What is the mnemonic for compass turns in the northern hemisphere?

• A. Unos
• B. Undershoot North, Overshoot South
• C. North overshoot
• D. Overshoot

Answer: (A)

In the Northern Hemisphere, there’s a magnetic compass turning error that shows up when you change headings during a turn. To help remember how it behaves, use the mnemonic UNOS: Undershoot North, Overshoot South. This means when you’re turning toward a north heading, the compass tends to lag behind, so you reach the north heading a bit later than your actual aircraft heading—your indicated heading undershoots north. When you’re turning toward a south heading, the compass tends to lead, so you pass the south heading a bit before the actual heading—your indicated heading overshoots south. This pattern is a hemispheric thing, tied to the way the magnetic field and the compass respond during turns.