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

Triangle of Velocities

The wind will almost never be a direct headwind or crosswind, so the wind will cause changes to both our groundspeed and track. In reality, we plan a flight from A to B at our aircraft’s typical cruising speed and use the forecast wind to calculate the:

Required Heading to fly in order to track a straight line from A to B
Groundspeed we will fly at, so that we can determine an estimated time of arrival overhead B

However, in the Navigation Exam they often ask us to calculate any of these components. For example, you may be asked to find the wind velocity when given the heading, track, airspeed, and groundspeed.

We could use the Triangle of Velocities to do any of these calculations. This would require accurately drawing out each direction with a protractor and making the length of each line proportional to the speed along that line (e.g. 100 knot airspeed = 10cm line, 10 knot wind speed = 1cm line).

In reality however, a Navigational Computer (usually the CRP-1 for PPL) is used for these calculations.

The Navigation Computer also gets called the CRP-1, the flight computer, or often the ‘whiz wheel’. You will need one for your navigation flight training and several of the exams. The next lessons show how to calculate the different components with the CRP-1.

The CRP-1 Navigational Computer