Air Canada Flight 797

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Air Canada Flight 797 was a scheduled trans-border flight that flew from Dallas/Fort Worth International Airport to Montréal-Dorval International Airport, with an intermediate stop at Toronto Pearson International Airport. On 2 June 1983, the McDonnell Douglas DC-9-32 operating the service developed an in-flight fire behind the lavatory that spread between the outer skin and the inner decor panels, filling the plane with toxic smoke. The spreading fire also burned through crucial electrical cables that knocked out most of the instrumentation in the cockpit, forcing the plane to divert to Cincinnati/Northern Kentucky International Airport. Ninety seconds after the plane landed and the doors were opened, the heat of the fire and fresh oxygen from the open exit doors created flashover conditions, and the plane's interior immediately became engulfed in flames, killing 23 passengers who had yet to evacuate the aircraft. Blood tests showed some of the passengers had inhaled lethal amounts of toxins from the in-flight fire, likely meaning they were already dead in their seats before the plane touched down.

As a result of this accident, aviation regulations around the world were changed to make aircraft safer, with new requirements to install smoke detectors in lavatories, strip lights marking paths to exit doors, increased firefighting training and equipment for crew, and regular instruction of passengers seated in overwing exits to assist in an emergency evacuation.

At the time of the accident, Air Canada had 41 other DC-9s in its fleet.

Video Air Canada Flight 797

Details

At 16:20 CDT (21:20 UTC) on 2 June 1983, the Air Canada aircraft, registered C-FTLU, took off from Dallas-Fort Worth International Airport; it was to make a stop at Toronto International Airport, ultimately bound for Dorval Airport in Dorval, Quebec (Montreal).

Donald Cameron, 51, was the captain and Claude Ouimet, 34, served as first officer. Both were experienced pilots - Cameron had accrued approximately 13,000 flight hours and Ouimet had 5,650 hours. While flying over Louisville, Kentucky, an in-flight fire started in or around the rear lavatory of the aircraft. The pilots heard a popping sound around 18:51 EDT (22:51 UTC), during dinner service, and discovered that the lavatory's circuit breakers had tripped. It was not uncommon, however, for a plane's lavatory circuits to pop occasionally, precipitated by the large number of passengers using the toilet after eating, so Cameron waited around eight minutes to give the tripped circuits time to cool down before attempting to reactivate them at 18:59.

A strong, noxious odour coming from the rear of the plane was first reported to the cabin crew around 19:00. Flight attendant Judi Davidson, 33, traced the odour to the lavatory. She attempted to look into the lavatory but was forced back by thick grey smoke rapidly filling the small room; she then ordered the third ranking crew member to find Sergio Benetti, 37, the chief cabin crew officer, and ask him to investigate. As Benetti sprayed the interior of the affected lavatory with a CO₂ extinguisher, Davidson reported the fire to the captain while 28-year-old flight attendant Laura Kayama began urging the passengers on the sparsely-populated flight to come away from the front and rear of the plane and sit close together near the over-wing exits. At no time did any of the cabin crew mention to either Cameron or Ouimet that they had not yet seen flames. Benetti, the one person who had managed to get a good look at the scene, had not reported seeing anything resembling the traditional causes of airline fires in pre-smoking-ban days: flames from a trash bin fire or the paper towel dispenser, both of which were commonly set ablaze by passengers smoking in the lavatories on long flights. First officer Ouimet went to investigate at 19:03, but was driven back by the thick smoke. At 19:04, Benetti reported that he thought the fire was probably out because he had completely doused the lavatory with fire retardant.

Just three minutes later, however, at 19:07, passengers reported smelling smoke in the cabin again. Two minutes after that the "master breaker" alarm went off in the cockpit, and electrical systems throughout the plane began to fail, including power for the elevator trim system. This made controlling the plane's descent extremely difficult and required great physical exertion from the pilot and first officer. The PA system also failed, leaving the flight attendants unable to communicate efficiently with the passengers; nevertheless, attendants were able to instruct passengers sitting in the exit rows on how to open the doors, a practice that was not standard on commercial airline flights at the time.

