Private Pilot Private Exam

What causes deviation in a magnetic compass?

1. Magnetic fields within the aircraft distorting the lines of magnetic force

2. Environmental magnetic fields

3. The Earth's rotational forces

4. The altitude of the aircraft

The correct answer is: Magnetic fields within the aircraft distorting the lines of magnetic force

Deviation in a magnetic compass is caused by magnetic fields within the aircraft that distort the lines of magnetic force. This distortion can occur because various components of the aircraft, such as electrical equipment, metal structures, or magnetic instruments, can produce localized magnetic fields. These fields interfere with the compass's ability to point accurately to magnetic north, leading to erroneous readings or deviation from the true magnetic heading. Understanding this concept is essential for pilots, as they must be aware that the magnetic compass is not only influenced by the Earth's magnetic field but can also be affected by the magnetic environment of the aircraft itself. Pilots typically need to adjust for this deviation during pre-flight checks and consider it when interpreting compass readings in flight to ensure accurate navigation.