Definition
A mechanical override mechanism inside an autopilot servo that allows the pilot to manually move the flight controls against the autopilot's commands. A magnetic clutch holds the servo engaged with the control surface during normal autopilot operation, while a spring provides a force that the pilot can overcome by applying pressure to the controls, disconnecting or slipping the servo so the aircraft can be hand-flown without first switching the autopilot off.
Plain English
It's a built-in safety feature in the autopilot that lets the pilot grab the controls and fly the aircraft by hand, even while the autopilot is still on. The pilot can simply push or pull against it and the autopilot will give way.
Context Anchor
Seen in discussions of older or simpler autopilot and aircraft stabilization systems, especially where the system explains how control movement is held, resisted, or centered.
Derivation
The name describes the two parts working together: a magnetic component (an electromagnet acting as a clutch) and a mechanical spring. The magnet holds the servo connected to the controls; the spring sets how much pilot force is needed to override it.
Why Pilots Care
Prevents abrupt control movements during autopilot disconnect and ensures the aircraft remains stable during the transition to manual flight.
Analogy
Think of a cabinet door held shut by a magnet while a small spring helps return a latch to its normal position. The parts guide and hold movement, but they are not meant to be an unbreakable lock.
Grounding Statement
Picture a small control part being gently held by magnetic force while a spring tries to bring it back toward center.
Intuition Check
Do not read brake as the wheel brake used to stop the airplane. Here, brake means a device that holds or resists motion inside the control system.
Example Sentence 1
The magnetic brake/spring device in the autopilot servo allows the pilot to override the system simply by applying firm pressure to the yoke.
Example Sentence 2
When the pilot pressed the autopilot disconnect button, the magnetic brake released and the spring returned the yoke to its neutral position.