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2 Answers

Magnetic dip compensation

Asked by: 2245 views
Aircraft Systems

When you buy an aircraft compass you have to choose if you want it compensated for the northern or southern hemisphere.

  • What if you want to fly in both hemispheres? Do they make global/universal compasses for airplanes (non-digital)?
  • Would a compass compensated for the wrong hemisphere still work at all or would it be completely unusable? Would it be legal to use?

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2 Answers



  1. LTCTerry on May 05, 2021

    A compass aligns itself with the Earth’s magnetic field – vertically and horizontally. The magnetic field is parallel to the ground over the Equator and perpendicular at the poles.

    When far north, the north indicating end of the compass points down towards the magnetic north pole. This means the opposite end is tilted upwards, potentially dragging on the inside of the top of the compass housing.

    A good compass has some weight on one end to balance out the downward pitch and ensure free movement.

    As you get closer to the southern magnetic pole the *opposite* end dips downward – needing a weight on the opposite end.

    Good compasses are weighted for the region of the world in which they are used.

    The Earth is pretty fascinating!

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  2. KDS on May 07, 2021

    LTC Terry,

    I never before knew about the weighting on good compasses. Thanks for sharing.

    KDS

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