AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

Autopilot Components and Their Functions

For certain situations in flight, the pilot may employ the autopilot system which flies the aircraft by using electrical signals developed in gyro-sensing units. Typically, autopilot systems comprise four basic elements: sensing elements, computing elements, output elements, and command elements. Some more advanced systems also include a feedback or follow-up system as well. For your better understanding, we will provide an overview of the general functions of each of these elements and the role they play within the autopilot system.

Before delving into the purpose of each of these elements, it is important for one to understand the purpose of the autopilot system as a whole. Although most autopilot systems are equipped with sophisticated elements, the most basic function that any system must perform is the ability to control the rudders, ailerons, and elevators of the aircraft in response to signals received through various channels within the system. Gyro-sensing units across the system are connected to flight instruments that indicate direction, rate of turn, bank, or pitch. The computer receives and uses these signals to control the operation of three servo units, those of which convert the electrical energy to mechanical energy to control the rudders, ailerons, and elevators respectively.

The autopilot system first uses its sensing elements to sense the movement of the aircraft. These instruments generate the electrical signals used by the autopilot to take corrective action and keep the aircraft on course. The three aspects of the sensing system include the attitude and directional gyros, the turn coordinator, and an altitude control. Gyros can be located either with the pilot’s instruments in the cockpit or remotely in the aircraft. Modern digital systems include additional advanced sensors, but most basic sensor systems function to monitor elements that require adjustments in pitch, roll, and yaw.

The signals are then received by the computing elements, those of which interpret the data to integrate commands and send signals to the output systems to control the aircraft. The computer relies on an amplifier to strengthen its signals for processing and for use by the output devices.

The output devices in the system are the servos that cause actuation of the flight control surfaces. They are individual devices used by each of the three channels for control, and they can operate on various power sources. Whether control surfaces are cable-actuated, hydraulic-actuated, or electro-pneumatic, autopilot servos must send output signals to control movement and must allow unimpeded control surface movement when the autopilot is not operating. Servos can operate motors, fluids, or electric signals to move the controls.

Lastly, the command unit, or flight controller, allows the pilot to tell the autopilot what to do. By pressing the desired function buttons, the pilot causes the controller to send instruction signals to the autopilot computer, enabling it to activate the proper servos to carry out the command(s). The pilot can choose to instruct the autopilot to level flight, make climbs or descents, turn to a heading, and more. Despite what some believe, there is an essential human element to autopilot functions and no aircraft can operate entirely on its own.

A final element one might encounter in a more sophisticated autopilot system is a feedback system that of which monitors and controls for over correction on behalf of the control systems. Regardless of the elements in your autopilot system, Aerospace and Defence Parts has you covered for any autopilot components you require. Owned and operated by ASAP Semiconductor, we are a leading online purchasing platform with access to an inventory of over 2 billion new, used, obsolete, and hard-to-find parts. Kick-off the parts procurement process today with the submission of a Request for Quote form for any item. Within 15 minutes, we will contact you with a personalized quote for your comparisons. For further inquiries, call or email us at any time; we are available 24/7x365!


Semiconductor's Certifications and Memberships
The only independent
distributor with a
  • All orders are fulfilled in the USA.
  • All shipments must comply with U.S.A export laws.
  • No exceptions.
fallen heroes fund logo

“We Proudly Support Intrepid Fallen Heroes Fund that serves United States Military Personal experiencing the Invisible Wounds of War : Traumatic Brain Injury (TBI) and Post Traumatic Stress (PTS). Please visit website ( and help in their valiant effort”.

Thank You for Visiting.

We Hope that You Will Visit Us Again the Next Time You Need NSN Parts and Make Us Your Strategic Purchasing Partner.

Request for Quote

We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.