Captain Cameron to believe that the fire was, in fact, under control.

Indeed, the transcript shows that immediately after Ouimet mentioned that he “couldn’t go back,” Cameron was told five separate times by three different people that the smoke was clearing and that he need not worry. The smoke did in fact clear at this point, albeit by coincidence, not because Sergio Benetti’s firefighting efforts were effective. But the statements clearly implied that the smoke was clearing because the fire extinguisher had been emptied into the lavatory. The NTSB called this “conflicting fire progress information,” but in Cameron’s mind, he certainly was not receiving conflicting information — he was being told without caveat that the situation was under control, and in fact everyone believed this to be the case until multiple system failures occurred.

Front page of ALPA’s petition to revise the probable cause. (NTSB)

There were a number of other points of contention regarding logical inconsistencies in the NTSB’s analysis, but the above matter was the most important. This fact was most clearly conveyed by ALPA, which requested that the line about the delayed decision to descend be changed to reflect the fact that this decision appeared justified based on the information Captain Cameron was getting. In the end, while the NTSB didn’t fix all of the errors pointed out by Ouimet, in 1986 it accepted ALPA’s petition and revised the probable cause. The relevant section now reads (changes in bold): “The probable causes were a fire of undetermined origin, an underestimate of fire severity, and misleading fire progress information provided to the captain. The time taken to evaluate the nature of the fire and to decide to initiate an emergency descent contributed to the severity of the accident.”

Obviously, for the flight crew this didn’t go far enough. But at the end of the day, it was what they were going to get.

Factual errors aside, the debate over when the crew should have made the decision to descend was very much a product of its time. To a modern reader, accustomed to an environment in which the mere utterance of the word “fire” is enough to send any pilot scrambling for the nearest airport, the NTSB’s judgment makes some sense. At the time, however, it was gratingly out of touch with the reality experienced by most flight crews. In 1983, there was no universal rule which called for an immediate emergency descent in the event of fire, as there is today. Procedures in fact placed quite a lot of weight on determining the source and severity of the fire before making such a decision, which is a necessary piece of background information when understanding the actions of the crew of flight 797. These procedures were written in the belief that the vast majority of fires aboard airplanes would be caused by lit cigarettes being dumped in the trash, and that such a fire was not an emergency. Indeed, when people could smoke on airplanes, it was impractical to declare a full-blown emergency every time someone saw smoke in the cabin!

Another view of the firefighting efforts. (Bureau of AIrcraft Accidents Archives)

It would take other in-flight fires, such as Swissair 111, as well as the end of smoking on airplanes, before this mentality truly began to change. For that reason, it’s not possible to point to significant improvements in pilot training which occurred as a result of the tragedy aboard flight 797. But what the accident did do was introduce major changes in the field of passenger survival which are now familiar to everyone who flies.

The most basic problem was that Air Canada flight 797 was an eminently survivable accident, in which 23 people nevertheless lost their lives. In an ideal world, this number could have and should have been zero. But in the event, just getting to the exits was so difficult that fewer than half of the passengers managed to do it.

The NTSB had been trying to improve the ability to detect, combat, and escape smoke and fire in the cabin for many years, but the most pointed recommendations to this effect were made in 1973, after a Varig Boeing 707 crash-landed short of Paris due to a fire in the aft lavatory. 124 of the 134 people on board died after inhaling toxic smoke; only the crew and a single passenger got out alive. As a result of this disaster, the NTSB recommended that all airliners be equipped with lavatory smoke detectors in order to provide more timely warnings to the crew. However, at that time smoke detector technology was considered insufficiently reliable, and this recommendation was rejected.

Ten years later, however, things had changed. Smoke detectors were now fully mainstream, and some airlines were already adopting them voluntarily. Following Air Canada flight 797, the NTSB again recommended that they be made mandatory, and this time the Federal Aviation Administration unhesitatingly agreed. As a direct result of the accident, lavatory smoke detectors have been mandatory on all US-made and US-registered airliners since 1986.

