Investigation Summary
The accident was rooted in a long-standing procedural disagreement between Captain Peter Hamilton and First Officer Donald Rowland regarding the timing of arming the ground spoilers. On the DC-8, the spoilers were armed by pulling a lever up, which would then automatically deploy them upon wheel spin-up on the ground. Captain Hamilton preferred arming them during the flare, just before touchdown, while First Officer Rowland preferred arming them earlier on the final approach. On the day of the accident, they agreed to follow the Captain's preference. However, during the flare at 60 feet, Rowland mistakenly pulled the lever back into the full deployment position rather than just upward into the armed position. The resulting loss of lift caused the aircraft to slam into the runway at a high sink rate. Although the Captain managed to initiate a go-around, the damage to the right wing's fuel system was catastrophic. As the aircraft climbed to 3,100 feet, fire and subsequent explosions destroyed the wing's integrity, leading to a total loss of control.
Final Conclusions
The investigation concluded that the primary cause was the accidental deployment of ground spoilers in flight due to a lack of checklist discipline and a non-standard cockpit agreement. A significant contributing factor was the design of the spoiler lever, which allowed for full deployment in flight without adequate safeguards. The board of inquiry also noted that McDonnell Douglas was aware of the potential for accidental deployment but had not implemented a physical lockout mechanism that would prevent the lever from being moved to the 'extend' position while the aircraft was airborne.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Ground Spoilers
Aerodynamic surfaces on the wing used to dump lift upon landing; on the DC-8, these could be armed to deploy automatically or manually deployed in flight.
Spoiler Lever
The cockpit control used to arm or deploy spoilers; it lacked a physical gate or lockout to prevent accidental full deployment while airborne.
Interesting Facts
- 01The aircraft was a brand new DC-8-63 that had been delivered to Air Canada only three months prior to the accident, with only 453 flight hours.
- 02The impact with the runway was so severe that the number four engine and its pylon separated from the wing.
- 03The crash site was located in Toronto Gore Township, approximately 6.2 miles north of the airport.
- 04All 109 people on board were killed instantly upon the final impact.
- 05At the time of the accident, it was the second deadliest aviation accident in Canada, following Trans Canada Air Lines Flight 831.
- 06The accident remains the deadliest in the history of Air Canada.
Safety Actions & Advisories
Spoiler Lever Redesign
McDonnell Douglas was required to install a physical lockout mechanism on the DC-8 spoiler lever to prevent it from being moved to the 'ground' position while the aircraft was in flight.
Standardization of Procedures
Air Canada and other operators standardized the timing for arming spoilers to ensure it occurred during the approach phase rather than the flare.