9.4 Distance on the Surface of the Earth
9.4.1 Distance between Two Points Along a Great Circle
1. A nautical mile is the length of an arc of a great circle that subtends an angle of one minute at the centre of the Earth.
2. The distance between two points on the surface of the earth is the arc of a circle that joins the two points.
3. To find the distance between two points along a meridian or the equator:
Distance of P and Q
= ( θ x 60 ) nautical miles