6.34 Triangle of Velocities

The triangle of velocities is a vector diagram used in air navigation to show the relationship between:

Aircraft movement through the air
Wind movement over the ground
Aircraft movement over the ground

It is used to calculate the heading to steer, the expected track made good, the groundspeed, the wind correction angle, and the effect of drift.

6.34.2 Identify and label the three vectors of the triangle of velocities. 

The triangle of velocities has three vectors:

1. Air vector

This represents the aircraft’s movement through the air.

It is labelled with:

Heading
The direction in which the aircraft is pointed.

TAS
True airspeed, the aircraft’s speed through the air mass.

Example label:

HDG 075° / TAS 100 kt

2. Wind vector

This represents the movement of the air mass over the ground.

It is labelled with:

Wind direction
The direction from which the wind is blowing.

Wind speed
The speed of the wind.

Example label:

W/V 320°/20 kt

Important: wind is always given as the direction it is from, but on the triangle it is drawn in the direction it is blowing to.

For example, a wind 320°/20 kt is drawn towards 140°.

3. Ground vector

This represents the aircraft’s actual movement over the ground.