Definition
Small electrical switches that open or close a circuit when a mechanical part moves into or out of a specific position. In aircraft, they are commonly used to sense the position of components such as landing gear, flaps, doors, and squat (weight-on-wheels) systems, and to trigger warning lights, horns, or interlocks based on that position.
Plain English
Tiny switches that turn a circuit on or off when something physically pushes against them. The aircraft uses them to know whether a part — like the landing gear or a door — is actually where it should be.
Context Anchor
Seen during preflight inspections of aircraft systems that use position indications, warning lights, or safety interlocks.
Derivation
‘Micro’ comes from the Greek mikros, meaning ‘small.’ The name refers to the very small physical movement needed to flip the switch — often a fraction of a millimetre — not to the size of the switch itself.
Why Pilots Care
They provide reliable position feedback for critical systems, helping confirm landing gear is down and locked or flaps are at the commanded setting before takeoff or landing.
Analogy
Like the small button inside a fridge door that turns the light on when you open it — a tiny movement of the door triggers the switch.
Intuition Check
Do not read “micro” as meaning computer-based or electronic in the modern digital sense. A micro switch is usually a small physical switch moved by contact with a part.
Example Sentence 1
During preflight, the pilot checked that the squat switch — a micro switch on the main gear — was clean and free of debris.
Example Sentence 2
The pilot extended the flaps and watched the indicators confirm that the micro switches had detected the new position.