A Kilogram of Trouble
On July 23, 1983, Air Canada Flight 143, a brand-new Boeing 767-233, departed Montreal for Edmonton. The aircraft, registration C-GAUN, was one of the first 767s in the airline's fleet and the first to use metric units for fuel calculations. This distinction caused the near-catastrophe. Before takeoff, ground crews discovered the plane's Fuel Quantity Information System (FQIS) was inoperative, meaning the digital fuel gauges were blank. This required the crew to calculate the fuel load manually by using dripsticks to measure the physical volume of fuel in the tanks.
The problem arose from a critical conversion error. The ground crew and flight crew were accustomed to calculating fuel in pounds, but the new 767 required kilograms. They used the incorrect conversion factor of 1.77 pounds per litre instead of the correct 0.8 kilograms per litre. This mistake resulted in the aircraft being loaded with 22,300 pounds of fuel instead of the required 22,300 kilograms. The plane took off with less than half the fuel needed to reach its destination. The error went undetected by multiple crew members, each of whom made the same independent calculation mistake.
The Silent Descent
While cruising at an altitude of 41,000 feet (12,500 meters) over Red Lake, Ontario, a cockpit warning system chimed, indicating a fuel pressure problem. Soon after, the left engine flamed out, followed minutes later by the right. The 132-ton jetliner became a glider. The loss of both engines also cut all primary electrical power, blanking the glass cockpit displays. A small, propeller-driven emergency generator called a Ram Air Turbine (RAT) automatically deployed from the fuselage, providing just enough power for essential hydraulic systems and a few basic flight instruments.
Captain Robert "Bob" Pearson, an experienced glider pilot, took control of the powerless aircraft. First Officer Maurice Quintal began calculating their glide distance to find a suitable landing site. Their planned diversion to Winnipeg was out of reach. Using air traffic control radar and his own knowledge, Quintal identified a potential landing spot: a decommissioned Royal Canadian Air Force base at Gimli, Manitoba. For 17 minutes, the 767 descended in silence.
A Racetrack Landing
The pilots had no way of knowing that their chosen runway was no longer an abandoned airstrip. On that Saturday, Gimli Motorsports Park was hosting a "Family Day" for a local sports car club, and the runway was active as a drag strip, complete with race cars, campers, and spectators. A steel guardrail had even been installed down the middle of the pavement.
As the silent airliner approached, Pearson realized they were too high and fast for a standard landing. With no engine power to go around for another attempt, he executed a maneuver from his glider playbook: a forward slip. By applying opposite rudder and aileron, he forced the aircraft to fly partially sideways, dramatically increasing drag to lose altitude without gaining speed. This technique is common in gliders but almost unheard of in a large passenger jet.
The main landing gear was lowered by a gravity drop, but the nose gear failed to lock into place. This turned out to be a fortunate failure. Upon touchdown, the nose gear collapsed, causing the aircraft's nose to slam onto the runway. This created friction that helped slow the plane and prevented it from crashing into the crowd gathered at the end of the strip. The plane skidded to a stop, its main gear straddling the guardrail. All 69 people on board survived.