RK Bali, Air Navigation
Magnetism and Compasses: DGCA Air Navigation questions
The Earth's field meets the surface at an angle except at the magnetic equator. Its horizontal part, H, aligns the compass; its vertical part, Z, causes dip and with it the compass's turning and acceleration errors.
Its 100 questions are mostly descriptive, from variation and compass swings to flux valves, with a few dip sums where Z equals H times the tangent of dip. Exam sessions have featured 20 of these.
Acceleration error is nil on north and south headings and largest on east and west; in the northern hemisphere it shows an apparent turn towards north, and the southern hemisphere reverses it. Turning in the north, roll out before the compass reaches north and after it passes south.
0 answered·5 free questions·0 right
Question 1 of 5
The magnetic north pole seems to rotate around the geographical north pole. A complete rotation takes about:
Question 2 of 5
In the areas close to the magnetic poles compasses are not to any use in air navigation, mainly because:
Question 3 of 5
Magnetic dip at 40°, H value = 23 unit, value of Z and T will be.
Question 4 of 5
In direct reading magnetic compass, the effect of dip is countered by:
Question 5 of 5
Compass deviation is caused by:
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