On July 23, 1983, Air Canada Flight 143 took off from Montreal bound for Edmonton. The aircraft was a brand-new Boeing 767—one of the first commercial jets to feature advanced digital fuel-monitoring electronics. However, the plane's Fuel Quantity Indicator System was malfunctioning, requiring ground crews to manually calculate the required fuel using a dipstick.
Here is where the math went catastrophically wrong. Canada was in the middle of transitioning from Imperial units to the metric system. The new 767 measured fuel in kilograms, but the ground crew used the old conversion factor of 1.
77 pounds per liter instead of the correct 0. 8 kilograms per liter. Consequently, the plane was loaded with just 22,300 pounds of fuel instead of the required 22,300 kilograms—less than half of what was needed to reach its destination.
At 41,000 feet over Red Lake, Ontario, warning lights flashed and both engines sputtered to a dead stop. Deprived of engine power, the glass cockpit went dark, leaving the flight crew with basic emergency instruments powered only by a ram air turbine. Thankfully, Captain Robert Pearson happened to be an experienced glider pilot, and First Officer Maurice Quintal knew of a decommissioned military airbase nearby in Gimli, Manitoba.
Without power, Pearson glided the 132-ton aircraft toward Gimli. Unbeknownst to the crew, the decommissioned runway had been converted into a drag strip, complete with a crowd of spectators and families camping out for a race day. Using an advanced glider technique known as a sideslip to drop altitude without gaining speed, Pearson touched down.
The nose gear failed to lock and collapsed, sending sparks flying as the plane skidded to a halt mere feet from the crowd. Miraculously, all 61 passengers and eight crew members survived.