Acceleration Error

 (magnetic Compass Error).An error in the indication of a magnetic compass that shows up when the aircraft accelerates or decelerates while flying on an easterly or westerly heading. The float in an aircraft magnetic compass is unbalanced to compensate for the downward pull of the vertical component of the earth's magnetic field (dip error), and the inertia caused by a change in speed acts on this unbalanced condition. When the aircraft accelerates on an easterly or westerly heading, the compass indicates that the aircraft is turning to the north, and when it decelerates on either of these headings, the compass indicates that the aircraft is turning to the south.