The alert system of the plane that crashed at Toronto’s Pearson airport last month indicated a rapid descent rate less than three seconds before touchdown, a preliminary report into the crash has found.
The Transportation Safety Board of Canada (TSB) issued its report on March 20 as part of its ongoing investigation into the Feb. 17 crash landing during which the Delta Air Lines plane arriving from Minneapolis caught fire before overturning on the runway.
All 76 passengers and four crew members survived, but 21 individuals were injured and taken to hospital. All were released by Feb. 21.
The TSB report indicates the ground proximity warning system was triggered 2.6 seconds before the aircraft touched down, “indicating a high rate of descent.” At that time, the plane showed an airspeed of 136 knots—which is roughly 250 kilometres per hour—and a rate of descent of 1,100 feet per minute.
At 1.6 seconds before touchdown, the airspeed remained the same and the rate of descent had decreased to 1,072 feet per minute, the report said. At less than one second before touchdown, the plane’s airspeed dropped slightly to 134 knots and the rate of descent was recorded at 1,110 feet per minute.
Transport Canada’s guidelines set maximum sink rate at 1,000 feet per minute for commercial flights.
When the plane touched down, its landing gear folded up, and the wing came loose from the fuselage, resulting in a release of jet fuel that ignited, the preliminary report said. As the aircraft slid along the runway, it rolled to the right and overturned.
A large section of the tail, including most of the vertical stabilizer and the entire horizontal stabilizer, separated during the roll, the report said. Stabilizer wings play a crucial role in ensuring the aircraft’s stability, allowing it to maintain a straight flight path.
Once the plane flipped, passengers were left dangling upside until they removed their seatbelts.
“The flight crew had to exit through the emergency hatch located on the ceiling of the cockpit,” lead investigator Ken Webster said in a video that accompanied the report. “After everyone on board evacuated, the emergency response personnel entered the fuselage, after which an explosion occurred outside the aircraft in the area of the left wing route. The cause of this explosion has yet to be determined.”
A visual inspection of the flight control components revealed no obvious pre-existing defects or issues, Webster said. The preliminary analysis of the flight data recorder showed an absence of any caution or warning messages concerning the flight controls, he added.
The investigation into the crash will continue with a focus on areas such as the metallurgical analysis of the wing structure, landing procedures, pilot training, cabin obstructions and impediments, and the process of passenger evacuation, Webster said.
“The investigation into this accident will take some time, as many questions remain unanswered,” he noted. “The TSB will continue to work toward determining the full sequence of events that led to the accident.”
The investigation into the crash of Delta flight 4819, operated by its subsidiary Endeavor Air, is being led by the Transportation Safety Board of Canada and is supported by the U.S. Federal Aviation Administration (FAA), the U.S. National Transportation Safety Board, Delta’s incident response team, and Mitsubishi, the manufacturer of the CRJ900 aircraft, which was originally produced by Bombardier.
Delta has made a US$30,000 compensation offer to the passengers who were involved in the crash, calling it a “no strings attached” offer.
At least two lawsuits have been launched in the United States, and a law firm in Canada has reported that it has been hired by several passengers.
