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

  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.