What happened during the Delta Flight 4819 crash landing at Toronto's Pearson Airport?

During the crash landing, passenger John Nelson experienced terrifying moments as the plane went down. He described seeing a giant firewall along the side of the aircraft and feeling intense heat through the glass. The plane began moving sideways and tumbling, though he wasn't certain how many times it rolled. Ultimately, the aircraft flipped completely and came to rest upside down, leaving all 80 passengers and crew suspended in their seatbelts. Despite the severity of the crash, which involved the landing gear failing and the right wing striking the ground, everyone survived thanks to the heroic actions of flight crew and first responders, though 21 people were injured.