At 19:20, Cameron and Ouimet made an extremely difficult emergency landing at the Cincinnati/Northern Kentucky International Airport, located in Boone County, Kentucky, across the Ohio River from Cincinnati, Ohio. During the evacuation, the overwing aircraft doors were opened, causing an influx of air that fuelled the fire. Ouimet escaped through the co-pilot's emergency window shortly after the plane landed, but Cameron, who was exhausted from trying to keep the plane under control, was unable to move. Firefighters doused Cameron in firefighting foam through Ouimet's window, shocking him back to consciousness; Cameron was then able to open the pilot's emergency escape window and drop to the ground, where he was dragged to safety by Ouimet. Cameron was the last person to make it out of the plane alive. Less than 90 seconds after touchdown, the interior of the plane flashed over and ignited, killing 23 of the 41 passengers. The passengers trapped inside the plane died from smoke inhalation and burns from the flash fire. Dianne Fadley, a survivor, said that "it was almost like anybody who got out had nothing wrong"; of the eighteen surviving passengers, three received serious injuries, thirteen received minor injuries, and two were uninjured, while none of the five crew members sustained any injuries. "You made it and you were completely fine," Fadley concluded, "or you didn't make it."

Twenty-one Canadians and two Americans died. Many of the bodies were burned beyond recognition. Almost all of the victims were in the forward half of the aircraft between the wings and the cockpit. Some bodies were in the aisles, and some bodies were still in the seats. Two victims were in the back of the aircraft, even though the passengers were moved forward after the fire had been detected; the disoriented passengers moved beyond the overwing exits and succumbed. The blood samples from the bodies revealed high levels of cyanide, fluoride, and carbon monoxide, chemicals produced by the burning plane.

Maps Air Canada Flight 797

NTSB investigation

Because the accident occurred in the United States, it was investigated by the National Transportation Safety Board (NTSB). Though the fuselage was nearly destroyed by the intensity of the fire, the cockpit voice recorder (CVR) and flight data recorder (FDR) were still in good condition and produced vital data for the NTSB investigation. On the CVR, NTSB investigators heard eight sounds of electrical arcing--likely inaudible to the crew--beginning at 18:48 CDT. Three minutes later, at 18:51, the popping sounds that Cameron and Ouimet later identified as the left toilet circuit breaker tripping are audible on the CVR. Cameron attempted to reset the circuits twice in the next 60 seconds, but the CVR records the breakers immediately popping again after each reset attempt. Cameron attempted once more to reset the breakers at 18:59. The CVR records arcing sounds followed by the popping sound of the breakers continuing to trip again after each reset over the next 60 seconds. At 19:02, the CVR records flight attendant Judi Davidson entering the cockpit to deliver the first report of a possible fire in the lavatory. Though a number of wires in the lavatory section were later found with insulation stripped away, NTSB investigators were unable to determine whether this insulation damage was the cause of the fire or was caused by the fire.

This particular DC-9 had experienced a number of problems over the months leading up to the incident; 76 maintenance reports had been filed in the plane's logs in the previous year, and the CVR records Cameron telling Ouimet to "put [the tripping breakers] in the book there" when the breakers fail to respond to the first reset attempt at 18:52. Nearly four years earlier, on 17 September 1979, the plane, then serving as Air Canada Flight 680 (Boston, Massachusetts, to Yarmouth, Nova Scotia), had suffered an explosive decompression in the rear bulkhead that required rebuilding the tail section and replacing or splicing most of the wiring and hydraulic lines in the back of the plane; Cameron later noted that the Air Canada maintenance crew "did a heck of a job getting everything put back together" after the decompression incident. Investigators were unable to find signs of arcing in any of the wire splices from the repairs done four years earlier, though much of the wiring in the rear of the plane was severely damaged or destroyed by the fire itself.

Despite finding neither the specific wires that caused the short circuit (the usual cause of arcing sounds and the likely cause of the breaker trips) nor the origin point of the fire that later consumed the plane, investigators determined that a short circuit likely sparked and ignited surrounding materials (such as insulation blankets) that sustained and propagated a fire behind the wall of the lavatory, with the plane's outer skin serving as a conduit for smoke to seep in through the seams in the interior panels and collect near the apex of the cabin.

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Notable passengers

• Stan Rogers, Canadian folk singer, aged 33, was one of the deceased on the flight. Rogers is known for songs such as "Northwest Passage", "The Mary Ellen Carter" and "Barrett's Privateers". He was going home on Flight 797 after attending the Kerrville Folk Festival in Texas. He died in the fire of smoke inhalation.
• George Curtis Mathes Jr., aged 54, was another of the deceased on the flight. Mathes' father founded the electronics company that bears his name, and the younger Mathes was CEO of Curtis Mathes and Curtis Mathes Centers at the time of the incident. He had recently made large acquisitions in Canada and was travelling to finalize his corporate plans for a venture.

• Toronto multi-millionaire Glen W. Davis, then aged 42, survived the crash. Davis, owner of a trucking firm and a senior executive for other firms, claimed that surviving the crash led him to focus his life on philanthropy, revealed after his death in 2007 to have been more than $40 million in charitable donations. Twenty-four years later, on May 18, 2007, Davis was murdered in Toronto by his godson, wanting to hide his own financial wrongdoing while hoping to stop Davis' philanthropic disposal of his potential inheritance.

