Definition
An electrical switch that changes state when a target object comes near it, without any physical contact between the switch and the target. Proximity switches sense the presence or absence of a metal object through changes in a magnetic or electromagnetic field, and are commonly used to detect the position of landing gear, doors, and flight control surfaces.
Plain English
A switch that turns on or off when something gets close to it, instead of needing to be pressed or touched.
Context Anchor
Seen in aircraft maintenance and systems discussions, especially with landing gear position, gear doors, flight control positions, and other parts that must be sensed as open, closed, extended, or retracted.
Derivation
Proximity comes from the Latin proximus, meaning nearest. The name describes exactly how the switch works: it reacts to nearness rather than to touch.
Why Pilots Care
Provides reliable indication of critical component positions such as gear down-and-locked or control surface travel limits.
Analogy
It is like an automatic door sensor at a store: the door system reacts because something is close, not because you pushed a button.
Intuition Check
Do not assume a proximity switch must be physically pressed like a light switch. In this use, the key idea is that it senses a nearby target and changes the signal when the target is close enough.
Example Sentence 1
When the nose gear extended and locked, the proximity switch closed and the green gear-down light came on.
Example Sentence 2
During the preflight check the pilot verified that the flap proximity switches were operating correctly.