Air Canada’s DC-9-32 CF-TLV was scheduled to carry out flight 189 from Ottawa to Vancouver, with stops at Toronto and Winnipeg. The flight landed at Toronto and was parked at 07:25. A crew changed took place at Toronto and the new crew boarded the plane at 07:45. The DC-9 was pushed back at 08:01 and cleared to taxi for takeoff on runway 23L, three minutes later. Takeoff clearance was given at 08:08 and the captain advanced the throttles. The initial part of the takeoff was normal, but 46 seconds after brake release, at approx. 145 knots, the pilots felt vibrations and heard a thumping sound. The no. 2 engine RPM started to decrease and the right main gear unsafe light illuminated. With 4000 feet of runway remaining, the first officer called: “Gear is unsafe, right gear”. At a speed of 149 knots the captain rejected the takeoff. The spoilers were deployed and thrust reversers were selected. The spoilers started to retract after 2,5 seconds, upon which the captain pulled back the spoiler levers again. The spoilers retracted again four and a half seconds later. The plane crossed the end of the runway at 70 knots, traversing 457 feet of overrun before it went over a 51-ft precipice. It came to rest at the bottom of a ravine, 600 feet past the end of the runway. The fuselage was broken in two places. Although fuel tanks were ruptured, the plane did not catch fire. The aircraft accident investigation report by the Aircraft Accident Review Board Accident Report did not contain a “Probable cause”. Summarizing the findings: The no.3 tire failed on take-off and debris damaged the right gear ‘down and locked’ switch, causing a gear unsafe indication in the cockpit. Debris was also ingested by the nr.2 engine causing a loss of reverse thrust during the rejected takeoff. The company ‘s RTO procedure did not call for immediate maximum braking.