Compass Deviation

Because deviation depends upon the actual distribution of magnetic
forces within the aircraft itself, it must be obtained individually
for every magnetic compass on every aircraft. The particular procedure of
determining deviation, termed as compass swinging, ought to
be discussed within the technical purchase for each compass.
The particular net result of just about all magnetic forces of the actual aircraft (all those forces
excluding the earth’s field) is represented by a dot found
simply just behind the wings of the actual aircraft. If the aircraft can be headed
toward MN, the actual dot attracts it pole of the particular magnetic compass
(with regard to this case, the particular South Pole) yet, on this heading, does
not change its direction. The just impact is actually with amplify the
directive force of the actual earth’s field. Generally if the aircraft heads toward
magnetic east, the particular dot typically is at this point west of the compass, and even attracts
the South Pole of the actual compass, causing easterly deviation.
picture furthermore shows that the deviation can be zero on a south
heading, and westerly when the particular aircraft can be heading west.
Deviation is reduced (however not eliminated) in certain
direct-indicating magnetic compasses by adjusting the small
compensating magnets throughout the compass case. Remaining
deviation is referred to because residual deviation and even is
determined by comparison with true values. This particular residual
deviation is actually recorded on a compass correction card showing
actual deviation on various headings or the particular compass headings.
Within the compass correction card illustrated within picture,
the navigator knows which with fly a magnetic heading (MH) of
270°, the actual pilot must steer a CH of 268°.