Distance on the Earth

Nautical Mile (nm);

• The nautical mile has its origin in its relationship to the size of the earth, where 1 minute of latitude is equal to 1 nm, measured along a meridian of longitude.
• Since the Earth is not a perfect sphere, and to help account for certain variations, it has been decided to introduce the international nautical mile, which is a fixed distance exactly equal to 1,852 m (6,080ft).

Kilometre (km) and Metre (m);

• In the international system of units (SI), the fundamental unit is the metre, which was originally defined by the French Academy of Sciences in 1791 as ‘the 1/10,000,000 part of the distance over the earth’s surface from the equator to the North Pole along the meridian of longitude that passes through Paris’.
• The kilometre is thus 1,000 m in length and hence is approximately 1/10,000 of the distance from the equator to the North pole.
• In the 1980s, the measurement of a metre was refined and is now defined as ‘the distance travelled by light in a vacuum in 1/299,792,458 of a second’.

Foot;

Calculate Between a Nautical Mile and a Kilometre.

• 1 nm = 1.85 km = 1850 m

Measure distances on an appropriate chart.

To measure distances on an aviation chart, you can use the scale provided on the chart.