Sky-High Success: Ace the FAA AMT Airframe Practice Exam 2026 – Soar to New Heights!

The operating principle of the sensing device used in an autopilot system is the relative motion between a gyro and its supporting system. This is because gyroscopes work based on the principle of conservation of angular momentum, where the rotor maintains its orientation regardless of the movement of the base. Additionally, gyroscopes provide accurate measurements of pitch, roll, and yaw, making it an ideal sensing device for an autopilot system.

The other options are not correct because

A) Electrical resistance change is not a standard operating principle for autopilot systems. This option may be applicable in other sensing devices, but not in this scenario.

B) Magnetic field variation is not used in most autopilot systems as it may be influenced by external factors, making it less reliable.

D) Pressure differential may be used in altitude or airspeed sensors but is not the primary operating principle in autopilot systems.