On July 23, 1983, Air Canada Flight 143 took off from Montreal bound for Edmonton. The aircraft was a brand-new Boeing 767, the first in Air Canada's fleet to use the metric system for fuel calculations instead of imperial measurements. However, a malfunctioning Fuel Quantity Indicator System forced the crew to manually calculate the fuel load using a dipstick measurement during refueling.
The ground crew measured 11,584 liters of fuel remaining in the tanks and needed to determine how many kilograms to add to reach the required 22,300 kilograms. Instead of multiplying the volume by the density factor for kilograms per liter (0. 803 kg/L), they used the factor for pounds per liter (1.
77 lb/L). By treating pounds as kilograms, the math check passed on paper, but the plane took off with less than half of its required fuel.
At 41,000 feet over Red Lake, Ontario, warning lights chimed as the left engine flamed out. Shortly after, the right engine died too, turning the massive jetliner into an unpowered glider. The loss of engine power also extinguished electrical power, disabling digital flight instruments and hydraulic control.
Luckily, a emergency Ram Air Turbine deployed automatically, providing just enough hydraulic pressure to move the flight controls.
Captain Bob Pearson, an experienced glider pilot, teamed up with First Officer Maurice Quintal to calculate a glide path. Quintal suggested landing at a decommissioned Royal Canadian Air Force base in Gimli, Manitoba, where he had previously trained. Unbeknownst to them, the base's runway had been converted into a dragstrip, and a crowd was actively attending a sports car event that day.
Using advanced soaring maneuvers like a sideslip to drop altitude without gaining speed, Pearson touched the 767 down on the dragstrip, blowing out tires and sparking against the steel guardrail. All 61 passengers and 8 crew members survived without serious injuries, earning the aircraft the legendary nickname 'The Gimli Glider.'