Measuring visibility is another curious oddity. Most countries use metres. Normal instrument approaches in Australia require a forward visibility of 800 metres for pilots to land safely. Zipping around in a light aircraft needs a forward visibility of 5000 metres. Again, heading back to North America, they measure visibility in statute miles or sometimes even feet.

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This requires some mental gymnastics by pilots to remember that one statute mile is 1600 metres, so for a visibility of 800 metres, you need half a statute mile in the US.

Is this starting to make your head hurt?

Wind speed is normally measured in knots, although some countries use metres per second, while the rate of climb of an aircraft is measured in feet per minute and is globally consistent except for those countries listed earlier, including the giant land mass of China.

When it comes to weights, the fun continues. Think about Jules and Vincent in the car in the movie Pulp Fiction discussing a quarter pounder in France. Aircraft manufacturers tailor their weights to the country the aircraft will operate in. So, while the American company Boeing builds planes in pounds, they are converted to kilograms for Australian carriers. Hence the maximum take-off weight (MTOW) of a B787 is converted from 561,500 pounds to 254,692 kilograms.

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Whereas French Airbus operates under the metric system – a Royale with cheese instead of a quarter pounder – so the MTOW of an Airbus A321 is 97000 kilograms, a nice even number in the metric world. However, US operators would use 213,848 pounds as their reference weight.

Moving on to fuel, where from a Boeing perspective all the numbers are long and complex because they have been converted from pounds to kilograms. However, when the refueller fills the tank, that figure is provided to the pilots in litres. This figure then needs to be converted into kilograms depending on the specific gravity of the fuel – something that can vary with temperature – so a cross-check can be done to make sure the right amount of fuel has been loaded for the flight.

In 1983, an Air Canada flight famously ran out of fuel at 41,000 feet after the incorrect fuel order was loaded. Several factors contributed to this, but one was the mistaken conversion of pounds to kilograms in the aircraft’s computer system. Fortunately, that flight became known as the “Gimli Glider” because it still successfully landed with all 69 passengers and crew alive.

Time is the one true constant for all pilots who take to the sky. Universal Time Coordinated is behind every on-time departure or disappointing delay. It is also known as Greenwich Mean Time (GMT) or Zulu (Z) time. The zero-meridian line of longitude is located at Greenwich in the United Kingdom and is the baseline for all aviation timing.

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The east coast of Australia (in non-daylight saving time) is 10 hours ahead of Greenwich, so for pilots reviewing a flight plan, a 10am departure from Sydney will be listed as 0000Z (effectively midnight in London), while an 11.30am arrival into Melbourne is listed as 0130Z. This system comes into its own when flying across vast time zones to provide a consistent measurement of telling the time.

So, whether it is knowing a knot from a nautical mile, metres from litres, or pounds from feet, the ability to be fluent and understanding of all manner of measurements and terminology is just another skill of being a pilot.