🔍 Key Concepts

• Compass error vs deviation (what each one means and how they are found) • Using transits/range lines (two objects in line) to check compass accuracy • Difference between course steered and bearing taken on the same compass

💭 Think About

• If two charted objects (like a light and an aero beacon) are exactly in line, what should be true about their bearing on the chart? Compare that to what you see on your compass. • Think about whether this situation gives you information about the compass error for all headings, only for the heading you are steering, or only for that specific bearing you observed. • Ask yourself: does a single transit observation prove the whole deviation table is right, or does it only tell you something about one direction at that moment?

✅ Before You Answer

• Look up the true bearing of the transit (line between the North Light and the Aero Beacon) from the chart and compare to the 193° psc you observed. • Decide whether you are learning about deviation on 056° psc (your heading) or on 193° psc (the bearing you took). • Confirm that compass error = variation + deviation, and decide whether you actually know variation and which part of that equation this transit check can tell you.