FAA Ground School Practice Test

Which of the following can distort the lines of magnetic force affecting a magnetic compass?

1. Altitude changes

2. Changes in air density

3. Electric systems and certain metals

4. Wind speed

The correct answer is: Electric systems and certain metals

The correct answer highlights that electric systems and certain metals can distort the lines of magnetic force that affect a magnetic compass. A magnetic compass works by aligning its magnetic needle with the Earth’s magnetic field. However, external magnetic fields generated by electric systems, such as radios, engines, and other electrical equipment, can interfere with this natural magnetic field. Additionally, certain metals can also influence the magnetic lines of force, leading to inaccuracies in the compass reading. This is crucial for pilots to understand because reliance on a distorted compass can lead to navigational errors, particularly in environments where magnetic interference is prevalent. Awareness of nearby electrical equipment or metallic structures is essential for maintaining accurate compass readings for safe navigation. Other choices, while they might relate to navigational aspects or flight dynamics, do not directly affect the magnetic compass in the same way. Thus, it's important for those studying aviation to recognize the significant impact of electric systems and metal on magnetic compasses to ensure safe flight operations.