Definition
An instrument that measures the angle of inclination, slope, or tilt relative to the horizontal or vertical. In aircraft instruments, the clinometer is the curved glass tube containing a ball in fluid found at the bottom of the turn-and-slip indicator or turn coordinator; the ball's position shows whether the aircraft is in coordinated flight, slipping, or skidding.
Plain English
A small tool that shows tilt or angle. In the cockpit, it is the little ball-in-a-tube on the turn indicator that tells the pilot whether the turn is balanced or whether the aircraft is sliding sideways through the air.
Context Anchor
Seen in aircraft maintenance, rigging, and inspection procedures where a part must be set or checked at a specific angle.
Derivation
From the Greek 'klinein' meaning 'to lean or slope,' combined with '-meter' meaning 'measure.' So a clinometer literally means 'a leaning-measurer' — a device that measures how something is tilted.
Why Pilots Care
Allows the pilot to detect and correct slips or skids that reduce control effectiveness and increase stall risk in turns.
Analogy
A clinometer is like a protractor combined with a level. Instead of only showing whether something is level, it shows the amount of tilt.
Intuition Check
A clinometer is not an aircraft control instrument for flying the airplane. It is a measuring tool used to check the angle of a surface or component.
Example Sentence 1
During the climbing turn, the instructor reminded the student to add right rudder until the ball in the clinometer was centered.
Example Sentence 2
A skid was evident when the clinometer ball moved toward the outside of the turn.