Magnetic Compass

Question 1

How does the Magnetic Compass work?

Answer 1

The Magnetic Compass has a simple bar magnet with 2 poles. The bar magnet pivots freely and align itself automatically with the earth’s magnetic field.

Note: Bar magnet is fastened to a float assembly which is housed in a bowl filled with acid-free white kerosene.

Question 2

What limitations does the Magnetic Compass have?

Answer 2

The float assembly of the compass is balanced on a pivot, which allows free rotation of the card and allows it to tilt at an angle up to 18°

Question 3

What are the various compass errors?

Answer 3

1. Oscillation Error - Erratic movement of the compass card caused by turbulence or rough control technique.
2. Deviation Error - Due to electical and magnetic disturbance in the aircraft.
3. Variation Error - Angular difference between true and magnetic north; reference isogonic lines of variation.
4. Dip Errors - Error increases as I fly closer to the poles.

• Acceleration Error - On an East or West heading, while accelerating, the magnetic compass shows a turn to the north, and when decelerating, it shows a turn to the south.
  
  • ANDS - Accelerate North, Decelerate South
• Northerly turning errors - The compass leads in the south half of a turn and lags in the north half of a turn
  
  • UNOS - Undershoot North Overshoot South