ASN Aircraft accident McDonnell Douglas DC-8-63 CF-TIW Toronto International Airport, ON (YYZ)
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Status:Accident investigation report completed and information captured
Date:Sunday 5 July 1970
Type:Silhouette image of generic DC86 model; specific model in this crash may look slightly different
McDonnell Douglas DC-8-63
Operator:Air Canada
Registration: CF-TIW
MSN: 46114/526
First flight: 1970
Total airframe hrs:453
Engines: 4 Pratt & Whitney JT3D-7
Crew:Fatalities: 9 / Occupants: 9
Passengers:Fatalities: 100 / Occupants: 100
Total:Fatalities: 109 / Occupants: 109
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:11 km (6.9 mls) N of Toronto International Airport, ON (YYZ) (   Canada)
Phase: Landing (LDG)
Nature:Domestic Scheduled Passenger
Departure airport:Montreal-Dorval International Airport, QC (YUL/CYUL), Canada
Destination airport:Toronto International Airport, ON (YYZ/CYYZ), Canada
Air Canada flight 621 was a routine early morning flight originating from Montreal-Dorval International Airport, QC (YUL), with destination Toronto International Airport, ON (YYZ). The DC-8-63 plane, a relatively new airplane which had been delivered just over two months ago, departed at 07:17 for a flight which was to take just over 50 minutes. The captain was pilot flying. The enroute and descent portion of the flight were uneventful. At a distance of 8 miles from Toronto Airport, about 08:02, the "Before-Landing Check" was made. This included the lowering of the undercarriage and according to Air Canada procedures should include arming the spoilers. This item however was intentionally omitted. On previous flights were the captain and first officer had flown together they had disagreed on when to arm the spoilers. Both men did not like to arm the spoilers at the beginning of the final approach, fearing that this increased the chance of inadvertent spoiler activation. The captain preferred to arm the spoilers on the flare, while the first officer preferred to arm and extend them on the ground. Although both procedures where contrary to company policy, it was agreed between them that when the captain was flying the aircraft, the first officer would cause the spoilers to be extended on the ground, and when the first officer was flying the captain would arm the spoilers on the flare.
However on this particular occasion, the captain and first officer had a discussion about when the spoilers should be armed. The captain finally ordered: "All right, give them to me on the flare", which was contrary to their personal agreement on previous flights.
Power was reduced then on the aircraft for the purpose of the flare and the captain gave the order to the first officer by saying "O.K."; and immediately thereafter the ground spoilers were deployed. The aircraft was about 60 feet above runway 32 at that time and began to sink rapidly. The captain immediately noticed what had happened, applied full throttle to all four engines and pulled back the control column. The nose came up as the aircraft continued to sink. Realizing what he had done, the first officer apologized to the captain. The plane than struck the runway heavily, causing the number 4 engine and pylon to separate from the wing. It fell on the runway along with a piece of the lower wing plating, allowing fuel to escape and subsequently ignite. The DC-8 rose back into the air, at which time the ground spoilers retracted, and climbed to an altitude of 3100 feet. During this climb, fire and smoke were seen trailing behind the aircraft intermittently. The crew wanted to circle for an emergency landing on runway 32. This was not possible because of debris on the runway, so the controller suggested a landing on runway 23. About two and a half minutes after the initial touchdown an explosion occurred in the right wing outboard of the number 4 engine location causing parts of the outer wing structure to fall free to the ground. Six seconds later, a second explosion occurred in the vicinity of number 3 engine and the engine with its pylon ripped free of the wing and fell to the ground in flames. Six and one half seconds later, a third explosion occurred which caused the loss of a large section of the right wing, including the wing tip. The airplane then went into a violent manoeuvre, lost height rapidly and at the same time more wing plating tore free following which the DC-8 struck the ground at a high velocity, about 220 knots in a left wing high and nose low attitude.

Probable Cause:

PROBABLE CAUSE: The Canadian investigation report did not conform to ICAO standards and did not contain a probable cause as such.

Accident investigation:

Investigating agency: Commission of Inquiry
Status: Investigation completed
Duration: 208 days (7 months)
Accident number: final report
Download report: Final report

Improper flap/slat usage
Heavy landing
Loss of control

» Bill Lane
» Air Canada 621 photos

Follow-up / safety actions

FAA issued 1 Airworthiness Directive

Show all...


photo of DC-8-63-
Flight path reconstruction

Video, social media
Brampton’s LARGEST AIR DISASTER…Flight 621::: 1970

This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Montreal-Dorval International Airport, QC to Toronto International Airport, ON as the crow flies is 503 km (315 miles).
Accident location: Approximate; accuracy within a few kilometers.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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  • 2nd worst accident (at the time)
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