Relative wind definition

Relative wind is created by the movement of an object through the air. To better understand the relative wind, we give an example:

Imagine a person sitting in a car on a no-wind day. If that person takes his hand out of the window, he will not feel the wind around his hand.

Now, if the car starts moving at a speed of 40 km/h (25 mph), that person will feel the wind at a speed of 40 km/h (25 mph) around his hand. This wind, which is created by the movement of a person’s hand in the air, is called relative wind.

In this lesson, we look at the relative wind in aviation.

In aeronautics, the relative wind is created by the movement of an aircraft or an airfoil through the air. In other words, the wind produced by the movement of the aircraft in the air is called relative wind. Relative wind is parallel to and opposite the flight path of the aircraft or airfoil.

• If the flight path of the aircraft is forward, then the relative wind is backward

• If the flight path of the aircraft is forward and upward, then the relative wind is backward and downward

• If the flight path of the aircraft is forward and downward, the relative wind is backward and upward

You should not confuse the actual flight path with the aircraft flight attitude.
For example, the fuselage may be parallel to the horizon while the airplane is descending, which can be seen in the image below.

As you can see in the picture, the airplane flies in level attitude, but its actual flight path is forward and downward so, the relative wind is backward and upward which is parallel to and opposite the airplane flight path.

Understanding what relative wind is in aviation is a prerequisite for being able to understand the angle of attack (AOA). In the next lesson, we will examine the angle of attack.