Definition
The condition in which two mechanical components are coupled together so that motion or force is transmitted from one to the other. A gear is engaged when its teeth are meshed with another gear; a clutch is engaged when its driving and driven members are locked together so power flows through them.
Plain English
Two parts are connected and working together, so when one moves, the other moves with it.
Context Anchor
Used in cockpit procedures and maintenance descriptions, such as an autopilot being engaged, a brake being engaged, or a locking device being engaged.
Derivation
From the French 'engager,' meaning to bind or pledge. The mechanical sense carries the same idea: two parts are bound to one another so they act as one.
Why Pilots Care
Knowing whether a component is engaged or disengaged matters operationally: a starter must disengage after the engine starts, an autopilot must be confirmed engaged before it will hold a heading or altitude, and a propeller governor's pitch-change mechanism must be properly engaged for the prop to respond.
Intuition Check
Do not read engaged here as “busy” or “involved.” In aviation use, it usually means connected, locked, or active.
Example Sentence 1
After the engine started, the pilot released the starter switch and the starter gear disengaged from the flywheel.
Example Sentence 2
Confirm the starter is disengaged before advancing the throttle.