A sign warns of a lavatory smoke detectors and the consequences of tampering with it. These signs, ubiquitous today, would not have been seen before 1986. (Mark’n Markus on Flickr)

The changes did not end there. Again as a result of NTSB recommendations stemming from flight 797, in 1987 the FAA mandated that all airliners have automatic fire extinguishers in their lavatory trash bins, and that portable fire extinguishers be upgraded from CO2 to halon.

In the field of passenger survival, the NTSB recommended that track lighting be installed in the cabin floor to help guide passengers to the exits in conditions of darkness or smoke. The FAA made this feature mandatory in 1986, and it is now mentioned in every passenger safety briefing. That same year, new standards for fire retardant cabin materials were introduced. Then in 1987, the FAA mandated that flight attendants have access to full face breathing equipment and smoke goggles to help them fight fires, and that operating manuals include effective procedures for the removal of smoke from an aircraft in flight, even if the fire is still burning. Finally, the accident contributed to the standardization of special briefings for exit row passengers, something which the cabin crew did on flight 797, but was not yet mandatory.

Taken together, these changes have both decreased the frequency of serious cabin fires and improved survival when they do occur. Today, when a fire ignites on board an aircraft, as a general rule, if the plane can be safely landed or stopped on the runway, everyone survives.

◊◊◊

A closer view of C-FTLU’s soot-stained windows. (Bureau of Aircraft Accidents Archives)

Air Canada flight 797 was a landmark accident which resulted in tangible improvements to safety, ensuring that those who died did not do so in vain. But this hardly dulls the pain of knowing that they very nearly lived, that the pilots landed the plane, that the doors were opened, that the firefighters were on the scene before the plane even stopped, and yet so many people still lost their lives. While it is hard to see what anyone could have done differently, this doesn’t shake the nagging sense that their deaths were senseless or preventable.

Whenever people die in such a manner, there is also a profound sense that some once-manifest future has been lost, and this effect is rarely so widely visible as when an accident takes the life of a public figure. For that reason, no discussion of flight 797 is complete without circling back to Stan Rogers. He has now been dead for considerably longer than he was alive, and yet his music continues to hold a special place in the hearts of millions of Canadians. His songs spoke to a particularly Canadian spirit in a way that no one has managed to replicate since. And yet there is a belief that perhaps his greatest songs were never written and never will be. In an effort to derive some meaning from this loss, people often say that Rogers died saving other passengers from the fire. But no one who was there remembered seeing him do this, nor are most of the stories remotely plausible. Stan Rogers may have been dear to a nation, but his death played out no differently than those of the 22 others who died alongside him.

Stan Rogers is commemorated on a Canadian postage stamp. (stanrogers.net)

Let us conclude, then with a few lines from “Northwest Passage,” Stan Rogers’ most famous song, which is sometimes called Canada’s unofficial second anthem.

“Oh, for just one time

I would take the Northwest Passage

To find the hand of Franklin reaching

For the Beaufort sea…

Tracing one warm line

Through a land so wide and savage

And make a Northwest Passage

To the sea.

And through the night, behind the wheel

The mileage clicking west

I think upon Mackenzie,

David Thompson and the rest

Who cracked the mountain ramparts

And did show a path for me

To race the roaring Fraser to the sea…”

In the song, Rogers contemplates the fate of explorers such as Franklin, who failed in their search for the Northwest Passage, only for he, centuries later, to follow their arduous path across Canada from the comfort of his car. In aviation safety, then, it is clear only now that Stan Rogers and the other victims of flight 797 were more like the explorers than those who followed them — their deaths may have been needless, but the lessons of their last journey nevertheless “cracked the mountain ramparts” and smoothed the passage for the rest of us.

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Admiral Cloudberg

Analyzer of plane crashes. Contact me via @Admiral_Cloudberg on Reddit, @KyraCloudy on Twitter, or by email at kyracloudy97@gmail.com.