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Magnetic deviation refers to compass error caused by
Choices
the difference between true and magnetic north.
That's variation, not deviation.
✓ magnetic fields generated by metal and electronics in the airplane itself.correct
Deviation is compass error caused by the airplane's own magnetic fields: metal structure and electrical equipment deflect the compass needle. Deviation varies by heading and is recorded on a deviation card mounted near the compass. Deviation = compass error from the airplane's own magnetic environment (radios, wiring, magnetized metal). Each compass has a calibration card showing residual error per heading after the swing. Pilot uses TVMDC — True → (Variation) → Magnetic → (Deviation) → Compass — to convert between true course and the heading to fly by compass.
atmospheric pressure changes.
Atmospheric pressure doesn't affect the compass.
altitude above sea level.
Altitude doesn't directly affect compass.
Why
Deviation is compass error caused by the airplane's own magnetic fields: metal structure and electrical equipment deflect the compass needle. Deviation varies by heading and is recorded on a deviation card mounted near the compass. Deviation = compass error from the airplane's own magnetic environment (radios, wiring, magnetized metal). Each compass has a calibration card showing residual error per heading after the swing. Pilot uses TVMDC — True → (Variation) → Magnetic → (Deviation) → Compass — to convert between true course and the heading to fly by compass.
FAA source: PHAK Ch 8, Ch 16; 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.