When does a compass read most accurately during turns?

A compass reads most accurately during turns when positioned over the equator because the magnetic declination is minimal relative to true north at the equator. At this location, the magnetic field lines are more vertical, allowing the compass to align more directly with the Earth’s magnetic field, leading to less compass error. This condition helps reduce the influences of lateral acceleration and magnetic variation, which can both introduce errors in compass readings, particularly during maneuvers like turning.

In contrast, other locations, such as areas near the poles, have significant magnetic variation that can cause the compass to behave erratically during turns due to the more horizontal orientation of magnetic lines, which can lead to more pronounced errors. Also, flying at high altitudes or over water does not inherently improve the accuracy of the compass; these factors can still present their own challenges related to compass reliability and reference. Being near airports may not notably enhance compass accuracy either, as many external factors can affect navigation and compass readings in such areas.