Definition
A type of autopilot servo design in which the servo drives the flight control surface directly to a commanded position. The autopilot computer determines where the control surface needs to be, and the servo moves it to that exact position. This contrasts with rate-based systems, which command the servo to move at a certain speed rather than to a specific position.
Plain English
The autopilot tells the servo, 'put the control surface here,' and the servo moves it to that exact spot. The system thinks in terms of where the controls should be, not how fast to move them.
Context Anchor
Seen when comparing how different autopilot systems sense errors and make corrections.
Why Pilots Care
Knowing whether your autopilot is position-based or rate-based helps you understand how it will respond, how it handles disturbances, and what kind of failure behavior to expect. Position-based systems tend to feel more direct, while rate-based systems often feel smoother but slower to correct.
Intuition Check
Do not read position based as meaning only GPS location. In this autopilot context, position means where the airplane is relative to the reference the system is trying to hold or track.
Example Sentence 1
Because the autopilot in this aircraft is position based, the servos move each control surface directly to the angle the computer calls for.
Example Sentence 2
When the aircraft drifted two degrees right of course, the position-based system commanded an immediate left turn to return to the reference.