FAA Ground School Practice Test

Under what condition are the indications of a magnetic compass most accurate during flight?

1. During sharp maneuvers

2. Only in straight-and-level unaccelerated flight

3. While climbing

4. During descent

The correct answer is: Only in straight-and-level unaccelerated flight

The indications of a magnetic compass are most accurate during straight-and-level unaccelerated flight because this condition minimizes the influence of external forces that can cause inaccuracies in compass readings. In straight-and-level flight, the airplane maintains a constant attitude without changes in speed or direction, allowing the compass to reflect the true magnetic heading more reliably. During sharp maneuvers, climbing, or descending, the compass can be affected by acceleration, turns, and changes in altitude. These factors can introduce errors such as magnetic dip and turning errors. Specifically, during turns, the compass tends to lag behind the actual heading due to the inertia of the liquid in the compass and the change in the aircraft's orientation. Additionally, during climbs and descents, the compass can exhibit errors due to the combination of vertical movement and the Earth's magnetic field's influence. Therefore, for optimal accuracy of the magnetic compass, straight-and-level unaccelerated flight is essential, resulting in dependable adherence to true magnetic headings.