Enter the wind speed, true airspeed, and angle of flight into the calculator to determine the ground speed of an aircraft.

## Ground Speed Formula

The following formula is used to calculate a ground speed.

Vg = cos (a) * vtas + ws
• Where Vg is the ground velocity/speed
• a is the angle between the horizon and the path of the aircraft in the vertical plane
• vtas is the true airspeed
• ws is the wind speed

To calculate ground speed, multiply the true airspeed by the cosine of the angle between then horizon and path, then add the wind speed.

## Ground Speed Definition

What is ground speed? A ground speed is defined as the horizontal component of the velocity of an aircraft relative to the Earth’s surface.

## Example Problem

How to calculate ground speed?

1. First, determine the angle.

Measure the angle between the horizon and the path of the aircraft in the vertical plane. For this example, the angle is 45 degrees.

2. Next, determine the true airspeed.

For this problem, the TAS is found to be 100m/s.

3. Next, determine the wind speed.

The wind speed is 5m/s.

4. Finally, calculate the ground speed.

Using the formula above, the ground speed is found to be Vg=cos(45)*100+5 = 75.710.

## FAQ

Is ground speed faster than airspeed? A ground speed can be faster than an airspeed when traveling at a low angle and when there is a strong tailwind.

Can ground speed be negative? Technically, if there is a very strong headwind paired with a slow-moving aircraft traveling at a high angle, the ground speed of an aircraft could be negative.

Does ground speed increase with altitude? Ground speed is dependent on true airspeed, and wind velocity. True airspeed depends on the density of the air around the aircraft, and sense air density changes with altitude, so will the true airspeed and ground speed. Since we know that density decreases with altitude, we can infer that ground speed will increase with an increase in altitude.