The alert system on a Delta Air Lines jet that flipped upside-down and burst into flames as it tried to land in Toronto last month indicated a high rate of descent less than three seconds before touchdown, a preliminary report said on Thursday.
The Transport Safety Board of Canada, which issued the report, continues to investigate the February 17 crash-landing after which 21 people were admitted to hospital.
All 76 passengers and four crew members survived when the Delta plane arriving from Minneapolis burst into flames after flipping over and skidding on the tarmac.
The TSB report says that when the plane’s ground proximity warning system sounded 2.6 seconds before touchdown, the air speed was 136 knots, or about 250kph. It says the plane’s landing gear folded into the retracted position at touchdown and the wing detached from the fuselage, releasing a cloud of jet fuel, which caught fire as the plane skidded along the runway.
The fuselage rolled upside-down and a large portion of the tail came off in the process, the report says.
“Accidents and incidents rarely stem from a single cause,” TSB chair Yoan Marier said in a video statement on Thursday. “They’re often the result of multiple complex, interconnected factors, many extending beyond the aircraft and its operation to wider systemic issues.”
The crew and passengers started trying to leave when the plane came to a stop, the report says, adding that some of the passengers were injured when they unbuckled their seat belts and fell to the ceiling. The TSB said it is not aware of any issues with the seat belts or seats during the incident.
The cockpit door was jammed shut, forcing pilots to escape through the emergency hatch on the ceiling of the cockpit after everyone else was out, the report says.
Emergency response personnel then went into the fuselage, and there was an explosion outside the plane near the left wing root shortly after, the TSB says. The cause of the explosion has not yet been determined.
So far, the investigation has found no pre-existing problems with the flight controls, although some parts were damaged in the crash, the board said.
The safety board says its continuing investigation is focusing on several key areas, including metallurgical examination of the wing structure, landing techniques, pilot training and the passenger evacuation process.
All of those who were admitted to hospital were released within days of the crash. At least two lawsuits have been filed in the US, and a law firm in Canada has said that it has been retained by several passengers.
Delta declined to comment on the preliminary report.