Distance on the Earth

Nautical Mile (NM)

The nautical mile is the standard unit of distance used in aviation.

It is based on the dimensions of the Earth:

1 minute of latitude = 1 nautical mile

Therefore:

• 1° of latitude = 60 NM

• 1 minute of latitude = 1 NM

Kilometre (km) and Metre (m)

The metre is the basic metric unit of length.

1 kilometre = 1,000 metres

For navigation:

1 NM = 1.852 km = 1852 metres

Foot (ft)

The foot is commonly used in aviation for measurements such as altitude, elevation and height.

1 ft = 0.3048 m

Convert Between a Nautical Mile and a Kilometre

For most navigation calculations:

1 NM = 1.852 km

or approximately:

1 NM = 1.85 km

For example:

10 NM × 1.852 = 18.52 km

Measure Distances on an Appropriate Chart

Distance on an aviation chart can be measured using a navigation ruler, plotter or dividers, latitudes or the scale appropriate to the chart.

A chart scale of 1:250,000 means that one unit measured on the chart represents 250,000 of the same units on the Earth.