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Aftermath

Air Canada has not suffered another fatal accident since 1983.

Safety recommendations

As a result of this accident and other incidents of in-flight fires on passenger aircraft, the NTSB issued several recommendations to the Federal Aviation Administration (FAA), including:

• Safety Recommendation A-83-70, which asked the FAA to expedite actions to require smoke detectors in lavatories;
• Safety Recommendation A-83-71, which asked the FAA to require the installation of automatic fire extinguishers adjacent to and in lavatory waste receptacles;
• Strong recommendation that all US-based air carriers review their fire training and evaluation procedures; procedures were to be shortened and focused on taking "aggressive actions" to determine the source and severity of suspected cabin fires while finding the shortest and safest possible emergency descents, including landing or ditching;
• Strong suggestion that passenger instruction in how to open emergency exits become standard practice within the airline industry.
• Strong recommendation for expedited FAA rule changes mandating that all US-based air carriers install (or improve existing) in-cabin fire safety enhancements, including (but not limited to):
  • Fire-blocking seat materials to limit both the spread of fire and the generation of toxic chemicals through ignition;
  • Emergency track lighting at or near the floor, strong enough to cut through heavy fuel fire smoke;
  • Raised markings on overhead bins indicating the location of exit rows to aid passengers in locating these rows in case of passenger visual impairment (either pre-existing or caused by emergency conditions);
  • Hand-held fire extinguishers using advanced technology extinguishing agents such as Halon.

Criticism and controversy

Newspapers and other media criticized the actions taken by the crew and said that the pilots took too long to initiate an emergency descent; the initial NTSB report was especially critical of Cameron for not asking about the exact nature of the fire and not immediately initiating emergency descent when the fire was first reported. Cameron admitted in a press conference following the issuance of the NTSB report that he assumed the problem was a garbage bin fire, a common cause of lavatory fires when smoking was still allowed on flights.

Pilots and airline personnel throughout the industry petitioned the NTSB to revise its report. First Officer Claude Ouimet sent the NTSB a detailed defence of the crew's actions, including the decision to land in Cincinnati instead of Standiford Field Airport in Louisville, Kentucky, the airport closest to where the crew first notified Air Traffic Control in Indianapolis, Indiana, that they needed to make an emergency landing. Ouimet stated that Louisville was too close to be able to descend from cruising altitude to an emergency landing safely, and even landing in Cincinnati was a questionable proposition given Cameron's difficulties in controlling the plane. After reviewing Ouimet's missive and re-evaluating the available data, the NTSB issued a revised version of the report which included Ouimet's explanation of the landing decision, though the report was still critical of Cameron's decision not to inquire about the fire itself. "All I know was that I did the best I could," Cameron later said. "I'm very sorry the people that didn't get off, didn't get off, because we spent a lot of time and effort getting them there."

The crew of Flight 797 later received a number of citations from Canadian aviation organizations for their heroic actions in landing the plane safely. Cameron died in 2016, aged 84.

C-FTLU and N994Z

After this incident, Air Canada sold the right wing of this DC-9 aircraft to Ozark Air Lines to repair a damaged airplane. On December 20, 1983 Ozark Air Lines Flight 650, served by a DC-9 with tail number N994Z, had hit a snow plow in Sioux Falls, killing the snow plow operator and separating the right wing from the aircraft. A wing from C-FTLU was used to replace the one separated on N994Z after the incident. The aircraft was later sold to Republic Airlines, and acquired by Northwest Airlines after Republic merged with Northwest. As of 2012, N994Z was sold for scrap to Evergreen after being assigned to Delta Air Lines, which now owns Northwest Airlines.

Flight number

Air Canada continues to use flight number AC797 as of June 2017. It is used for a daily flight from Montreal to Los Angeles, then using an Airbus A320 aircraft.

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Dramatization

The Discovery Channel Canada / National Geographic TV series Mayday (also called Air Crash Investigation or Air Emergency) featured the accident in a 2007 episode titled Fire Fight which included interviews with survivors and accident investigators and a dramatic recreation of the flight.

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See also

• CAAC Flight 2311
• British Airtours Flight 28M
• China Airlines Flight 120
• Swissair Flight 111
• Asiana Airlines Flight 991
• ValuJet Flight 592

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References

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External links

• First NTSB accident report
• Second NTSB accident report (supersedes the first accident report)
• NTSB brief DCA83AA028
• Accident description at the Aviation Safety Network
• A photo of the burning airliner at Airliners.net

Source of the article : Wikipedia