Definition
An autopilot system is an aircraft flight control system that automatically maintains or changes the airplane's attitude, heading, altitude, or flight path without continuous manual input from the pilot. It uses sensors to detect the aircraft's current state, a computer to compare that state to the pilot's selected targets, and servos that move the flight controls to correct any difference.
Plain English
A system that flies the aircraft for the pilot. The pilot tells it what to do (hold this heading, climb to this altitude, follow this course), and the autopilot moves the controls to make it happen.
Context Anchor
Seen in instrument flying when discussing cockpit automation, workload management, altitude control, course tracking, and autopilot mode selection.
Derivation
From Greek 'auto' meaning self, and 'pilot' meaning the person who steers a ship or aircraft. So 'autopilot' simply means 'self-pilot' -- a system that does the pilot's work of holding the aircraft on course.
Why Pilots Care
Reduces pilot workload and fatigue during instrument flight or long cross-country segments, allowing greater attention to navigation, communication, and systems monitoring.
Analogy
An autopilot system is like cruise control with steering help: it can hold what you set, but it does not decide where you should go or notice every problem for you.
Intuition Check
Autopilot does not mean the aircraft is flying itself independently. It means the aircraft is following selected commands while the pilot remains in charge and must keep monitoring it.
Example Sentence 1
After leveling off in cruise, she engaged the autopilot to hold heading and altitude while she reviewed the approach plate.
Example Sentence 2
Before hand-flying the missed approach, the pilot disconnected the autopilot system and resumed manual control.