CEA Fundamentals Block 3 Practice Test

Heading relative to magnetic north is provided by the magnetic compass. The compass uses a magnetized needle that points toward magnetic north, but the aircraft’s metal structure and installed equipment distort the local magnetic field. This distortion causes deviation from the true magnetic north, which is why pilots apply a deviation correction using the aircraft’s deviation card to read an accurate magnetic heading. Other instruments like the HSI, RMI, and ADI rely on different systems (gyros or radio signals) and display heading or attitude without needing this manual deviation adjustment. So the magnetic compass is the instrument that both shows heading to magnetic north and requires a deviation correction.