Which item is not part of the listed basic components of an autopilot system?

Which item is not part of the listed basic components of an autopilot system?

• A. Gyros
• B. Servos
• C. Controller
• D. Transponder

Answer: (D)

Autopilot systems operate with a control loop that relies on three kinds of components: sensors to know the aircraft’s state, a computer to process the desired versus actual flight parameters, and actuators to move the flight controls. Gyros provide the attitude and rate information the system uses to understand how the aircraft is moving. The controller (or computer) runs the autopilot logic, comparing commanded modes or flight paths to the current state and issuing commands. Servos are the actuators that move the control surfaces in response to those commands. A transponder, however, belongs to the surveillance and navigation/communication side of the aircraft systems. It sends and receives signals to help ATC identify and track the airplane and does not feed data into the autopilot loop or drive control surfaces. So it isn’t a basic component of the autopilot system.

Autopilot systems operate with a control loop that relies on three kinds of components: sensors to know the aircraft’s state, a computer to process the desired versus actual flight parameters, and actuators to move the flight controls. Gyros provide the attitude and rate information the system uses to understand how the aircraft is moving. The controller (or computer) runs the autopilot logic, comparing commanded modes or flight paths to the current state and issuing commands. Servos are the actuators that move the control surfaces in response to those commands.

A transponder, however, belongs to the surveillance and navigation/communication side of the aircraft systems. It sends and receives signals to help ATC identify and track the airplane and does not feed data into the autopilot loop or drive control surfaces. So it isn’t a basic component of the autopilot system.