How to Figure out Ground Speed in a Plane

The basics of ground speed.

If you've ever been flying and look out the window and wonder how fast you're going, you're not alone. The speed of an airplane's spedometer is not the accurate speed of the plane because of the wind, so asking the flight attendant to find out how fast you're going isn't going to work. You need to find how fast you're crossing the ground, or the ground speed.

Things You'll Need

• Map with a key
• Calculator
• Ruler
• Stopwatch

Instructions

1. Place the map of where you're flying over on your lap. Locate where you're flying over right now. The easiest way to do this is to pick the biggest thing around and find that on the map.

2. Locate the key on the map and, with your ruler, find out how many miles equals an inch. Look out the window and find the place you're flying over on the map and mark that spot on the map.

3. Watch the scenery pass for 1 minute. Mark the place on the map where you are flying after 1 minute. Measure the distance from the first spot to the next spot. Compare that measurement to the scale of the map to come up with a real distance in miles or feet. Now you have a distance that you've traveled, your speed is just a ratio of distance and time.

4. Figure out the math. Let's put this is real numbers. Let's say you measured that you went 10 miles in 1 minute. That means in 60 minutes, or 1 hour, you would travel 60 times that amount: 60 X 10 miles = 600 miles. In one hour, you would go 600 miles, or you're going 600 miles per hour.

Tips & Warnings

• Paying attention to your route as you fly makes this a lot easier.

Resources

• NASA website on how to find ground speed.