What type of variation must be added to convert true course to magnetic course?

To convert true course to magnetic course, one must account for the difference between true north and magnetic north, a concept known as magnetic variation. Magnetic variation is the angle between the geographic north pole (true north) and the magnetic north pole (magnetic north) at a particular location. This variation can either be easterly or westerly, depending on whether magnetic north is located east or west of true north.

When the magnetic variation is easterly, it means that the magnetic north is to the east of true north, and therefore, to determine the magnetic course, you would subtract the variation from the true course. Conversely, when the variation is westerly, magnetic north is to the west of true north, requiring you to add the variation to the true course.

Thus, if the answer states that westerly variation is the answer, it is likely indicating a specific situation but overlooks that variation needs to be identified properly as either east or west based on true north's location relative to magnetic north.

In general, understanding that the type of variation (westerly or easterly) must be applied appropriately helps in accurately navigating using magnetic courses. Knowing this is essential in aviation and navigation to ensure correct headings are maintained during