Private Pilot Private Exam

When converting from true course to magnetic heading, what should a pilot do with westerly variation?

1. Add it to the true course

2. Subtract it from the true course

3. Multiply it by the true course

4. Ignore it entirely

The correct answer is: Subtract it from the true course

When converting from true course to magnetic heading, the pilot should subtract the westerly variation from the true course. This is because magnetic variation, which can be westerly or easterly, reflects the difference between true north (geographic north) and magnetic north (the direction a compass points). For westerly variation, the magnetic north is to the west of true north, meaning that to align with magnetic north (and find the correct magnetic heading), you need to reduce your true course by the amount of westerly variation. This ensures that the heading given by your compass accurately reflects the desired course over the ground. In contrast, if the variation were easterly, you would add that value to the true course. Hence, understanding the direction of magnetic variation is crucial for successful navigation.