AI.II.I.K9FAA-S-ACS-25 · Nov 2023Knowledge
Magnetic compass errors.
Magnetic compass errors.
Bottom line
Variation is the difference between true and magnetic directions, and it does not change with the heading of the aircraft. Deviation is a compass error created by magnetic fields in the aircraft, and it depends on the aircraft heading. Turning error causes the compass to lead turns to the north or south and lag turns away from the north or south.
Key numbers
| Number | What it means |
|---|---|
| some 1,300 miles between the magnetic North Pole and the geographic North Pole | Pole offset |
| magnetic direction indicator required for VFR flight during the day | Day VFR equip |
FAA references
- PHAK ch. 0 (p. 0-400) — FAA-H-8083-25C (2023)
- AFH Glossary (p. G-16) — FAA-H-8083-3C
- 14 CFR 91.205 (Powered civil aircraft with standard U.S. airworthiness certificates: Instrument and equipment requirements.) — eCFR current as of 2026-03-05
- AIH ch. 3 (p. 3-39) — FAA-H-8083-9B
- AFH ch. 2 (p. 2-22) — FAA-H-8083-3C
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