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PPL · EASA 061 · Basics of navigation
From true heading to compass heading
True heading 250°, variation 3°W, compass deviation 2°E on this heading. Which heading do you fly on the compass?
Optional: check your working step by step.
Explanation
Going from true to compass you apply two corrections in a fixed order: variation (the Earth's magnetic field) gives magnetic, then deviation (the aircraft's own magnetism, read from the compass deviation card) gives compass. Both follow the same sign rule: east is subtracted, west is added. In the formula, C stands for compass, T for true, Var for variation and Dev for deviation.
Step by step
- True heading: 250°T.
- Variation 3°W, west is best: 250° + 3° = 253°M.
- Deviation 2°E, east is least: 253° − 2° = 251°C.
Why not the other answers
- 255° adds the easterly deviation instead of subtracting it.
- 249° subtracts the westerly variation (247°M) and then adds the deviation: both signs are reversed.
- 245° subtracts the westerly variation and then subtracts the deviation as well.
Tip. Write the chain T → V → M → D → C at the top of your log. Going from compass back to true, every sign flips.
Original questions written by FlightDesk Aero and aligned with the EASA syllabus. They are not questions from the official EASA exam bank.