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When using the magnetic compass in NORTHERN HEMISPHERE flying, which two errors must be considered?
Choices
Variation and deviation only.
Variation/deviation are corrected by computation, not flight error.
✓ Acceleration error (ANDS) and turning error (UNOS).correct
Magnetic dip produces two dynamic in-flight compass errors in the Northern Hemisphere. ACCELERATION error (ANDS — Accelerate North, Decelerate South): on an east or west heading, accelerating swings the card toward north and decelerating swings it toward south. TURNING error (UNOS — Undershoot North, Overshoot South): rolling out of a turn onto north requires undershooting the heading and onto south requires overshooting it. Variation and deviation are geographic and installation errors, not dip errors.
Parallax error and refraction error.
Parallax/refraction don't apply to magnetic compass.
Precession error and oscillation error.
Incorrect. Precession is a gyroscopic instrument error, not a magnetic-dip error of the compass.
Why
Magnetic dip produces two dynamic in-flight compass errors in the Northern Hemisphere. ACCELERATION error (ANDS — Accelerate North, Decelerate South): on an east or west heading, accelerating swings the card toward north and decelerating swings it toward south. TURNING error (UNOS — Undershoot North, Overshoot South): rolling out of a turn onto north requires undershooting the heading and onto south requires overshooting it. Variation and deviation are geographic and installation errors, not dip errors.
FAA source: PHAK Ch 8; PHAK Chapter 8 — Flight Instrumentsbrowse the reference library →
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Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question. Reviewed by a panel of three CFIs + AI review.