Investigation Summary
Air Canada Flight 189 was a multi-leg service originating in Ottawa with scheduled stops in Toronto, Winnipeg, and Vancouver. Following a crew change at Toronto (YYZ) at 07:45 EDT, the accident sequence began 46 seconds after brake release as the aircraft reached approximately 145 knots. The failure of the number 3 tire sent debris into the right main gear 'down and locked' switch, which immediately illuminated the gear unsafe light in the cockpit. Simultaneously, the number 2 engine ingested tire fragments, causing a decrease in RPM and a subsequent loss of reverse thrust capability on the right side. The first officer called out the unsafe gear indication, and the captain initiated the rejected takeoff at 149 knots. The aircraft continued to accelerate briefly to a peak speed of 154 knots before decelerating. During the deceleration, the spoilers were deployed but retracted twice due to mechanical or pilot input issues, reducing the effectiveness of the braking. The aircraft crossed the runway threshold at 70 knots and traveled 457 feet across the overrun area before falling 51 feet into the ravine. The investigation highlighted that the decision to abort was delayed by four seconds after the initial warning, and that the airline's procedures at the time did not emphasize immediate maximum braking during a high-speed rejected takeoff.
Final Conclusions
The Aircraft Accident Review Board identified multiple contributing factors rather than a single probable cause. The primary mechanical trigger was the failure of the number 3 tire and subsequent debris damage to the gear sensors and number 2 engine. However, the board noted that a more immediate decision to abort the takeoff would have likely prevented the overrun. The investigation also criticized the lack of adequate training for emergency braking and the presence of a deep ravine at the end of the runway, which significantly increased the severity of the accident.
Video Analysis
Disastrous Takeoff At Toronto International Airport: Air Canada 189 — A detailed look at the 1978 Air Canada Flight 189 accident, where a tire blowout and a delayed rejected takeoff led to a DC-9 plunging into a ravine at Toronto Pearson.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Systems & Failure Modes
Landing Gear Warning System
A switch in the landing gear mechanism was damaged by tire debris, triggering a 'gear unsafe' light that prompted the crew to abort the takeoff.
Spoilers
The aircraft's spoilers, used for aerodynamic braking, retracted twice during the deceleration sequence, reducing the stopping force.
Thrust Reversers
The number 2 engine's ability to provide reverse thrust was compromised after ingesting tire fragments during the initial failure.
Interesting Facts
- 01The aircraft was carrying a full load of fuel but did not catch fire after the crash.
- 02The two fatalities occurred at the site of the forward fuselage split.
- 03The number 2 engine suffered a loss of reverse thrust due to tire debris ingestion.
- 04The investigation found a four-second delay between the warning light and the pilot's decision to abort.
- 05The same ravine was the site of the Air France Flight 358 crash 27 years later in 2005.
Safety Actions & Advisories
Tire Inspection Standards
The investigation recommended greater scrutiny and more rigorous inspection standards for aircraft tires to prevent disintegration.
Emergency Braking Training
Investigators criticized the existing level of training for emergency braking and recommended improved pilot training for high-speed rejected takeoffs.