That’s exactly what happened on July 23, 1983. Captain Bob Pearson and First Officer Maurice Quintal were flying the aircraft, but due to mechanical difficulties the fuel gauges weren’t working. This was realized during a stopover in Montreal and the plane was still allowed to fly, but the amount of fuel had to be calculated manually. Mechanics knew that the plane would need 22,300 kilograms of fuel to fly from Montreal to its destination in Edmonton, and they were also able to determine that there were 7,682 liters of fuel in the tank at that time. The flight crew then [incorrectly] calculated that they needed to add 4,916 liters from the fuel truck. Click to read more about how a simple mix-up of pounds versus kilograms had nearly disastrous consequences.