A preliminary report into a plane crash at Toronto's Pearson airport last month says the aircraft's alert system issued a warning about the descent rate less than three seconds before touchdown.
The Transportation Safety Board of Canada released its report Thursday morning as it continues to investigate the Feb. 17 crash landing that sent 21 people to hospital, noting that it's too early to draw any conclusions.
All 76 passengers and four crew members survived when the Delta Air Lines plane arriving from Minneapolis burst into flames after flipping over and skidding on the tarmac.
"Accidents and incidents rarely stem from a single cause," TSB chair Yoan Marier said in a video statement Thursday.
"They're often the result of multiple complex, interconnected factors, many extending beyond the aircraft and its operation to wider systemic issues."
The TSB report says that when the plane's ground proximity warning system sounded 2.6 seconds before touchdown, the airspeed was 136 knots, or approximately 250 kilometres per hour. 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 slid along the runway.
The fuselage rolled upside down and a large portion of the tail came off in the process, the report says.
The crew and passengers started evacuating once the plane came to a stop, the report says, adding some of the passengers were injured when they unbuckled their seatbelts and fell to the ceiling.
The TSB says it's not aware of any issues with the seatbelts 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 afterward, 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, though some components were damaged in the crash, the board says.
"Preliminary data from the flight data recorder did not contain any caution or warning messages pertaining to the flight controls, but further analysis will be conducted as we continue some of the areas we will be focusing on," the agency says in a video.
The TSB says its ongoing 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 hospitalized were released within days of the crash.
Several lawsuits have been filed in the United States since the crash and a law firm in Canada has said that it's been retained by several passengers.
