Units of measurement

Throughout the world, different units of measurement are used. For example, in America the standard units are feet/inches for height, fahrenheit for temperature and gallons for volume. Here in NZ we use meters, degrees celsuis and litres.

Back in the 18th century the French were seeking to create international standard units of measurement (SI Units). This system is based off all measurements being powers of 10. Some fundamental units are as follows;

• Length – Meter (m)
• Time – Seconds (s)
• Mass – Kilograms (Kg)
• Temperature – Kelvin (K)

Degrees Celsius can also be used as it is liner with Kelvin

There are also units that are made up from a combination of the fundamental units. For example, speed is expressed as distance covered over a specified time like kilometers per hour (Km/H). This would mean that the SI unit for speed is actually meters per second (m/s) which is ideal for calculations. Some derived units are as follows;

• Force – Newtons (N) – (Kg m/s^2)
• Work – Joule (J) – (Nm)
• Power – Watt (W) -(Nm/s)

With aviation being international by its nature, there is a need for standardised units which can be used by aviators around the globe.

While SI Units are ideal for describing and experimenting with the physics of flight, there are some more practical units we use as pilots. Some non-standard units used in aviation are as follows;

• Distance – Nautical mile (Nm)
• Height – Feet (ft)
• Speed – Knots (Kts) – (Nautical mile per hour)