[3] All 100 passengers and 9 crew on board were killed, and at the time it was Canada's second deadliest aviation accident after Trans-Canada Air Lines Flight 831.

The aircraft involved was a McDonnell Douglas DC-8 60 series, powered by four Pratt & Whitney JT3D engines and delivered new to Air Canada just three months prior to the accident.

[9] Captain Peter Cameron Hamilton and First Officer Donald Rowland[10] had flown on various flights together before, and had an ongoing discussion on when to arm the ground spoilers.

By raising the aircraft's nose (pitching up), lift momentarily increases, reducing the descent rate, and the main wheels may then gently contact the runway.

The aircraft began to sink heavily and the captain, realizing what had happened, pulled back on the control column and applied full thrust to all four engines.

[4] The nose lifted, but the aircraft still continued to sink, hitting the runway with enough force that the number four engine and pylon broke off the wing, and the tail struck the ground.

The aircraft then went into a violent nose dive, striking the ground at a high velocity of about 220 knots (410 km/h; 250 mph) and killing all 100 passengers and the nine crew members on board.

The plane dug a furrow 8 or 10 feet (2 or 3 m) deep, less than 60 metres (200 ft; 66 yd) from the home of the Burgsma family, in which 10 persons lived, with the crash explosion blowing out their windows.

[18] In June 2002, Castlemore resident Paul Cardin, who had been inspired by a November 2001 Toronto Sun article revisiting the Flight 621 crash scene, discovered aircraft wreckage and possible human bone shards at the site.

Continuing searches of the crash site by archaeologist Dana Poulton and Friends of Flight 621 (a Brampton-based advocacy group founded by Cardin) produced hundreds of additional human bone fragments.

In January 2007, the landowners, in conjunction with the property developers, filed an application to designate a section of the crash site as a cemetery and memorial garden.

Diarmuid Horgan, coordinator of the memorial site, said that he hoped the dedication ceremony would help victims' families find closure.