Definition
A mechanical or electrical device that prevents a system or component from operating unless certain conditions are met, or that prevents two related actions from occurring simultaneously when doing so would be unsafe or damaging.
Plain English
A safety feature built into a system that blocks something from happening unless it is safe to happen. It locks one action to another so the wrong sequence cannot occur.
Context Anchor
Seen in aircraft system descriptions, cockpit controls, and maintenance procedures where one action is allowed or blocked based on another condition.
Derivation
From 'inter-' (between) and 'lock.' The name describes the function: two things are locked to each other so that the state of one controls whether the other can operate.
Why Pilots Care
Interlocks prevent costly or dangerous mistakes — like raising the landing gear while the aircraft is on the ground, or starting an engine with the propeller controls in the wrong position. If an interlock fails or is bypassed, the protection it provided is gone.
Intuition Check
Interlock does not simply mean two parts are connected. In aviation use, it usually means the connection controls whether an action is allowed to happen.
Example Sentence 1
The squat switch acts as an interlock that prevents the landing gear from being retracted while the aircraft's weight is on the wheels.
Example Sentence 2
Door interlocks keep the pressurization system from activating until every exit is fully closed and latched.