Aviation experts say a list of actions and circumstances aligned to ensure that nobody died when Delta Airlines flight 4819 crash-landed and slid down the runway at Toronto Pearson Airport last week, before coming to rest upside-down and facing the opposite way amid smoke and flames.
The Transportation Safety Board of Canada (TSB) is looking for the cause, using data from black boxes and interviews and examining the wreckage at an airport hangar. The agency’s U.S. counterpart, the National Transportation Safety Board (NTSB), is aiding the probe, along with Mitsubishi, which purchased the CRJ class from Bombardier in 2020.
To learn how a plane can crash at about 200 kilometres an hour and 80 people walk away, The Globe and Mail interviewed aviation-industry experts, including former crash investigators from the TSB and NTSB.
Hassan Shahidi, president of the Flight Safety Foundation, a non-profit group based in Virginia, says the answer is multilayered.
“When you look at the totality of this accident, the design, the manufacturing, the engineering, the first responders and as well as the cabin crew, all of these things worked together to have a good outcome to a terrible accident,” Mr. Shahidi said.
The slide
David McNair, who spent 31 years as an investigator at the TSB, says the aircraft’s slide and lack of a violent stop preserved the fuselage and prevented people from dying, either from the collision with the tarmac or any secondary impacts within the plane.
He points to the belly-landing of a Jeju Air Boeing 737 in South Korea in December. The plane slid off the runway and slammed into a concrete wall, an impact officials say was responsible for killing most of the 179 people who died.
In the case of Delta flight 4819, there was no sudden stop, and the body remained intact. “It’s the dynamics of the accident that determine the forces on the fuselage and its survivability,” Mr. McNair said.
Investigators examine the wreckage of Delta Airlines flight 4819 a day after it crashed upon landing at Toronto Pearson International Airport. At least 18 people were injured when the plane flipped upside-down. There were no fatalities.GEOFF ROBINS/AFP/GETTY IMAGES
The seats and belts
Most modern passenger planes are fitted with seats that can withstand forces of up to 16 times gravity. These 16G seats are mandatory in most passenger planes built in the past two decades.
Use of the seats, rigorously tested and fastened according to specifications, would have prevented 51 deaths and 54 injuries in survivable plane crashes worldwide between 1984 and 1998, the U.S. Department of Transportation found in a 2000 study.
The CRJ900, built in 2008, presumably had its seats upgraded at some point.
Mr. Shahidi said the seat design and the engineering that bolts them to the aircraft, coupled with the use of seat belts, saved lives. The seats remained stable in the crash and subsequent inversion, able to hold the weight of the travellers upside-down.
“If they weren’t wearing their seat belts, they would have surely been thrown around, with severe injuries, possibly fatalities,” Mr. Shahidi said. “Those seat belts saved lives that day.”
Flight attendants
A video shot by a passenger on the plane shows a flight attendant and passengers helping people through the upside-down door. “Drop everything! Drop it!” the flight attendant orders the passengers as she helps them onto the tarmac from the flipped fuselage, which was leaking jet fuel and smouldering.
Deborah Flint, chief executive officer of Pearson’s operator, the Greater Toronto Airports Authority, said the flight crew saved lives. “The crew of Delta flight 4819 heroically led passengers to safety, evacuating a jet that had overturned on the runway on landing that was amidst smoke and fire.”
The two attendants on board have made no public statements, and their U.S. union did not respond to interview requests.
Jeff Guzzetti, a former NTSB investigator, said the crew was doing as they were trained, taking charge and getting most people to safety even before first responders arrived. “It’s incredible,” he said. “Their mission is not to give out drinks and peanuts. Their mission is to react in the event of an incident or an accident.”
Videos posted on social media show passengers evacuating the Delta plane that crashed and flipped at Toronto's Pearson airport.
THE CANADIAN PRESS
The landing gear
A widely seen video of the crash shows the right landing gear touching the runway first and immediately collapsing. The plane pitches to the right, smashing and tearing off the right wing in an explosion of flame. As disastrous as this looks, this sequence is in accordance with rules governing design, Mr. Guzzetti said.
Landing gear is built to absorb the energy of a hard touchdown by collapsing. And U.S. Federal Aviation Administration regulations say the gear must be built so that a failure does not rupture the fuel tanks in the wing right above it, creating a fire hazard.
When the CRJ900 shed its wing, which contains a main fuel tank, it left behind a major source of fire, he said. The CRJ900 can hold almost 9,000 kilograms of highly flammable jet fuel, although the load would have been much lighter after a 90-minute flight from Minnesota.
Had the wing been attached and in flames while people were trying to leave the plane, it would have been a different outcome, said Mr. McNair, the former TSB investigator.
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