The Earth
The Solar System & Time
Charts
Using Aeronautical Charts
Basics of Navigation
Distance, Speed & Time
Vertical Navigation
Fuel Planning
Practical Navigation Techniques
Radio Navigation
Practice Exam

CRP-1: Calculating Track & Groundspeed

Example

You are flying on a heading of 210°T at a true airspeed (TAS) of 100 knots. The forecast wind is 100/20. What do you expect your track over the ground and ground speed to be?

1 Slide the airspeed dot down onto the horizontal line at the top of the wind grid

2 Place the wind direction (100°T) under the index by rotating the compass rose.

Note that “100/20” is shorthand for wind from 100° at 20 knots

3 Vertically down from the airspeed dot, mark a cross at the wind speed (20kts)

4 Slide the airspeed dot up to your true airspeed (105kts)

5 Place your heading (210°) under the index by rotating the compass rose

6 The cross is now indicating your groundspeed and drift:

Groundspeed = 114 knots
Drift = 9° right (starboard)
So from a heading of 210° with 9° right drift, the track is 219°

Gross Error Checking

Always make sure to do some gross error checking!

If the wind is blowing from the right, your track should be to the left of your heading
If the wind is blowing from the left, your track should be to the right of your heading
If there is a tailwind, your groundspeed should be faster than your airspeed
If there is a headwind, your groundspeed should be slower than your airspeed